Ceylon cinnamon (Cinnamomum verum). The inner bark is the part used.

Herbs & Botanicals · Herbs · Bark spice with mixed, low-certainty evidence for blood sugar; cassia carries a coumarin liver caution

Cinnamon

Q: Does cinnamon lower blood sugar or help with diabetes?

Maybe a little, but the research disagrees. Several pooled analyses of small trials in type 2 diabetes find fasting blood sugar lower by roughly 10 to 25 mg/dL and HbA1c lower by 0.1 to 0.6 points. The Cochrane review (2012) called the evidence insufficient, and a 2022 analysis of studies it called very poor quality found no difference in HbA1c. We rate HbA1c as mixed and fasting sugar as low. Cinnamon is not a replacement for diabetes treatment.

Q: What is the difference between Ceylon and cassia cinnamon?

They are different species. Ceylon cinnamon (Cinnamomum verum, also called true cinnamon) is low in coumarin. Cassia (Cinnamomum aromaticum, usually written C. cassia) is the cheaper, more common kind and contains far more coumarin. Most studies on blood sugar used cassia or did not name the species. Labels often just say cinnamon; look for Cinnamomum verum or zeylanicum on the label.

Q: Can cinnamon harm the liver?

Cassia can, in sensitive people, because of its coumarin. LiverTox reports isolated, rare cases of liver injury with cinnamon, and we found two published case reports (both recovered after stopping). Short trials, including a 12-week cassia trial and a meta-analysis of seven trials, saw no rise in liver enzymes overall. That does not rule out rare reactions. People with liver disease should avoid cassia supplements.

Q: Is it safe to take cinnamon with diabetes medicines?

Cinnamon lowers blood sugar a little, so in theory it could add to insulin or tablets and cause low blood sugar. The trials that added cinnamon to usual diabetes drugs did not report severe lows in their abstracts, but they were small. Tell your doctor or pharmacist before starting a cinnamon supplement.

Q: Does cinnamon lower cholesterol or blood pressure?

Slightly in some analyses, not in others. Reviews in people with type 2 diabetes find lower triglycerides and total cholesterol; an umbrella analysis found changes of about 1 mg/dL. For blood pressure, one review found a 5 mmHg fall in the top number and another found almost none. A Ceylon trial designed to lower LDL cholesterol found no significant drop. We rate these low or mixed.

Q: Does cinnamon help with weight loss?

Barely. Pooled trials show an average loss under 1 kg, and one small trial found a cinnamon drink slightly reduced fullness. One woman developed liver injury after taking cinnamon for weight loss over a long time (a single case report).

Q: Does cinnamon help polycystic ovary syndrome (PCOS)?

Possibly for insulin resistance. Pooled small trials find lower fasting sugar and insulin resistance, but the trials are few and one pilot found no change in insulin resistance, lipids or androgens. For hormones and ovaries the evidence is insufficient. Trials of combination products cannot be credited to cinnamon.

Q: Is cinnamon safe in pregnancy or while breastfeeding?

In food amounts, NCCIH says both cassia and Ceylon appear safe in pregnancy, but it considers larger amounts of Ceylon unsafe in pregnancy. For breastfeeding, LactMed says no data exist on the safety of cinnamon for nursing mothers or babies. In rats, a large extract dose given to nursing mothers affected the grown offspring. Stay with food amounts and ask your clinician about supplements.

Q: Is cinnamon safe for children, and what is the cinnamon challenge?

Children reach the coumarin limit sooner because they weigh less, so regular use of cassia is the concern. The 'cinnamon challenge' means swallowing a spoonful of dry powder as a dare. NCCIH warns it can cause serious harm; ground cinnamon fibres can stay in the lungs and cause lasting inflammation.

Q: Can cinnamon cause mouth sores or allergy?

Yes, in some people. Cinnamon flavouring (cinnamaldehyde) in gum, sweets, toothpaste or mouthwash can cause mouth inflammation. In a series of 74 patients the lesions cleared within a week of stopping the product. Undiluted cinnamon oil can also irritate or burn skin and mouth.

Cinnamomum verum J.Presl (Ceylon cinnamon); Cinnamomum aromaticum Nees, usually called C. cassia (cassia) · also called Cinnamon, Ceylon cinnamon, true cinnamon, cassia, Chinese cinnamon, canela (Spanish)

Cinnamon is the dried inner bark of trees in the laurel family. Ceylon cinnamon (Cinnamomum verum) has little coumarin; cassia (Cinnamomum aromaticum, usually called C. cassia) is the common cheaper kind with much more coumarin, which can harm the liver in sensitive people. It is a kitchen spice and is also sold as capsules, extracts and oil.

General information, not medical advice. Last substantive update October 25, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

About Cinnamon

Cinnamon is the dried inner bark of trees in the Cinnamomum genus. Two species matter for health and are very different: Ceylon cinnamon (Cinnamomum verum, 'true cinnamon') has little coumarin; cassia (Cinnamomum aromaticum, usually called C. cassia) is the common cheaper kind and has much more coumarin, which can harm the liver in sensitive people. The best-studied use is blood sugar in type 2 diabetes, where the research is mixed and rated low to mixed. Other uses (cholesterol, blood pressure, PCOS, weight) are rated low or mixed, and there is no human research on memory.

What it is

Cinnamon is the dried inner bark of evergreen trees of the laurel family (Lauraceae). Ceylon cinnamon is Cinnamomum verum J.Presl, once called Cinnamomum zeylanicum. Cassia is a separate species, listed in the GBIF plant database as Cinnamomum aromaticum Nees and widely written Cinnamomum cassia. This page keeps the two apart wherever the research does.

Shops often just say 'cinnamon'. In an Italian survey of 34 samples about half were cassia, one in ten a blend and under four in ten Ceylon. NCCIH also notes that products often do not state the type.

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Traditional and current uses

Cinnamon has been used in traditional Indian and Chinese medicine for digestive complaints, headache, fever and missing periods, and more recently for diabetes, cholesterol and blood pressure. The EU accepts traditional use of cinnamon bark and bark oil for mild stomach and bowel cramps, bloating and wind (we could only read search-result text of that monograph).

Today people mainly take cinnamon for blood sugar, cholesterol and weight. Most of those uses are studied in small, short trials.

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What is in it and how it works

The flavour comes mainly from cinnamaldehyde. Cassia is rich in coumarin. Ceylon has the lowest coumarin of the four species compared in one study, and the most eugenol. Polyphenols such as procyanidin A2 are also present.

In the lab and in animals, cinnamon compounds slow starch digestion, help cells take up glucose, damp inflammation and damage bacterial cell walls. One Ceylon extract blocked a starch-digesting enzyme in a test tube and lowered glucose in the first hour after a meal in healthy volunteers. Most of the mechanism work is not shown in people, and no human data on how well cinnamon compounds reach the blood were found.

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What the research shows

Many small trials, pooled in many reviews, give mixed answers on blood sugar. Some pooled results show fasting blood sugar lower by about 10 to 25 mg/dL and HbA1c by 0.1 to 0.6 points; others, including the Cochrane review (2012) and a 2022 analysis judged to be of very poor-quality studies, find no clear effect. Trials are short (usually under four months), use unnamed or mixed cinnamon types and show very high disagreement between trials.

Cholesterol, blood pressure, weight, inflammation and PCOS results are small and not consistent. No trial has tested heart attacks, strokes, kidney disease or deaths. Ceylon cinnamon, the lower-coumarin kind, has few trials, and the two 2025 trials have commercial links. No human trial of cinnamon for memory or Alzheimer disease was found.

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At a glance

Traditional uses history, not proof

Traditional Indian and Chinese medicine: digestive complaints, headache, fever and missing periods (LiverTox, a review).
European traditional use: mild stomach and bowel cramps, bloating and wind (EMA monograph; search-result text only).
Chinese Pharmacopoeia wording: dispersing cold and relieving pain (as quoted in a lab paper).

Studied for research

Blood sugar (HbA1c, fasting glucose, insulin resistance) in type 2 diabetes, mixed to low
Cholesterol, blood pressure, weight, inflammation, PCOS, low or mixed
Painful periods, diarrhoea and indigestion, mouth germs, very low
Memory and Alzheimer disease, insufficient (no human trials)

Main compounds

Cinnamaldehyde, the main flavour compound
Coumarin, much higher in cassia than in Ceylon cinnamon
Eugenol and cinnamic acid
Polyphenols such as procyanidin A2

Common forms

Bark sticks (quills) and ground powder as a spice
Capsules or powder supplements
Water or alcohol extracts
Cinnamon oil (not for undiluted use)
Tea

Research links: US National Center for Complementary and Integrative Health: Cinnamon · German Federal Institute for Risk Assessment (BfR): coumarin in cinnamon · LiverTox: Cinnamon (PubMed record) · LactMed: Cinnamon (PubMed record) · GBIF: Cinnamomum verum · GBIF: Cinnamomum aromaticum · Research Library · Genes & Biomarkers Library

The plant and its history

Accepted scientific name: Cinnamomum verum J.Presl (Ceylon cinnamon, true cinnamon). Cassia is a separate species: Cinnamomum aromaticum Nees in the GBIF backbone, commonly written Cinnamomum cassia (L.) J.Presl or C. cassia Blume.
Naming authority: C. verum: J.Presl, in Rostl. 2: 36 (1825), accepted species in GBIF (usageKey 3033987, confidence 99, family Lauraceae, order Laurales). C. aromaticum: Nees, in Pl. Asiat. Rar. 2: 74 (1831), accepted in GBIF (usageKey 3033982, confidence 97). In NCBI Taxonomy the cassia name (taxid 230708) is filed as Neolitsea cassia, which shows the cassia name is unsettled across databases. This page keeps the two cinnamons apart.
Synonyms: Cinnamomum zeylanicum Blume (synonym of C. verum, GBIF 3033988; the name used in older papers); Cinnamomum cinnamomum (L.) H.Karst.; Camphorina cinnamomum (L.) Farw.; Cinnamomum aromaticum J.Graham; Cinnamomum aromaticum var. longifolium Lukman. (listed under C. aromaticum, not C. verum); Laurus cinnamomum Andrews (listed under C. aromaticum); Laurus malabathrum Wall. ex Nees (listed under C. aromaticum)
Common names: Ceylon cinnamon (English); True cinnamon (English); Cassia (English (the other species, C. aromaticum / C. cassia)); Chinese cinnamon (English (usually cassia)); Canela de Ceilan (Spanish (Ceylon cinnamon)); Canela de la China (Spanish (cassia)); Batavia cinnamon / Indonesian cassia (English (Cinnamomum burmanni, NCBI taxid 119261)); Saigon cinnamon (English (Cinnamomum loureiroi))
Botanical family: Lauraceae, the laurel family (order Laurales), which also holds bay laurel, avocado and camphor trees. The class label 'magnoliids' is general knowledge and not checked.
Classification: Plantae > Tracheophyta > Magnoliopsida (magnoliids) > Laurales > Lauraceae > Cinnamomum > Cinnamomum verum (Ceylon) and Cinnamomum aromaticum / cassia (cassia)
Native range: Ceylon cinnamon is native to Sri Lanka and parts of South Asia (LiverTox, NCCIH: grows mainly in Sri Lanka). Cassia is grown mainly in China and South-East Asia (general knowledge; not verified here). NCCIH notes cassia is the most common type sold in North America.
Habitat: Tropical evergreen trees grown on plantations. Not verified from a flora; general knowledge only.
What the plant looks like: Roots: Not covered.; Stems: The bark is the part used. Not verified from a flora.; Leaves: Evergreen, leathery leaves. General description, not checked.; Flowers: Small flower clusters. General description, not checked.; Fruit: Small dark berries. General description, not checked.
Cultivation: Grown commercially for the inner bark. Details were not researched.
Harvest and processing: The inner bark is stripped, dried and sold as rolled quills or ground powder. General knowledge, not verified from a source read. A 2023 study found that species can be told apart by chemical profile (Rana and Sheu), not by powder appearance.
Look-alikes and adulterants: Name: Cassia (Cinnamomum aromaticum / C. cassia); Note: The most important look-alike. Much higher coumarin (BfR: about 3,000 mg/kg average). Often sold simply as 'cinnamon'. In an Italian survey about half of cinnamon samples were cassia.; Name: Indonesian cassia (Cinnamomum burmanni); Note: Accepted species in GBIF (key 3033985); counted among the cheaper, hepatotoxic substitutes in Rana and Sheu 2023. Used in the cinnamon tea trial and in the DLBS3233 combination.; Name: Saigon cinnamon (Cinnamomum loureiroi); Note: Accepted species in GBIF (key 4182513); listed with the cheaper substitutes in Rana and Sheu 2023.; Name: Camphor tree (Cinnamomum camphora); Note: A different Cinnamomum species used for camphor products; not a cinnamon spice. Not researched further.
Sustainability and conservation: Not assessed here.

The plant and the parts used

Ceylon cinnamon (Cinnamomum verum) bark, close-up — Ceylon cinnamon (Cinnamomum verum) bark.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
Traditional Indian, Chinese and other herbal medicine (as summarised by LiverTox)	LiverTox says cinnamon has been used in traditional Indian and Chinese medicine for digestive symptoms, headache, fever and absence of periods, and more recently for diabetes, high cholesterol and high blood pressure.	p42551031
Chinese medicine (as summarised by trial authors)	Heydarpour 2020 lists headache, toothache, common cold, diarrhoea, flatulence, fever and absence of periods as traditional uses. Lu 2012 says cinnamon has been used as a traditional treatment in China for thousands of years (the authors' statement; not independently checked). The cassia study of Li 2021 cites the Chinese Pharmacopoeia 2015 for dispersing cold, relieving pain, warming the channels and promoting blood circulation.	p32151755
Traditional digestive use in Europe (EMA/HMPC)	The EU monograph on Cinnamomum verum bark and bark oil (compiled 2011) accepts traditional use for mild spasmodic stomach and bowel complaints including bloating and wind. Only search-result text was read.	s-ema-hmpc-cinnamon-oil
Modern trade	Cassia has largely replaced Ceylon cinnamon in the European food market because it is cheaper (Lungarini 2009).	p19680836

Traditional use shows how a plant was used. It does not show that a supplement works or is safe today.

What is inside, and how it may work

What the plant contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.

Main compounds

Compound	Family	Where it is concentrated	Activity studied	Level of evidence
Cinnamaldehyde PubChem 637511	phenylpropanoid aldehyde	Bark (both species); bark oil The EMA draft report is said to describe bark with up to 4% essential oil, mainly cinnamaldehyde (60 to 75%) (search-result text; not verified).	Gives cinnamon its flavour and is the main compound tested in the lab. Animal studies show glucose and fat lowering through several pathways; it is changed in the body to cinnamyl alcohol, methyl cinnamate and cinnamic acid; it can sensitise the mouth and skin in some people. ^{74 61 29 79}	Animal research
Coumarin PubChem 323	benzopyrone (lactone)	Bark; far higher in cassia Cassia about 3,000 mg/kg on average, highest measured 10,000 mg/kg; Ceylon low (BfR). Ceylon had the lowest coumarin of four species in a GC-MS comparison (1.90% of the profile) (Rana 2023). In 1 g of cinnamon-bark decoction the Japanese study found 3.0 mg coumarin.	Liver-toxic in a sensitive subgroup of people (as a drug); EFSA and BfR TDI 0.1 mg/kg body weight a day; European limits on cinnamon foods. ^{78 1 24 53}	Human data
Eugenol PubChem 3314	phenylpropanoid (phenol)	Bark; present at 5.77% of the profile in Ceylon in one comparison 5.77% of the GC-MS profile in C. verum, the highest of four species (Rana 2023). LactMed lists eugenol among the compounds.	Aromatic and antimicrobial compound in lab studies; its role in human effects has not been shown. ^{53 47}	Laboratory research
Cinnamic acid PubChem 444539	phenylpropanoid acid	Bark; also a body metabolite of cinnamaldehyde Not found in the abstracts read.	Antibacterial in lab studies; a metabolite of cinnamaldehyde. ^{61 74}	Laboratory research
Procyanidin A2 and related polyphenols PubChem 124025	A-type proanthocyanidins (polyphenols)	Bark Not found in the abstracts read.	Cinnamon polyphenols are described as antioxidant and as inhibiting tau aggregation in lab models (Momtaz 2018). A specific compound's role in human effects is not shown. ⁴¹	Laboratory research
Cinnamyl alcohol PubChem 5315892	phenylpropanoid alcohol	Bark; also a metabolite of cinnamaldehyde Not found in the abstracts read.	Named as a metabolite of cinnamaldehyde (Zhu 2017). ⁷⁴	Animal research

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
Starch-digesting enzyme (alpha-amylase) inhibition	Pancreatic alpha-amylase	A Ceylon cinnamon hydro-alcoholic extract blocked pancreatic alpha-amylase in a test tube (IC50 25 micrograms/mL) and lowered the blood sugar response to starch in rats from 12.5 mg/kg. In 18 healthy volunteers 1 g lowered glucose over the first hour by 21.2% (p<0.05), without raising insulin. ⁵	Human data
Glucose uptake and insulin signalling (several pathways)	GLUT4; PI3K/IRS-1; AMPK; PPARs; RBP4; ERK/JNK/p38 MAPK	Reviews of mainly test-tube and animal work say Ceylon cinnamon and cinnamaldehyde increase cellular glucose uptake (GLUT4 movement to the membrane), glycogen making in the liver, and insulin signalling, and reduce glucose making in the liver and enzyme PTP1B, in diabetic animals. ^{54 74}	Animal research
Slowed stomach emptying and appetite hormone signalling	TRPA1; ghrelin	Cinnamaldehyde is reported to slow stomach emptying and act through a TRPA1-ghrelin pathway in animals. In 21 healthy adults a 2 g cinnamon infusion did not change energy use but reduced fullness. ^{74 57}	Animal research
Brown fat heat production	Brown adipose tissue; mitochondrial uncoupling	Cassia extract raised body temperature and energy use in animals in cold and uncoupled mitochondria in brown fat cells. ³⁴	Animal research
Antioxidant and anti-inflammatory signalling	Nrf2; NF-kB	Cinnamaldehyde acts through the Nrf2 pathway in lab models (Zhu 2017). A trial in 44 people with type 2 diabetes found lower NF-kB (p 0.02) but no change in CRP, IL-6 or TNF-alpha. ^{74 10}	Human data
Bacterial cell damage	Bacterial membranes, ATPases, biofilms, quorum sensing	Cinnamon oils and compounds inhibit bacteria by damaging membranes, altering lipids, blocking ATPases, cell division and motility, and disrupting biofilms. Lab results only. ^{61 14}	Laboratory research
Tau and amyloid-beta clumping	Tau protein; amyloid-beta	Cinnamon extract blocked tau clumping and amyloid-beta aggregation in test-tube and animal models, according to a review. ⁴¹	Laboratory research
Coumarin liver toxicity	Not established	The reason some people are far more sensitive to coumarin's liver toxicity than animals is not known (Abraham 2010). ¹	Human data

Absorption, metabolism and elimination

Absorption: No human absorption data for cinnamon compounds were found in the abstracts read.
Distribution: Not found.
Metabolism: Cinnamaldehyde is turned into cinnamyl alcohol, methyl cinnamate and cinnamic acid in the body, per a review of animal work (Zhu 2017). A sensitive subgroup of humans is more susceptible to coumarin's liver effects than animals; the cause is unknown (Abraham 2010).
Elimination: Not found.
Bioavailability: Not found. Human blood-level studies of cinnamon bark compounds were not found in this search, so claims about how much reaches the blood cannot be made.

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Isolated compounds versus whole extracts

Cinnamon is a mixture. Cassia and Ceylon differ in coumarin (much higher in cassia) and probably in other compounds, and trials use powder, water extracts, alcohol extracts or oil. Results from one cannot be moved to another. Cinnamaldehyde alone is mainly tested in animals, and the one human trial that mixed cinnamon with another compound (berberine) cannot be credited to cinnamon. Water extracts of cassia contain less of the oil-soluble compounds; the BfR suggests water extracts as one way to cut coumarin, but the 2012 Wickenberg paper warns the benefit seen with cassia could be lost on replacing it.

Nutritional composition

USDA FoodData Central was not consulted for this page. Cinnamon is used in very small amounts, so its contribution of calories or vitamins is negligible (general knowledge; not verified here). Cinnamon is not a significant source of any nutrient at spice quantities.

19benefits and uses looked at

83studies and sources checked

Low certaintybest evidence rating found

14lab markers tracked in trials

4 mixed findings10 low certainty3 very low certainty2 not enough evidence

What was looked at

The 19 benefits and uses checked for Cinnamon, each with how strong the evidence is. Tap one to open it.

Long-term blood sugar (HbA1c) in type 2 diabetesMixed findings
Fasting blood sugar in type 2 diabetesLow certainty
Insulin resistance (HOMA-IR) and fasting insulinLow certainty
Blood sugar after a meal or glucose drink (single doses)Mixed findings
Prediabetes and impaired glucose toleranceLow certainty
Ceylon cinnamon (Cinnamomum verum) on blood sugar, on its ownLow certainty
Cassia cinnamon (Cinnamomum cassia / aromaticum) on blood sugarMixed findings
Metabolic syndromeLow certainty
Memory, thinking and Alzheimer diseaseNot enough evidence
Blood fats (cholesterol, triglycerides) in type 2 diabetesLow certainty
Blood fats in adults generally and in metabolic syndromeMixed findings
Blood pressureLow certainty
PCOS: blood sugar, insulin and body measuresLow certainty
PCOS: hormones and ovariesNot enough evidence
Body weight and waistLow certainty
Inflammation and oxidative stress markersLow certainty
Painful periods (primary dysmenorrhoea)Very low certainty
Digestion: diarrhoea, bloating and indigestionVery low certainty
Mouth health and germs (antimicrobial effects)Very low certainty

Lab markers tracked in the studies

HbA1c (three-month blood sugar average, %)Fasting blood glucoseHOMA-IR (insulin resistance estimate)Blood sugar after eating or a glucose drinkFasting insulinLDL cholesterol (mg/dL)HDL cholesterol (mg/dL)Triglycerides (mg/dL)Total cholesterol (mg/dL)Systolic blood pressure (top number, mmHg)Diastolic blood pressure (bottom number, mmHg)Body weight and BMIC-reactive protein (CRP, mg/L)Testosterone and other androgens (PCOS)

What is Cinnamon good for?

The main proposed uses and how strong the human evidence is for each. "Mixed" means studies disagree; "low" means small or weak studies point one way; "insufficient" means too little or no human evidence. Nothing here is rated moderate or high.

Long-term blood sugar (HbA1c) in type 2 diabetesMixed findingsHbA1c is the three-month blood sugar average. Some pooled analyses find a small drop with cinnamon and others find none. The size, where found, is small (roughly 0.1 to 0.6 points). Reviewers disagree, so the evidence is mixed. Reviewers disagree, so no firm conclusion is possible. Fasting blood sugar in type 2 diabetesLow certaintyMost pooled analyses find fasting blood sugar is lower with cinnamon, on average about 10 to 25 mg/dL. The studies are small, disagree a lot and are of uneven quality, so the certainty is low. Insulin resistanceLow certaintyPooled analyses suggest cinnamon may lower a lab estimate of insulin resistance (HOMA-IR). A careful clamp study in people with impaired glucose tolerance found no change. Certainty is low. Blood sugar after a meal (single-dose tests)Mixed findingsSingle-dose tests give mixed results. Some find a lower peak after a sugar drink; others find nothing. This is a short-term effect and not proof of lasting benefit. Prediabetes and impaired glucose toleranceLow certaintyIn people with prediabetes the results conflict: a small 2024 crossover trial using continuous glucose monitors found lower glucose, while earlier small trials in impaired glucose tolerance found no benefit. Ceylon cinnamon and cassia compared for blood sugarLow certaintyCeylon cinnamon (true cinnamon) has far fewer human trials than cassia. Two recent Sri Lankan trials point to a small glucose benefit, one is industry-linked, and an older small trial found nothing. It is not yet clear Ceylon works as well as cassia. Most older diabetes trials used cassia or an unnamed bark. They give mixed results. Cassia is also the type with high coumarin, so the benefit has to be weighed against liver risk. For cassia the small trials split: some found lower HbA1c and weight, others found nothing. Metabolic syndromeLow certaintyOne 16-week trial in India found many improvements with cinnamon in people with metabolic syndrome, larger than other trials usually report. It has not been confirmed by independent trials. Cholesterol and triglyceridesMixed findingsPooled trials in people with type 2 diabetes find lower triglycerides and total cholesterol, and sometimes LDL, with cinnamon. Effects are small and the trials disagree. Across all adults, pooled lipid results are small and mixed. Triglycerides and total cholesterol fall slightly in some reviews; LDL and HDL change little. Blood pressureLow certaintyPooled analyses suggest a small drop in blood pressure, mostly in people with diabetes or overweight. Reviews disagree on the size, and it is not shown to help people with diagnosed high blood pressure. Polycystic ovary syndrome (PCOS)Low certaintyIn women with polycystic ovary syndrome (PCOS), pooled small trials suggest lower fasting sugar and insulin resistance. Weight changes are small. Trials are few. For hormones (testosterone, AMH) and ovary size, evidence is thin and mixed. One pilot found a smaller ovary volume; another found no androgen change. For PCOS hormones and ovaries the evidence is insufficient. Body weight and waistLow certaintyPooled analyses find very small reductions in weight and BMI with cinnamon, under about 1 kg on average. This is too small to matter much on its own. Inflammation and oxidative stress markersLow certaintyPooled analyses find lower CRP (an inflammation marker) with cinnamon, but a careful trial in people with diabetes found no change. Evidence is low. Painful periodsVery low certaintyA small meta-analysis suggests cinnamon may ease period pain. A Cochrane review could not draw any conclusion about cinnamon. Digestion: diarrhoea, bloating, indigestionVery low certaintyOne trial of a cassia water extract found slower gut transit in people with diarrhoea. A Cochrane review found cinnamon oil made little or no difference to indigestion. Traditional use for gas and cramps is recognised in Europe. Mouth health and germsVery low certaintyIn test tubes cinnamon oil and extracts kill many germs. In people, one small trial found a cinnamon oil mouthwash helped oral thrush about as well as an antifungal drug. Cinnamon can also irritate the mouth (see Safety). Memory, thinking and Alzheimer diseaseNot enough evidenceWe found no human trial of cinnamon for memory or thinking. Lab and animal work suggests cinnamon compounds may affect brain proteins linked to Alzheimer disease, but this has not been tested in people.

Benefits, one by one

Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.

Long-term blood sugar (HbA1c) in type 2 diabetes

Mixed findings

HbA1c is the three-month blood sugar average. Some pooled analyses find a small drop with cinnamon and others find none. The size, where found, is small (roughly 0.1 to 0.6 points). Reviewers disagree, so the evidence is mixed.

14 studiesStudies used cinnamon bark powder or extract from about 120 mg to 6 g…

Studies, doses and limits

What the trials found

Pooled trials disagree. Akilen 2012 (6 trials, 435 people) found a tiny drop of 0.09 points. Allen 2013 (10 trials, 543 people) found no significant drop (-0.16%, CI -0.39 to 0.02). Namazi 2019 (18 trials) found -0.24% (CI -0.48 to -0.01). Deyno 2019 (16 trials) and Krittanawong 2022 (23 studies, very poor quality) found no change. Moridpour 2024 (24 trials) and de Moura 2025 (28 trials, 3,054 people) found drops; de Moura reported -0.56 with 94% heterogeneity. The 2012 Cochrane review found no significant HbA1c difference. An umbrella analysis of 11 meta-analyses found -0.10%. Single trials: Lira Neto 2022 (160 people, 3 g, on diabetes drugs) -0.2 points vs placebo; Talaei 2017 (44 people) no change; Lu 2012 (66 people on gliclazide) HbA1c fell in both extract groups; a 2025 Ceylon extract trial (210 people) reported HbA1c falling from baseline.

Results

Typical pooled drops are about 0.1 to 0.6 HbA1c points when a drop is found. For comparison, many diabetes drugs lower HbA1c by more than that.

Effect sizes as reported

Akilen -0.09 points; Allen -0.16% (not significant); Namazi -0.24%; umbrella -0.10%; de Moura -0.56 (CI -0.99 to -0.13, I2 94%); Moridpour SMD -0.67; Krittanawong 0.0 (CI -0.44 to 0.45); Lira Neto -0.2 vs placebo.

Why this rating

Pooled analyses split between small benefit and none. Heterogeneity is very high (I2 about 77 to 94 percent), trials are small, short (about 6 to 18 weeks), and cinnamon type, part and dose vary or are not stated. One often-cited trial (Khan 2003) has a journal Expression of Concern.

Form and dose studied

Studies used cinnamon bark powder or extract from about 120 mg to 6 g a day, most often cassia or an unnamed species; recent Sri Lankan trials used a Ceylon extract.

Who was studied

Adults with type 2 diabetes, often already on metformin or other diabetes drugs.

Limits

No trial lasted more than about 4 months. HbA1c changes are a lab marker, not proof of fewer complications. Some trials are industry-linked (see studies).

Why researchers looked

HbA1c is the number doctors use to judge diabetes control, so it is the most important blood sugar outcome.

Traditional use

Cinnamon bark has long been used as a spice and in traditional medicine in South Asia, China and elsewhere; the diabetes use is mainly modern.

Proposed mechanism Preliminary mechanism

Lab and animal work suggests compounds in cinnamon bark (cinnamaldehyde and tea-like polyphenols) may slow starch digestion, help cells take up glucose and make insulin work better. Ceylon extract blocked a starch-digesting enzyme in a test tube and lowered the sugar response to starch in rats. None of this shows the same thing happens at the doses people take.

A proposed mechanism does not show that the effect happens in people.

Cassia contains coumarin, which can harm the liver in sensitive people (see Safety). Cinnamon can add to the effect of diabetes medicines, so people on them should tell their prescriber and watch for low sugar.

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Fasting blood sugar in type 2 diabetes

Low certainty

Most pooled analyses find fasting blood sugar is lower with cinnamon, on average about 10 to 25 mg/dL. The studies are small, disagree a lot and are of uneven quality, so the certainty is low.

12 studiesMostly cassia or unnamed bark powder; doses 120 mg to 6 g a day for 4…

Studies, doses and limits

What the trials found

Davis 2011 (8 trials) found a drop of 0.49 mmol/L. Allen 2013 found -24.59 mg/dL. Namazi 2019 found -19.26 mg/dL (I2 96.5%). Deyno 2019 found -0.545 mmol/L. de Moura 2025 found -15.26 mg/dL. Moridpour 2024 found SMD -1.32. An umbrella analysis found -10.93 mg/dL. The Cochrane review (2012, 10 trials, 577 people, mostly cassia, mean 2 g a day) called the fasting-glucose effect inconclusive and the evidence insufficient; it searched only to January 2012. In single trials Lira Neto 2022 found -0.55 mmol/L vs placebo; Talaei 2017 found no change. The 2025 Ceylon extract trial in people with LDL 100 to 190 mg/dL found fasting glucose 8.59 mg/dL lower than placebo (secondary outcome; its main LDL result was null).

Results

Pooled drops of about 10 to 25 mg/dL. For comparison, a fasting reading of 126 mg/dL or more is the usual diabetes threshold.

Effect sizes as reported

Davis -0.49 mmol/L; Allen -24.59 mg/dL (CI -40.52 to -8.67); Namazi -19.26 mg/dL; de Moura -15.26 mg/dL (CI -22.23 to -8.30); umbrella -10.93 mg/dL; Cochrane inconclusive.

Why this rating

Direction is fairly consistent across pooled analyses, but heterogeneity is extreme (I2 83 to 96 percent), the Cochrane review found it inconclusive, trials are small and often at high or unclear risk of bias, and a more recent very-poor-quality analysis (Krittanawong) found no HbA1c effect.

Form and dose studied

Mostly cassia or unnamed bark powder; doses 120 mg to 6 g a day for 4 to 18 weeks.

Who was studied

Adults with type 2 diabetes or prediabetes.

Limits

Different products, species and doses; short trials; positive publication bias is possible; the 2003 Khan trial has an Expression of Concern.

Why researchers looked

Cinnamon has been tried as an add-on to help control fasting glucose.

Traditional use

Cinnamon bark has long been used as a spice and in traditional medicine in South Asia, China and elsewhere; the diabetes use is mainly modern.

Proposed mechanism Preliminary mechanism

A proposed mechanism does not show that the effect happens in people.

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Insulin resistance (HOMA-IR) and fasting insulin

Low certainty

Pooled analyses suggest cinnamon may lower a lab estimate of insulin resistance (HOMA-IR). A careful clamp study in people with impaired glucose tolerance found no change. Certainty is low.

6 studiesCinnamon capsules or powder; cassia in the clamp study.

Studies, doses and limits

What the trials found

Deyno 2019 found HOMA-IR lower by 0.714 (CI -1.388 to -0.04). de Moura 2025 found -0.76 (CI -1.13 to -0.39), with less heterogeneity (I2 22%). Moridpour 2024 found fasting insulin not significantly changed (SMD -0.17, CI -0.34 to 0.01). The umbrella analysis found insulin -2.01 IU/mL and HOMA-IR -0.61. In contrast, Wickenberg 2014 (21 people with impaired glucose tolerance, 12 g cassia a day for 12 weeks) used the gold-standard clamp test and found no change in insulin sensitivity. Gutierrez 2016 (10 obese women, 5 g cassia once) found no change in insulin sensitivity.

Results

HOMA-IR falls of roughly 0.6 to 0.8 units in pooled results.

Effect sizes as reported

Deyno -0.714; de Moura -0.76; umbrella -0.61; clamp trial: no significant change.

Why this rating

HOMA-IR is a calculation from fasting numbers, not a direct measure. The only direct (clamp) test was null in a very small study.

Form and dose studied

Cinnamon capsules or powder; cassia in the clamp study.

Who was studied

Adults with type 2 diabetes or prediabetes.

Limits

Surrogate marker; small trials; high heterogeneity.

Why researchers looked

Insulin resistance is the core problem behind type 2 diabetes and prediabetes.

Traditional use

Cinnamon bark has long been used as a spice and in traditional medicine in South Asia, China and elsewhere; the diabetes use is mainly modern.

Proposed mechanism Preliminary mechanism

A proposed mechanism does not show that the effect happens in people.

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Blood sugar after a meal or glucose drink (single doses)

Mixed findings

Single-dose tests give mixed results. Some find a lower peak after a sugar drink; others find nothing. This is a short-term effect and not proof of lasting benefit.

6 studiesSingle doses of 1 to 6 g (powder, extract, tea).

Studies, doses and limits

What the trials found

Ceylon extract (1 g) in 18 healthy volunteers lowered glucose over the first 60 minutes by 21.2% (p<0.05) but the 2-hour change (-14.8%) was not significant. Cassia (5 g) in 10 obese women lowered the 30-minute peak (140 vs 156 mg/dL) with no change in overall glucose curve. Ceylon cinnamon capsules (6 g) in 10 people with impaired glucose tolerance had no effect on glucose or insulin. Water extract in 36 people with type 2 diabetes had no effect. Cinnamon tea (C. burmannii) in non-diabetic adults slightly lowered the peak. de Moura 2025 pooled after-meal glucose in trials in people with type 2 diabetes: -39.22 mg/dL (CI -63.90 to -14.55; I2 100%).

Results

Results range from no effect to a 20 percent lower glucose in the first hour.

Effect sizes as reported

Beejmohun AUC 0-60 -21.2% (p<0.05), 0-120 -14.8% (p 0.15); Gutierrez peak 140 vs 156 mg/dL; Wickenberg 2012 no effect; Rachid 2022 no effect; de Moura -39.22 mg/dL.

Why this rating

Small crossover tests (10 to 36 people) of different cinnamons, extracts and doses disagree, and the pooled after-meal result has complete heterogeneity (I2 100%).

Form and dose studied

Single doses of 1 to 6 g (powder, extract, tea).

Who was studied

Healthy adults, people with impaired glucose tolerance, obesity or type 2 diabetes.

Limits

Tiny studies, one dose, several without placebo drinks.

Why researchers looked

Researchers tested whether cinnamon blunts the sugar spike after eating.

Traditional use

Cinnamon bark has long been used as a spice and in traditional medicine in South Asia, China and elsewhere; the diabetes use is mainly modern.

Proposed mechanism Preliminary mechanism

A proposed mechanism does not show that the effect happens in people.

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Prediabetes and impaired glucose tolerance

Low certainty

In people with prediabetes the results conflict: a small 2024 crossover trial using continuous glucose monitors found lower glucose, while earlier small trials in impaired glucose tolerance found no benefit.

3 studiesCinnamon spice 4 g a day (Zelicha, species not stated); cassia 12 g a…

Studies, doses and limits

What the trials found

Zelicha 2024: 18 adults with obesity and prediabetes took 4 g cinnamon spice or placebo for 4 weeks each (crossover); 24-hour glucose was lower on cinnamon (p<0.001), glucose peaks were lower (rise 9.56 vs 11.73 mg/dL, p 0.027) and triglycerides were lower. Wickenberg 2014 (cassia, 12 g a day, 12 weeks, 21 people with impaired glucose tolerance) and Wickenberg 2012 (Ceylon, single 6 g dose) found no benefit. No trial tested whether cinnamon prevents diabetes from developing.

Results

Zelicha: peak rise lower by about 2 mg/dL on average; other trials null.

Effect sizes as reported

Zelicha 24-hour glucose lower (p<0.001), peak 9.56 vs 11.73 mg/dL (p 0.027); Wickenberg: no significant changes.

Why this rating

Only three small trials, two null, one positive but with 18 people and no long-term outcome.

Form and dose studied

Cinnamon spice 4 g a day (Zelicha, species not stated); cassia 12 g a day (Wickenberg 2014); Ceylon 6 g single dose.

Who was studied

Adults with prediabetes or impaired glucose tolerance.

Limits

No trial on developing diabetes; short; small.

Why researchers looked

Prediabetes is where preventing diabetes might be possible, so cinnamon has been tested early.

Traditional use

Cinnamon bark has long been used as a spice and in traditional medicine in South Asia, China and elsewhere; the diabetes use is mainly modern.

Proposed mechanism Preliminary mechanism

A proposed mechanism does not show that the effect happens in people.

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Ceylon cinnamon (Cinnamomum verum) on blood sugar, on its own

Low certainty

Ceylon cinnamon (true cinnamon) has far fewer human trials than cassia. Two recent Sri Lankan trials point to a small glucose benefit, one is industry-linked, and an older small trial found nothing. It is not yet clear Ceylon works as well as cassia.

5 studiesStandardised Ceylon bark extracts at 250 mg to 1 g a day; Ceylon caps…

Studies, doses and limits

What the trials found

A 2012 review found no human studies of Ceylon cinnamon at that time (Ranasinghe 2012, only test-tube and animal work). Since then: the 2025 Ranasinghe trial (210 people with type 2 diabetes, standardised Ceylon extract 250 or 500 mg a day, 4 months) reported fasting glucose and HbA1c falling from baseline with better insulin resistance, but the abstract gives p values rather than group-difference numbers and all authors hold a patent. Muthukuda 2025 (150 adults, Ceylon extract 1 g a day, 12 weeks, funded by a spice company) missed its main LDL target but fasting glucose was 8.59 mg/dL lower than placebo, with a larger drop in people with type 2 diabetes. Wickenberg 2012 (10 people, single 6 g Ceylon dose) found no effect on after-meal glucose. Beejmohun 2014 (18 healthy volunteers, 1 g Ceylon extract) lowered glucose by 21.2% in the first hour.

Results

Numbers: fasting glucose 8.59 mg/dL lower than placebo (CI 0.59 to 16.59) in Muthukuda; others as above.

Effect sizes as reported

Muthukuda fasting glucose adjusted difference 8.59 mg/dL (CI 0.59 to 16.59); Ranasinghe 2025 p<0.05 vs baseline; Wickenberg 2012 null.

Why this rating

Two modern randomized trials lean positive but are industry-linked or patent-linked, report limited numbers, and one missed its primary goal. Older Ceylon work was in animals and test tubes.

Form and dose studied

Standardised Ceylon bark extracts at 250 mg to 1 g a day; Ceylon capsules 6 g single dose.

Who was studied

Adults with type 2 diabetes or raised cholesterol; healthy volunteers.

Limits

Few trials, commercial links, short follow-up. Results for cassia trials cannot be assumed for Ceylon.

Why researchers looked

Ceylon has little coumarin, so it is the safer choice for regular use, and people want to know if it works as well.

Traditional use

Ceylon cinnamon is native to Sri Lanka and is the 'true cinnamon' of the spice trade.

Proposed mechanism Preliminary mechanism

A proposed mechanism does not show that the effect happens in people.

Ceylon is much lower in coumarin than cassia (see Safety).

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Cassia cinnamon (Cinnamomum cassia / aromaticum) on blood sugar

Mixed findings

Most older diabetes trials used cassia or an unnamed bark. They give mixed results. Cassia is also the type with high coumarin, so the benefit has to be weighed against liver risk.

4 studiesCassia bark 3 to 12 g a day (powder capsules).

Studies, doses and limits

What the trials found

The Cochrane review (2012; mostly Cinnamomum cassia, mean 2 g a day) found the evidence insufficient. Wickenberg 2014 (21 people with impaired glucose tolerance; 12 g cassia a day for 12 weeks) found no change in insulin sensitivity, HbA1c, fasting glucose or liver enzymes (17 people finished). Delgadillo-Centeno 2023 (18 people with type 2 diabetes on metformin; 3 g cassia a day for 12 weeks) found lower weight (81.4 to 79.9 kg), BMI and HbA1c (53 to 45 mmol/mol) but no change in fasting glucose, blood pressure, lipids or arterial stiffness. Gutierrez 2016 (5 g cassia, once) lowered the 30-minute peak only.

Results

Mixed, very small trials.

Effect sizes as reported

Delgadillo HbA1c 53 to 45 mmol/mol (p 0.036); Wickenberg 2014 null; Cochrane insufficient.

Why this rating

Tiny trials (10 to 21 people) with opposite results; cassia chemistry also varies by source.

Form and dose studied

Cassia bark 3 to 12 g a day (powder capsules).

Who was studied

Adults with type 2 diabetes, impaired glucose tolerance or obesity.

Limits

Within-group testing in small trials; short.

Why researchers looked

Cassia is the cheap, common cinnamon in shops, and most glucose trials used it.

Traditional use

Cassia has been used in traditional Chinese medicine for centuries.

Proposed mechanism Preliminary mechanism

A proposed mechanism does not show that the effect happens in people.

High coumarin content in cassia: with these doses (3 to 12 g a day) coumarin intake would far exceed the European tolerable daily intake. See Safety.

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Metabolic syndrome

Low certainty

One 16-week trial in India found many improvements with cinnamon in people with metabolic syndrome, larger than other trials usually report. It has not been confirmed by independent trials.

2 studies3 g a day for 16 weeks (species not stated).

Studies, doses and limits

What the trials found

Gupta Jain 2017: 116 Asian Indians with metabolic syndrome took 3 g cinnamon or wheat flour for 16 weeks. The cinnamon group had greater falls in fasting glucose (0.3 mmol/L), HbA1c (2.6 mmol/mol), waist (4.8 cm) and BMI (1.3), and fewer still met the metabolic syndrome definition (34.5% vs 5.2%). A meta-analysis of cinnamon in metabolic syndrome and related disorders (Wu 2022; 12 studies, 773 people) found lower total cholesterol, triglycerides and LDL, but no significant lipid effect in European and American patients.

Results

Waist 4.8 cm and BMI 1.3 units lower than placebo in one trial.

Effect sizes as reported

Gupta Jain: fasting glucose difference 0.3 mmol/L (CI 0.2 to 0.5); HbA1c 2.6 mmol/mol (CI 0.4 to 4.9); metabolic syndrome 34.5% vs 5.2%.

Why this rating

One trial of moderate size, species not stated and registered after recruitment ended; results much larger than other trials.

Form and dose studied

3 g a day for 16 weeks (species not stated).

Who was studied

Asian Indian adults with metabolic syndrome.

Limits

Retrospective registration; single region; unnamed species.

Why researchers looked

Metabolic syndrome groups high sugar, belly fat, high blood pressure and abnormal blood fats.

Traditional use

Cinnamon bark has long been used as a spice and in traditional medicine in South Asia, China and elsewhere; the diabetes use is mainly modern.

Proposed mechanism Preliminary mechanism

A proposed mechanism does not show that the effect happens in people.

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Memory, thinking and Alzheimer disease

Not enough evidence

We found no human trial of cinnamon for memory or thinking. Lab and animal work suggests cinnamon compounds may affect brain proteins linked to Alzheimer disease, but this has not been tested in people.

1 studiesNot applicable.

Studies, doses and limits

What the trials found

No randomized human trial of cinnamon for cognition or dementia was found in our PubMed search. A 2018 review (Momtaz) says cinnamon extract blocks tau protein and amyloid-beta clumping in test-tube and animal models, and calls for human trials.

Results

No human data.

Why this rating

Only laboratory and animal work; no human evidence.

Limits

Everything is from models, not from people.

Why researchers looked

Because diabetes and Alzheimer disease are linked, researchers have looked at cinnamon compounds in the lab.

Traditional use

No well-documented traditional use for memory was found in the sources read.

Proposed mechanism Laboratory research

Cinnamon extracts reduced tau and amyloid-beta clumping and inflammation signals in test-tube and animal models, according to a review. These are early findings.

A proposed mechanism does not show that the effect happens in people.

Same as for other uses.

⁴¹

Blood fats (cholesterol, triglycerides) in type 2 diabetes

Low certainty

Pooled trials in people with type 2 diabetes find lower triglycerides and total cholesterol, and sometimes LDL, with cinnamon. Effects are small and the trials disagree.

7 studiesCinnamon capsules or powder, 120 mg to 6 g a day, 4 to 18 weeks.

Studies, doses and limits

What the trials found

Allen 2013 (10 trials) found triglycerides -29.59 mg/dL, total cholesterol -15.60, LDL -9.42 and HDL +1.66. Jamali 2020 (16 studies, 1,025 people) found triglycerides -26.27 mg/dL, total cholesterol -13.93, LDL -6.13 and no change in HDL. de Moura 2025 found lower total cholesterol, LDL and triglycerides in the capsule subgroup. Deyno 2019 found no significant lipid change. The 2025 Ceylon trial (500 mg group) reported lower total and LDL cholesterol. Muthukuda 2025, a Ceylon trial aimed at people with raised LDL, found no significant LDL drop (difference 6.05 mg/dL, CI -2.43 to 14.52). Zare 2019 found improved total, LDL and HDL cholesterol but not triglycerides.

Results

Triglycerides about 20 to 30 mg/dL lower and LDL about 6 to 9 mg/dL lower in pooled analyses.

Effect sizes as reported

Jamali: triglycerides -26.27 (CI -38.93 to -13.61), total cholesterol -13.93, LDL -6.13 (CI -10.72 to -1.53); Allen: triglycerides -29.59, LDL -9.42.

Why this rating

Pooled results are small and some reviews found nothing; heterogeneity is high; the one Ceylon trial built to test LDL was null.

Form and dose studied

Cinnamon capsules or powder, 120 mg to 6 g a day, 4 to 18 weeks.

Who was studied

Adults with type 2 diabetes.

Limits

Short trials; surrogate markers; mixed products.

Why researchers looked

Diabetes raises heart risk, so blood fats were measured in cinnamon diabetes trials.

Traditional use

Cinnamon bark has long been used as a spice and in traditional medicine in South Asia, China and elsewhere; the diabetes use is mainly modern.

Proposed mechanism Preliminary mechanism

Lab studies suggest cinnamon polyphenols may affect fat and cholesterol handling in the liver. This is early and not proven in people.

A proposed mechanism does not show that the effect happens in people.

Cassia contains coumarin, which can harm the liver in sensitive people (see Safety). Ceylon has little coumarin.

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Blood fats in adults generally and in metabolic syndrome

Mixed findings

Across all adults, pooled lipid results are small and mixed. Triglycerides and total cholesterol fall slightly in some reviews; LDL and HDL change little.

5 studiesCinnamon powder or extract, variable doses.

Studies, doses and limits

What the trials found

Maierean 2017 (13 trials, 750 people) found triglycerides -23.91 mg/dL and total cholesterol -13.92 mg/dL with no significant LDL or HDL change. Wu 2022 (12 studies, 773 people with metabolic syndrome) found total cholesterol -7.34, triglycerides -8.85 and LDL -6.18 mg/dL, but no significant effect in European and American patients. The umbrella analysis of 11 meta-analyses (Sarmadi 2023) found only about 1 mg/dL changes in total cholesterol and LDL and +0.47 mg/dL HDL, with no triglyceride effect. Krittanawong 2022 found no LDL or HDL change. Heydarpour 2020 pooled 5 trials in PCOS and found lower LDL, total cholesterol and triglycerides and higher HDL.

Results

Changes of about 1 to 24 mg/dL depending on the analysis.

Effect sizes as reported

Maierean: triglycerides -23.91 mg/dL (CI -34.54 to -12.40), LDL -6.19 mg/dL (not significant); Sarmadi: total cholesterol -1.01, LDL -0.82, HDL +0.47, triglycerides -0.13 (not significant).

Why this rating

Reviews reach different answers on the same blood fats; effects are small and not seen in Western populations in one analysis.

Form and dose studied

Cinnamon powder or extract, variable doses.

Who was studied

Adults with obesity, metabolic syndrome, diabetes or PCOS.

Limits

Surrogate markers; heterogeneity.

Why researchers looked

People take cinnamon hoping to improve cholesterol.

Traditional use

Cinnamon bark has long been used as a spice and in traditional medicine in South Asia, China and elsewhere; the diabetes use is mainly modern.

Proposed mechanism Preliminary mechanism

Same early lab ideas as above.

A proposed mechanism does not show that the effect happens in people.

Cassia contains coumarin, which can harm the liver in sensitive people (see Safety). Ceylon has little coumarin.

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Blood pressure

Low certainty

Pooled analyses suggest a small drop in blood pressure, mostly in people with diabetes or overweight. Reviews disagree on the size, and it is not shown to help people with diagnosed high blood pressure.

7 studiesCinnamon capsules or powder, mostly 1.2 to 3 g a day.

Studies, doses and limits

What the trials found

Hadi 2020 (9 trials, 641 people) found systolic -5.17 mmHg and diastolic -3.36 mmHg, mainly in trials of 2 g a day or less, lasting over 8 weeks, in people with BMI 30 or more. Ghavami 2021 (8 trials, 582 people) found systolic -0.61 mmHg (not significant) and diastolic -0.93 mmHg. Jamali 2020 (9 articles, people with type 2 diabetes) found a drop in both. Single trials: Wainstein 2011 (59 people) saw a systolic fall that disappeared after adjusting for starting pressure and was put down to regression to the mean; Azimi 2016 (204 people) found no difference from tea alone; Delgadillo-Centeno 2023 found no change. The 2025 meta-analysis of 49 studies reported lower systolic and diastolic pressure in standardised units.

Results

From no change to about 5 mmHg in the top number.

Effect sizes as reported

Hadi: SBP -5.17 mmHg (CI -9.35 to -0.99), DBP -3.36 (CI -5.67 to -1.04); Ghavami: SBP -0.61 (CI -1.36 to 0.14), DBP -0.93 (CI -1.55 to -0.32).

Why this rating

Reviews of almost the same trials disagree on systolic pressure, trials are small and mostly not in people with high blood pressure.

Form and dose studied

Cinnamon capsules or powder, mostly 1.2 to 3 g a day.

Who was studied

Adults with type 2 diabetes, overweight or obesity.

Limits

Few trials in hypertension; authors recommend better trials.

Why researchers looked

Blood pressure was measured in several cinnamon trials.

Traditional use

Cinnamon bark has long been used as a spice and in traditional medicine in South Asia, China and elsewhere; the diabetes use is mainly modern.

Proposed mechanism Preliminary mechanism

Lab work suggests cinnamon compounds may relax blood vessels. This is early and not proven in people.

A proposed mechanism does not show that the effect happens in people.

May add to blood pressure medicines; tell your prescriber.

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PCOS: blood sugar, insulin and body measures

Low certainty

In women with polycystic ovary syndrome (PCOS), pooled small trials suggest lower fasting sugar and insulin resistance. Weight changes are small. Trials are few.

7 studiesCinnamon powder 1.5 g a day (single-herb trials).

Studies, doses and limits

What the trials found

Heydarpour 2020 pooled 5 trials: fasting glucose -5.32 mg/dL, insulin -4.10, HOMA-IR -0.69, no change in weight or BMI. Heshmati 2021 (5 trials) found HOMA-IR SMD -0.84 (CI -1.52 to -0.16). Xiaomei 2024 (12 trials) found weight -0.47 kg, fasting sugar -7.72 mg/dL and lower total and LDL cholesterol. Trial level: Hajimonfarednejad 2018 (66 women, 1.5 g cinnamon powder a day, 12 weeks) found lower fasting insulin (p 0.024) and HOMA-IR (p 0.014) than placebo, but no difference in testosterone, DHEA-S or other measures. Peivandi 2024 (39 women, 1.5 g a day, 6 months) found no difference in BMI, lipids, insulin resistance or androgens. Combination products (marjoram tea; DLBS3233 with another plant) cannot be credited to cinnamon.

Results

Fasting glucose about 5 to 8 mg/dL lower; HOMA-IR about 0.7 lower in pooled results.

Effect sizes as reported

Heydarpour: fasting glucose -5.32 (CI -10.46 to -0.17); Xiaomei: -7.72 mg/dL; Hajimonfarednejad: fasting insulin p 0.024; Peivandi: no significant change.

Why this rating

Five to twelve small trials, high heterogeneity (I2 91 percent for fasting sugar), a pilot with null results.

Form and dose studied

Cinnamon powder 1.5 g a day (single-herb trials).

Who was studied

Women with PCOS, many overweight, some on other treatments.

Limits

No data on periods, ovulation or pregnancy rates.

Why researchers looked

Insulin resistance drives many PCOS symptoms, so cinnamon has been tried.

Traditional use

Not a documented traditional use for PCOS in the sources read.

Proposed mechanism Preliminary mechanism

Same insulin-related lab ideas as for diabetes; none shown directly in PCOS ovaries.

A proposed mechanism does not show that the effect happens in people.

Not for use during pregnancy in medicinal amounts; see Safety.

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PCOS: hormones and ovaries

Not enough evidence

For hormones (testosterone, AMH) and ovary size, evidence is thin and mixed. One pilot found a smaller ovary volume; another found no androgen change.

3 studies1.5 g a day powder; combination tea.

Studies, doses and limits

What the trials found

Hajimonfarednejad 2018 found no difference in testosterone or DHEA-S versus placebo. Peivandi 2024 (39 women, 6 months) found differences in ovarian volume and abdominal subcutaneous fat but no change in androgens. Majeed 2025, a pilot of marjoram plus cinnamon tea (60 women, 36 completed), saw hormone changes in both groups; it is a combination and cannot be credited to cinnamon.

Results

No clear effect.

Effect sizes as reported

Not quantified in abstracts.

Why this rating

Two small trials with different answers and a combination pilot.

Form and dose studied

1.5 g a day powder; combination tea.

Who was studied

Women with PCOS.

Limits

No fertility outcomes.

Why researchers looked

PCOS involves high male-type hormones and ovary changes.

Proposed mechanism Pharmacological theory

None established.

A proposed mechanism does not show that the effect happens in people.

Cassia contains coumarin, which can harm the liver in sensitive people (see Safety). Ceylon has little coumarin.

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Body weight and waist

Low certainty

Pooled analyses find very small reductions in weight and BMI with cinnamon, under about 1 kg on average. This is too small to matter much on its own.

6 studiesCinnamon powder or extract, doses vary.

Studies, doses and limits

What the trials found

Yazdanpanah 2020 (21 trials, 1,480 people) found weight -0.92 kg, BMI -0.40 kg/m2 and waist-hip ratio -0.02, with waist and fat mass not significant. An umbrella analysis of 7 meta-analyses found weight -0.67 kg and BMI -0.45. Namazi 2019 and Jamali 2020 found no significant weight, BMI or waist change in people with type 2 diabetes. Xiaomei 2024 found -0.47 kg in PCOS. In a crossover trial of 21 healthy adults, a cinnamon drink reduced fullness and slightly raised food eaten at the next meal. One report links cinnamon taken for weight loss to liver injury in a single woman (see Safety).

Results

Under 1 kg in pooled results.

Effect sizes as reported

Yazdanpanah: weight -0.92 kg (CI -1.51 to -0.33; I2 84%); BMI -0.40.

Why this rating

Statistically detectable but tiny change, high heterogeneity, and a small appetite trial that went the wrong way.

Form and dose studied

Cinnamon powder or extract, doses vary.

Who was studied

Adults, many with diabetes or PCOS.

Limits

The umbrella paper's title overstates what the numbers show.

Why researchers looked

Cinnamon is sold for weight loss.

Traditional use

Cinnamon bark has long been used as a spice and in traditional medicine in South Asia, China and elsewhere; the diabetes use is mainly modern.

Proposed mechanism Animal research

Some animal work suggests cassia extract may raise heat production in brown fat; no human proof.

A proposed mechanism does not show that the effect happens in people.

Cassia contains coumarin, which can harm the liver in sensitive people (see Safety). Ceylon has little coumarin.

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Inflammation and oxidative stress markers

Low certainty

Pooled analyses find lower CRP (an inflammation marker) with cinnamon, but a careful trial in people with diabetes found no change. Evidence is low.

5 studiesCinnamon powder 1.5 to 4 g a day.

Studies, doses and limits

What the trials found

Vallianou 2019 (6 studies, 285 people) found CRP -0.81 mg/L. Zhu 2020 (12 trials) found CRP -2.22 mg/L, MDA lower and total antioxidant capacity higher. The umbrella analysis (Sarmadi 2023) found no significant effect on CRP or MDA. Davari 2019 (44 people with type 2 diabetes, 3 g for 8 weeks) found no benefit on hs-CRP, IL-6, TNF-alpha or SIRT1. Jafari 2025 reported lower CRP in standardised units.

Results

CRP about 1 to 2 mg/L lower in some analyses; not seen in others.

Effect sizes as reported

Vallianou: CRP -0.81 mg/L (CI -1.36 to -0.26); Zhu: -2.22 mg/L (CI -3.74 to -0.69); Sarmadi: CRP -1.33 (CI -2.66 to 0.00, p 0.051).

Why this rating

Small number of trials; conflicting reviews; best single trial null.

Form and dose studied

Cinnamon powder 1.5 to 4 g a day.

Who was studied

Adults with diabetes, metabolic disorders or PCOS.

Limits

Marker only, not symptoms.

Why researchers looked

Cinnamon polyphenols are antioxidants in the lab.

Traditional use

Cinnamon bark has long been used as a spice and in traditional medicine in South Asia, China and elsewhere; the diabetes use is mainly modern.

Proposed mechanism Laboratory research

Cinnamaldehyde and polyphenols reduce inflammation signals in cells and animals.

A proposed mechanism does not show that the effect happens in people.

Cassia contains coumarin, which can harm the liver in sensitive people (see Safety). Ceylon has little coumarin.

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Painful periods (primary dysmenorrhoea)

Very low certainty

A small meta-analysis suggests cinnamon may ease period pain. A Cochrane review could not draw any conclusion about cinnamon.

2 studiesNot given.

Studies, doses and limits

What the trials found

Xu 2020 (9 studies, 647 women, pooled cinnamon, fennel and ginger) reported less pain intensity and shorter pain duration with cinnamon versus placebo; the numbers in the abstract are hard to interpret and the authors ask for more studies. The Cochrane review on supplements for painful periods (Pattanittum 2016) said data on cinnamon versus placebo were unsuitable for analysis.

Results

Not clearly quantifiable.

Effect sizes as reported

Xu: cinnamon pain WMD 1.815 (CI 1.330 to 2.301) as reported.

Why this rating

Few trials; the best-quality review could not analyse cinnamon.

Form and dose studied

Not given.

Who was studied

Young women with period pain.

Limits

Small trials; unclear products.

Why researchers looked

Cinnamon is a traditional remedy for cramps.

Traditional use

Traditionally used for menstrual complaints, per the reviews read.

Proposed mechanism Pharmacological theory

Cinnamon may relax muscle in lab studies; unproven for periods.

A proposed mechanism does not show that the effect happens in people.

Not for use in pregnancy in medicinal amounts.

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Digestion: diarrhoea, bloating and indigestion

Very low certainty

One trial of a cassia water extract found slower gut transit in people with diarrhoea. A Cochrane review found cinnamon oil made little or no difference to indigestion. Traditional use for gas and cramps is recognised in Europe.

3 studiesCassia water extract 2.4 g a day; cinnamon oil.

Studies, doses and limits

What the trials found

Park 2023 (70 people with diarrhoea symptoms, cassia water extract capsules for 8 weeks) found slower colonic transit (p 0.019) and changes in gut bacteria and stool chemicals; the abstract does not give a symptom score. The Cochrane review of non-Chinese herbal medicines for functional dyspepsia (Baez 2023) found cinnamon oil may make little or no difference (one study, 51 people, SMD 0.38, CI -0.17 to 0.94, low certainty). In Zelicha 2024, 4 g of cinnamon a day caused no differences in digestive symptoms from placebo.

Results

No clear benefit.

Effect sizes as reported

Baez: cinnamon oil SMD 0.38 (CI -0.17 to 0.94).

Why this rating

One small trial with indirect results and one Cochrane null.

Form and dose studied

Cassia water extract 2.4 g a day; cinnamon oil.

Who was studied

People with diarrhoea or functional dyspepsia.

Limits

No symptom data in the abstract of the diarrhoea trial.

Why researchers looked

Cinnamon is a classic digestive spice.

Traditional use

The EU lists cinnamon bark oil as a traditional remedy for mild spasmodic stomach and bowel complaints, bloating and wind (monograph not fully read).

Proposed mechanism Animal research

Cinnamon oil relaxes gut muscle and affects gut bacteria in lab and animal studies.

A proposed mechanism does not show that the effect happens in people.

Cassia has coumarin; see Safety.

^{48 8 73}

Mouth health and germs (antimicrobial effects)

Very low certainty

In test tubes cinnamon oil and extracts kill many germs. In people, one small trial found a cinnamon oil mouthwash helped oral thrush about as well as an antifungal drug. Cinnamon can also irritate the mouth (see Safety).

4 studies0.5 mg/mL oil mouthwash (trial).

Studies, doses and limits

What the trials found

Araujo 2021 (36 people with oral thrush) compared Cinnamomum zeylanicum essential oil mouthwash and spray (0.5 mg/mL) with nystatin for 15 days: both improved signs, and cinnamon cut Candida counts by 61% on the mouth lining and 33% on dentures. A meta-analysis of lab studies (Ezzaky 2023) found cassia and cinnamon extracts inhibited foodborne bacteria such as Salmonella and Bacillus cereus in test tubes. Reviews of dental and antibacterial use (Yanakiev 2020, Vasconcelos 2018) describe mostly lab work.

Results

Candida counts down 33 to 61% in one small trial.

Effect sizes as reported

Araujo: Candida reduced 61% (mucosa), 33% (dentures).

Why this rating

One small head-to-head trial; the rest is test-tube work that does not show benefit in people.

Form and dose studied

0.5 mg/mL oil mouthwash (trial).

Who was studied

People with oral thrush; lab organisms.

Limits

Small; no placebo.

Why researchers looked

Cinnamon oil is widely tested against germs.

Traditional use

Cinnamon bark has long been used as a spice and in traditional medicine in South Asia, China and elsewhere; the diabetes use is mainly modern.

Proposed mechanism Laboratory research

Cinnamaldehyde damages bacterial and fungal cell walls in the lab.

A proposed mechanism does not show that the effect happens in people.

Cinnamon oil can burn skin and mouth if used undiluted (see Safety).

^{76 14 68 61}

Connections to the rest of health

How Cinnamon connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.

Explore every connection: goals, body systems, organs, symptoms, genes

Kind of connection Connected to Search

A. Wellness goals

Connected to	Kind of connection	Evidence status	Context	Studies
Blood Sugar Balance	Potential benefit	Mixed findings	Long-term blood sugar (HbA1c) in type 2 diabetes: HbA1c is the three-month blood sugar average. Some pooled analyses find a small drop with cinnamon and others find none. The size, where found, is small (roughly 0.1 to 0.6 points). Reviewers disagree, so the evidence is mixed. Fasting blood sugar in type 2 diabetes: Most pooled analyses find fasting blood sugar is lower with cinnamon, on average about 10 to 25 mg/dL. The studies are small, disagree a lot and are of uneven quality, so the certainty is low.	^{2 3 45 13 32 42 77 33 72 35 59 36 55 31 11 44 64 18 5 63 52 6 73 54 12 22 21 66 20 50 39 51}
Metabolic Health	Potential benefit	Mixed findings	Long-term blood sugar (HbA1c) in type 2 diabetes: HbA1c is the three-month blood sugar average. Some pooled analyses find a small drop with cinnamon and others find none. The size, where found, is small (roughly 0.1 to 0.6 points). Reviewers disagree, so the evidence is mixed. Fasting blood sugar in type 2 diabetes: Most pooled analyses find fasting blood sugar is lower with cinnamon, on average about 10 to 25 mg/dL. The studies are small, disagree a lot and are of uneven quality, so the certainty is low.	^{2 3 45 13 32 42 77 33 72 35 59 36 55 31 11 44 64 18 73 63 17 65 69 30 27 66 57}
Weight Management	Potential benefit	Low certainty	Metabolic syndrome: One 16-week trial in India found many improvements with cinnamon in people with metabolic syndrome, larger than other trials usually report. It has not been confirmed by independent trials. Body weight and waist: Pooled analyses find very small reductions in weight and BMI with cinnamon, under about 1 kg on average. This is too small to matter much on its own.	^{17 65 69 30 45 27 66 57}
Heart Health	Potential benefit	Low certainty	Metabolic syndrome: One 16-week trial in India found many improvements with cinnamon in people with metabolic syndrome, larger than other trials usually report. It has not been confirmed by independent trials. Blood fats (cholesterol, triglycerides) in type 2 diabetes: Pooled trials in people with type 2 diabetes find lower triglycerides and total cholesterol, and sometimes LDL, with cinnamon. Effects are small and the trials disagree.	^{17 65 3 26 77 13 44 55 71 38 56 32 22 19 15 27 62 4 12 25}
Memory Support	Preliminary mechanism	Not enough evidence	Memory, thinking and Alzheimer disease: We found no human trial of cinnamon for memory or thinking. Lab and animal work suggests cinnamon compounds may affect brain proteins linked to Alzheimer disease, but this has not been tested in people.	⁴¹
Brain Health	Preliminary mechanism	Not enough evidence	Memory, thinking and Alzheimer disease: We found no human trial of cinnamon for memory or thinking. Lab and animal work suggests cinnamon compounds may affect brain proteins linked to Alzheimer disease, but this has not been tested in people.	⁴¹
Cognitive Performance	Preliminary mechanism	Not enough evidence	Memory, thinking and Alzheimer disease: We found no human trial of cinnamon for memory or thinking. Lab and animal work suggests cinnamon compounds may affect brain proteins linked to Alzheimer disease, but this has not been tested in people.	⁴¹
Cholesterol Balance	Potential benefit	Low certainty	Blood fats (cholesterol, triglycerides) in type 2 diabetes: Pooled trials in people with type 2 diabetes find lower triglycerides and total cholesterol, and sometimes LDL, with cinnamon. Effects are small and the trials disagree. Blood fats in adults generally and in metabolic syndrome: Across all adults, pooled lipid results are small and mixed. Triglycerides and total cholesterol fall slightly in some reviews; LDL and HDL change little.	^{3 26 77 13 44 55 71 38 65 56 32 22}
Blood Pressure Support	Potential benefit	Low certainty	Blood pressure: Pooled analyses suggest a small drop in blood pressure, mostly in people with diabetes or overweight. Reviews disagree on the size, and it is not shown to help people with diagnosed high blood pressure.	^{19 15 27 62 4 12 25}
Womens Wellness	Potential benefit	Low certainty	PCOS: blood sugar, insulin and body measures: In women with polycystic ovary syndrome (PCOS), pooled small trials suggest lower fasting sugar and insulin resistance. Weight changes are small. Trials are few. Painful periods (primary dysmenorrhoea): A small meta-analysis suggests cinnamon may ease period pain. A Cochrane review could not draw any conclusion about cinnamon.	^{22 21 66 20 50 39 51 67 49}
Hormone Balance	Potential benefit	Low certainty	PCOS: blood sugar, insulin and body measures: In women with polycystic ovary syndrome (PCOS), pooled small trials suggest lower fasting sugar and insulin resistance. Weight changes are small. Trials are few.	^{22 21 66 20 50 39 51}
Womens Wellness	Preliminary mechanism	Not enough evidence	PCOS: hormones and ovaries: For hormones (testosterone, AMH) and ovary size, evidence is thin and mixed. One pilot found a smaller ovary volume; another found no androgen change.	^{20 50 39}
Hormone Balance	Preliminary mechanism	Not enough evidence	PCOS: hormones and ovaries: For hormones (testosterone, AMH) and ovary size, evidence is thin and mixed. One pilot found a smaller ovary volume; another found no androgen change.	^{20 50 39}
Fertility Support	Preliminary mechanism	Not enough evidence	PCOS: hormones and ovaries: For hormones (testosterone, AMH) and ovary size, evidence is thin and mixed. One pilot found a smaller ovary volume; another found no androgen change.	^{20 50 39}
Inflammation Balance	Biological association	Low certainty	Inflammation and oxidative stress markers: Pooled analyses find lower CRP (an inflammation marker) with cinnamon, but a careful trial in people with diabetes found no change. Evidence is low.	^{60 75 56 10 25}
Healthy Aging	Biological association	Low certainty	Inflammation and oxidative stress markers: Pooled analyses find lower CRP (an inflammation marker) with cinnamon, but a careful trial in people with diabetes found no change. Evidence is low.	^{60 75 56 10 25}
Calm Relaxation	Potential benefit	Very low certainty	Painful periods (primary dysmenorrhoea): A small meta-analysis suggests cinnamon may ease period pain. A Cochrane review could not draw any conclusion about cinnamon.	^{67 49}
Digestive Support	Traditional use	Very low certainty	Digestion: diarrhoea, bloating and indigestion: One trial of a cassia water extract found slower gut transit in people with diarrhoea. A Cochrane review found cinnamon oil made little or no difference to indigestion. Traditional use for gas and cramps is recognised in Europe.	^{48 8 73}
Gut Health	Traditional use	Very low certainty	Digestion: diarrhoea, bloating and indigestion: One trial of a cassia water extract found slower gut transit in people with diarrhoea. A Cochrane review found cinnamon oil made little or no difference to indigestion. Traditional use for gas and cramps is recognised in Europe.	^{48 8 73}
Immune Support	Preliminary mechanism	Very low certainty	Mouth health and germs (antimicrobial effects): In test tubes cinnamon oil and extracts kill many germs. In people, one small trial found a cinnamon oil mouthwash helped oral thrush about as well as an antifungal drug. Cinnamon can also irritate the mouth (see Safety).	^{76 14 68 61}

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Endocrine system	Drug or supplement interaction	Low certainty	May add to diabetes medicines; low-sugar risk is theoretical. Preparation or compound: Cinnamon supplements	^{36 35 12}
Immune system	Adverse effect or risk	Low certainty	Allergic-type mouth inflammation from gum, sweets and toothpaste. Preparation or compound: Cinnamaldehyde flavouring	^{29 9}
Reproductive system	Contraindication	Low certainty	NCCIH: larger Ceylon amounts unsafe in pregnancy; no nursing data; rat offspring effects. Preparation or compound: Medicinal amounts, pregnancy and breastfeeding	^{83 47 46}
Endocrine System	Biological association	Mixed findings	Studied for: Long-term blood sugar (HbA1c) in type 2 diabetes Studied for: Fasting blood sugar in type 2 diabetes	^{2 3 45 13 32 42 77 33 72 35 59 36 55 31 11 44 64 18 5 63 52 6 73 54 12 17 65 26 71 38 56 22 21 66 20 50 39 51}
Metabolism Weight	Biological association	Mixed findings	Studied for: Long-term blood sugar (HbA1c) in type 2 diabetes Studied for: Fasting blood sugar in type 2 diabetes	^{2 3 45 13 32 42 77 33 72 35 59 36 55 31 11 44 64 18 5 63 52 6 73 12 17 65 26 71 38 56 22 69 30 27 66 57}
Nervous System	Biological association	Not enough evidence	Studied for: Memory, thinking and Alzheimer disease	⁴¹
Cardiovascular System	Biological association	Low certainty	Studied for: Blood pressure	^{19 15 27 62 4 12 25}
Reproductive System	Biological association	Low certainty	Studied for: PCOS: blood sugar, insulin and body measures Studied for: PCOS: hormones and ovaries	^{22 21 66 20 50 39 51 67 49}
Immune System	Biological association	Low certainty	Studied for: Inflammation and oxidative stress markers Studied for: Mouth health and germs (antimicrobial effects)	^{60 75 56 10 25 76 14 68 61}
Digestive System	Biological association	Very low certainty	Studied for: Digestion: diarrhoea, bloating and indigestion Studied for: Mouth health and germs (antimicrobial effects)	^{48 8 73 76 14 68 61}

C. Body parts and organs

Connected to	Kind of connection	Evidence status	Context	Studies
Liver	Adverse effect or risk	Low certainty	Rare liver injury case reports; coumarin intake limit in Europe; a meta-analysis of enzyme trials was neutral. Preparation or compound: Cassia cinnamon (coumarin)	^{23 7 70 1 43}
Gut	Adverse effect or risk	Low certainty	Bloating, heartburn and nausea. Preparation or compound: Cinnamon	^{47 33}
Lungs	Adverse effect or risk	Low certainty	Cellulose fibres can cause lasting inflammation when breathed in. Preparation or compound: Dry ground cinnamon, inhaled	^{28 16}

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
HbA1c (three-month blood sugar average, %)	Biological association	Mixed findings	Measured in trials: mixed. A lab change is not the same as a health benefit.	^{2 3 45 72 32 35 12}
Fasting blood glucose	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{3 45 77 72 33 44 59}
HOMA-IR (insulin resistance estimate)	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{13 77 72 64}
Blood sugar after eating or a glucose drink	Biological association	Mixed findings	Measured in trials: mixed. A lab change is not the same as a health benefit.	^{77 5 63 52 73}
Fasting insulin	Biological association	Low certainty	Measured in trials: no-change. A lab change is not the same as a health benefit.	^{42 72 59}
LDL cholesterol (mg/dL)	Biological association	Mixed findings	Measured in trials: mixed. A lab change is not the same as a health benefit.	^{26 3 38 44 32}
HDL cholesterol (mg/dL)	Biological association	Low certainty	Measured in trials: mixed. A lab change is not the same as a health benefit.	^{3 26 56}
Triglycerides (mg/dL)	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{38 26 65 56}
Total cholesterol (mg/dL)	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{38 26 65 56}
Systolic blood pressure (top number, mmHg)	Biological association	Low certainty	Measured in trials: mixed. A lab change is not the same as a health benefit.	^{19 15 62}
Diastolic blood pressure (bottom number, mmHg)	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{19 15}
Body weight and BMI	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{69 30 45}
C-reactive protein (CRP, mg/L)	Biological association	Low certainty	Measured in trials: mixed. A lab change is not the same as a health benefit.	^{60 75 56 10}
Testosterone and other androgens (PCOS)	Biological association	Low certainty	Measured in trials: no-change. A lab change is not the same as a health benefit.	^{20 50}

J. Genes, receptors and enzymes

Connected to	Kind of connection	Evidence status	Context	Studies
Pancreatic alpha-amylase	Preliminary mechanism	In vitro	Inhibited by a Ceylon extract in a test tube.	⁵
SLC2A4 (GLUT4)	Preliminary mechanism	In vitro	Glucose transporter moved to the cell membrane by C. zeylanicum in cell studies, as summarised by a review.	⁵⁴
PPARG and other PPARs	Preliminary mechanism	Animal	Named among cinnamaldehyde's pathways in animals.	⁷⁴
PTPN1 (PTP1B)	Preliminary mechanism	In vitro	Cinnamaldehyde appears to regulate this insulin-signalling brake in lab work.	⁷⁴
TRPA1	Preliminary mechanism	Animal	Cinnamaldehyde's TRPA1 route to ghrelin signalling is reported in animals.	⁷⁴

K. Biological pathways

Connected to	Kind of connection	Evidence status	Context	Studies
AMPK signalling	Preliminary mechanism	Animal	Cinnamaldehyde acts via AMPK in diabetic animal models.	⁷⁴
PI3K/IRS-1 insulin signalling	Preliminary mechanism	Animal	Cinnamaldehyde improved insulin sensitivity in animals through this pathway.	⁷⁴
Keap1-Nrf2 antioxidant response	Preliminary mechanism	In vitro	Cinnamaldehyde acts via Nrf2 in lab models.	⁷⁴
NF-kB inflammation signalling	Preliminary mechanism	Human	Plasma NF-kB differed between cinnamon and placebo in a 44-person trial while inflammation markers did not.	¹⁰
Tau and amyloid-beta	Preliminary mechanism	In vitro	Aggregation blocked in lab and animal models.	⁴¹

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Cinnamaldehyde	Biological association	Animal	Gives cinnamon its flavour and is the main compound tested in the lab. Animal studies show glucose and fat lowering through several pathways; it is changed in the body to cinnamyl alcohol, methyl cinnamate and cinnamic acid; it can sensitise the mouth and skin in some people. Preparation or compound: Bark (both species); bark oil	^{74 61 29 79}
Coumarin	Biological association	Human	Liver-toxic in a sensitive subgroup of people (as a drug); EFSA and BfR TDI 0.1 mg/kg body weight a day; European limits on cinnamon foods. Preparation or compound: Bark; far higher in cassia	^{78 1 24 53}
Eugenol	Biological association	In vitro	Aromatic and antimicrobial compound in lab studies; its role in human effects has not been shown. Preparation or compound: Bark; present at 5.77% of the profile in Ceylon in one comparison	^{53 47}
Cinnamic acid	Biological association	In vitro	Antibacterial in lab studies; a metabolite of cinnamaldehyde. Preparation or compound: Bark; also a body metabolite of cinnamaldehyde	^{61 74}
Procyanidin A2 and related polyphenols	Biological association	In vitro	Cinnamon polyphenols are described as antioxidant and as inhibiting tau aggregation in lab models (Momtaz 2018). A specific compound's role in human effects is not shown. Preparation or compound: Bark	⁴¹
Cinnamyl alcohol	Biological association	Animal	Named as a metabolite of cinnamaldehyde (Zhu 2017). Preparation or compound: Bark; also a metabolite of cinnamaldehyde	⁷⁴

Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 25, 2026).

Evidence at a glance: what changed in 14 lab markers

Tap a number to show only those markers. Counts are markers, not people.

Hormonal1 Metabolic413 Inflammatory1 Other22

The evidence

The research centre for Cinnamon. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).

How we rate evidence

High certainty

Several well-run trials or reviews agree; further research is unlikely to change the picture much.

Moderate certainty

Good trials point the same way, but some doubt remains.

Low certainty

Small, short or inconsistent trials. The finding could change with better research.

Very low certainty

Very little or very weak human data. Treat as a possibility only.

Mixed findings

Trials or reviews disagree with each other.

Not enough evidence

Not enough human research to say either way.

Evidence against

Good research found no benefit, or found harm.

We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We searched PubMed and read abstracts (not full texts) for nearly all studies. We read summaries of the NCCIH cinnamon page and the German BfR coumarin FAQ, checked plant names in GBIF and the NCBI taxonomy, and compounds in PubChem. Some sources were not verified: the EMA/HMPC monograph's safety sections, the EFSA coumarin opinion, the full LiverTox page (its likelihood score was not seen), the FDA statement (known only through LactMed), and the Commission E and WHO monographs. The abstract of one Pediatrics paper on the cinnamon challenge was not available. Certainty ratings are the compiler's own reading, not formal grades. No study is cited that we could not verify. One often-cited 2003 diabetes trial carries a journal Expression of Concern and is not relied on.

Study library: every study we checked 83

Design Research type Plant part Year from Search

Study	Design	People	Product, dose, length	Result
Abraham 2010 Toxicology and risk assessment of coumarin: focus on human data. Molecular nutrition & food research · PMID 20024932 · DOI	Review	Human and animal toxicity data on coumarin; German survey of over 1,000 people on Christmas cassia intake	Coumarin (pure compound, as drug) and cassia cinnamon exposure bark (cassia) TDI 0.1 mg per kg body weight per day	Coumarin can harm the liver; a subgroup of people is more sensitive than test animals. A TDI of 0.1 mg/kg/day was derived from human drug data and matches EFSA. Heavy cassia eaters can reach the TDI. TDI 0.1 mg/kg body weight a day Methods, limits and funding Outcomes: Liver toxicity, tolerable daily intake Limitations: Only the abstract was read. Based on coumarin as a drug, not on cinnamon. Read: abstract
Akilen 2012 Cinnamon in glycaemic control: Systematic review and meta analysis. Clinical nutrition (Edinburgh, Scotland) · PMID 22579946 · DOI	Meta-analysis	435 Adults with type 2 diabetes; 6 trials	Cinnamon (1 to 6 g a day) bark (as reported) 1 to 6 g a day 40 days to 4 months · vs Control	Small but statistically significant drops in HbA1c and fasting glucose. HbA1c -0.09 percentage points; fasting glucose -0.84 mmol/L (HbA1c 0.04 to 0.14; fasting glucose 0.66 to 1.02) Methods, limits and funding Outcomes: HbA1c and fasting plasma glucose Limitations: Only the abstract was read. Only 6 trials. The HbA1c drop is tiny. Searched to August 2011. Read: abstract
Allen 2013 Cinnamon use in type 2 diabetes: an updated systematic review and meta-analysis. Annals of family medicine · PMID 24019277 · DOI	Meta-analysis	543 Adults with type 2 diabetes; 10 randomized trials	Cinnamon (120 mg to 6 g a day) bark (as reported) 120 mg to 6 g a day 4 to 18 weeks · vs Control	Fasting glucose, total cholesterol, LDL and triglycerides fell and HDL rose, but HbA1c did not change significantly. Fasting glucose -24.59 mg/dL; total cholesterol -15.60; LDL -9.42; triglycerides -29.59; HDL +1.66; HbA1c -0.16% (Fasting glucose -40.52 to -8.67; HbA1c -0.39 to 0.02) Methods, limits and funding Outcomes: Fasting plasma glucose, HbA1c, lipids Limitations: Only the abstract was read. Heterogeneity was high (I2 66 to 95 percent for all but HDL). Searched to February 2012. Authors say the preferred dose and duration are unclear. Read: abstract
Azimi 2016 Effect of cinnamon, cardamom, saffron and ginger consumption on blood pressure and a marker of endothelial function in patients with type 2 diabetes mellitus: A randomized controlled clinical trial. Blood pressure · PMID 26758574 · DOI	Controlled trial	204 Adults with type 2 diabetes in Iran	Cinnamon with black tea (compared with cardamom, saffron, ginger) 3 g cinnamon with tea 8 weeks · vs Tea alone	No difference between plants and control for blood pressure, ICAM-1 or body measures. No significant between-group difference Methods, limits and funding Outcomes: Blood pressure, ICAM-1, body measures Limitations: Only the abstract was read. Read: abstract
Beejmohun 2014 Acute effect of Ceylon cinnamon extract on postprandial glycemia: alpha-amylase inhibition, starch tolerance test in rats, and randomized crossover clinical trial in healthy volunteers. BMC complementary and alternative medicine · PMID 25249234 · DOI	Controlled trial	18 Healthy volunteers (crossover); plus rat and test-tube work	Ceylon cinnamon hydro-alcoholic extract (CCE) bark (extract) 1 g (single dose) Single test · vs Placebo	Lower glucose in the first hour; whole 2-hour change not significant; no extra insulin; no adverse effects. Glucose AUC 0-60 min -21.2% (p<0.05); AUC 0-120 min -14.8% (p=0.15) Methods, limits and funding Outcomes: Blood glucose and insulin for 2 hours after a meal Limitations: Only the abstract was read. Healthy people, one dose. Registered NCT02074423. Funding not in abstract. Read: abstract
Bernardo 2015 Effect of Cinnamon Tea on Postprandial Glucose Concentration. Journal of diabetes research · PMID 26258147 · DOI	Controlled trial	Adults without diabetes	Cinnamon tea (Cinnamomum burmannii) bark Not given in abstract Single test · vs Glucose drink alone	Slightly lower glucose; lower peak and peak variation (p<0.05). p<0.05 for maximum glucose Methods, limits and funding Outcomes: After-meal glucose Limitations: Only the abstract was read. Sample size not in abstract. Different species (C. burmannii, Indonesian cassia). Read: abstract
Brancheau 2015 Do cinnamon supplements cause acute hepatitis? The American journal of case reports · PMID 25923145 · DOI	Case report	1 73-year-old woman, also taking a statin	Cinnamon supplement (species not stated) About 1 week	Abdominal pain, vomiting, diarrhoea and hepatitis after about a week of cinnamon supplements; both stopped; statin restarted later without trouble. Hepatitis; recovery after stopping Methods, limits and funding Outcomes: Liver tests Limitations: Only the abstract was read. One case, other causes not fully excluded, and a statin was involved. Read: abstract
Báez 2023 Non-Chinese herbal medicines for functional dyspepsia. The Cochrane database of systematic reviews · PMID 37323050 · DOI	Systematic review	People with functional dyspepsia; Cochrane review of 41 trials of non-Chinese herbal medicines	Many herbs including cinnamon oil bark oil Not given in abstract Not given in abstract · vs Placebo	Cinnamon oil may make little or no difference to symptoms (one study of 51 people, low certainty). Cinnamon oil SMD 0.38 (-0.17 to 0.94) Methods, limits and funding Outcomes: Dyspepsia symptoms Limitations: Only the abstract was read. Read: abstract
Calapai 2014 Oral adverse reactions due to cinnamon-flavoured chewing gums consumption. Oral diseases · PMID 24004186 · DOI	Review	Case reports of mouth reactions to cinnamon gum	Cinnamon-flavoured gum, toothpaste, candy, mouthwash flavouring	Contact stomatitis (mouth inflammation from allergy) is the most common reaction and may be missed or mistaken for other mouth problems. Not applicable Methods, limits and funding Outcomes: Oral adverse reactions Limitations: Only the abstract was read. Read: abstract
Davari 2020 Effects of cinnamon supplementation on expression of systemic inflammation factors, NF-kB and Sirtuin-1 (SIRT1) in type 2 diabetes: a randomized, double blind, and controlled clinical trial. Nutrition journal · PMID 31901246 · DOI	Controlled trial	44 Adults with type 2 diabetes in Iran; 39 finished	Cinnamon supplement 3 g a day 8 weeks · vs Placebo	No benefit on hs-CRP, TNF-alpha, IL-6 or SIRT1. NF-kB differed between groups (p 0.02); authors conclude no beneficial effect overall. hs-CRP p 0.29; TNF-alpha p 0.27; IL-6 p 0.52; SIRT1 p 0.51; NF-kB p 0.02 Methods, limits and funding Outcomes: hs-CRP, IL-6, TNF-alpha, NF-kB, SIRT1 Limitations: Only the abstract was read. Funding and conflicts: Authors declare no competing interests Read: abstract
Davis 2011 Cinnamon intake lowers fasting blood glucose: meta-analysis. Journal of medicinal food · PMID 21480806 · DOI	Meta-analysis	People with type 2 diabetes or prediabetes; 8 placebo-controlled trials	Cinnamon or cinnamon extract bark (as reported) Not given in abstract Not given in abstract · vs Placebo	Fasting glucose was lower with cinnamon or extract. Fasting glucose -0.49 mmol/L (plus or minus 0.2) Methods, limits and funding Outcomes: Fasting blood glucose Limitations: Only the abstract was read. Searched to May 2010; standard error given instead of a confidence interval. Read: abstract
Delgadillo-Centeno 2023 Cinnamomum cassia on Arterial Stiffness and Endothelial Dysfunction in Type 2 Diabetes Mellitus: Outcomes of a Randomized, Double-Blind, Placebo-Controlled Clinical Trial. Journal of medicinal food · PMID 37262194 · DOI	Controlled trial	18 Adults with type 2 diabetes of one year or less, taking metformin	Cinnamomum cassia capsules bark 3,000 mg a day (1,000 mg three times a day) 12 weeks · vs Placebo	Weight, BMI and HbA1c fell; no change in arterial stiffness, vessel function, fasting glucose, blood pressure or lipids. HbA1c 53 to 45 mmol/mol (p 0.036); weight 81.4 to 79.9 kg (p 0.037) Methods, limits and funding Outcomes: Arterial stiffness, endothelial function, weight, HbA1c, glucose, lipids, BP Limitations: Only the abstract was read. Only 18 people; within-group tests. Read: abstract
Deyno 2019 Efficacy and safety of cinnamon in type 2 diabetes mellitus and pre-diabetes patients: A meta-analysis and meta-regression. Diabetes research and clinical practice · PMID 31425768 · DOI	Meta-analysis	People with type 2 diabetes or prediabetes; 16 randomized trials	Cinnamon (formulations varied) bark (as reported) Not given in abstract Not given in abstract · vs Placebo	Fasting glucose and HOMA-IR fell; HbA1c and lipids did not change significantly. Fasting glucose -0.545 mmol/L; HOMA-IR -0.714; HbA1c and lipids not significant (Fasting glucose -0.910 to -0.18 (I2 83.6%); HOMA-IR -1.388 to -0.04 (I2 84.4%)) Methods, limits and funding Outcomes: Fasting glucose, HOMA-IR, HbA1c, lipids Limitations: Only the abstract was read. High heterogeneity; authors call for standardised cinnamon products. Read: abstract
Ezzaky 2023 In vitro antimicrobial activity of extracts and essential oils of Cinnamomum, Salvia, and Mentha spp. against foodborne pathogens: A meta-analysis study. Comprehensive reviews in food science and food safety · PMID 37615998 · DOI	Meta-analysis in-vitro	Lab studies against foodborne bacteria	Extracts and essential oils of Cinnamomum, Salvia and Mentha bark (extract and oil) Lab concentrations	Cassia extract and cinnamon showed strong inhibition against some bacteria (Salmonella, Bacillus cereus). Cassia vs Salmonella pooled zone 26.24 mm Methods, limits and funding Outcomes: Inhibition zones and MIC Limitations: Only the abstract was read. Test-tube results; not evidence of benefit in people. Read: abstract
Ghavami 2021 What is the Impact of Cinnamon Supplementation on Blood Pressure? A Systematic Review and Meta-Analysis. Endocrine, metabolic & immune disorders drug targets · PMID 32727334 · DOI	Meta-analysis	582 Adults; 8 randomized trials	Cinnamon supplements bark (as reported) Not given in abstract Varied · vs Placebo	Systolic pressure did not change overall; diastolic fell slightly. Systolic -0.61 mmHg (not significant); diastolic -0.93 mmHg (Systolic -1.36 to 0.14; diastolic -1.55 to -0.32) Methods, limits and funding Outcomes: Systolic and diastolic blood pressure Limitations: Only the abstract was read. Conflicts with the larger systolic drop in another review of nearly the same trials. Read: abstract
Grant-Alfieri 2013 Ingesting and aspirating dry cinnamon by children and adolescents: the "cinnamon challenge". Pediatrics · PMID 23610205 · DOI	Review	Children and teenagers who swallow dry ground cinnamon as a dare (the cinnamon challenge)	Dry ground cinnamon bark	Pediatrics paper on the dangers of the cinnamon challenge. Not read Methods, limits and funding Outcomes: Harm from swallowing or breathing in dry cinnamon Limitations: No abstract is available in PubMed; only the title and journal record were read, so we do not repeat its findings. The danger is stated by NCCIH (see s-nccih-cinnamon). Read: summary-only
Gupta Jain 2017 Effect of oral cinnamon intervention on metabolic profile and body composition of Asian Indians with metabolic syndrome: a randomized double -blind control trial. Lipids in health and disease · PMID 28606084 · DOI	Controlled trial	116 Asian Indian adults with metabolic syndrome	Cinnamon capsules (species not stated) 3 g a day 16 weeks · vs Wheat flour capsules	Greater falls in fasting glucose, HbA1c, waist, BMI and other measures; fewer people met metabolic syndrome criteria after. Fasting glucose difference 0.3 mmol/L; HbA1c 2.6 mmol/mol; waist 4.8 cm; BMI 1.3; metabolic syndrome 34.5% vs 5.2% (Fasting glucose 0.2 to 0.5; HbA1c 0.4 to 4.9) Methods, limits and funding Outcomes: Body composition, glucose, HbA1c, blood pressure, lipids Limitations: Only the abstract was read. Registered after recruitment ended (retrospective). Species not named; the large body-measure effects are bigger than most other trials found. Read: abstract
Gutierrez 2016 Cassia Cinnamon Supplementation Reduces Peak Blood Glucose Responses but Does Not Improve Insulin Resistance and Sensitivity in Young, Sedentary, Obese Women. Journal of dietary supplements · PMID 26716656 · DOI	Controlled trial	10 Young sedentary women with obesity (crossover)	Cassia cinnamon bark capsules bark 5 g (single dose) Single test · vs Placebo	Lower 30-minute glucose peak; no change in insulin sensitivity or resistance or overall glucose curve. Peak 140 vs 156 mg/dL (p 0.025) Methods, limits and funding Outcomes: Insulin sensitivity and resistance, glucose after a glucose drink Limitations: Only the abstract was read. Read: abstract
Hadi 2020 The effect of cinnamon supplementation on blood pressure in adults: A systematic review and meta-analysis of randomized controlled trials. Clinical nutrition ESPEN · PMID 32220351 · DOI	Meta-analysis	641 Adults; 9 randomized trials	Cinnamon supplements bark (as reported) Significant mainly at 2 g a day or less Significant mainly beyond 8 weeks · vs Placebo	Both pressures fell modestly; few trials in people with high blood pressure. Systolic -5.17 mmHg; diastolic -3.36 mmHg (Systolic -9.35 to -0.99; diastolic -5.67 to -1.04) Methods, limits and funding Outcomes: Systolic and diastolic blood pressure Limitations: Only the abstract was read. Mostly people with diabetes or overweight; small trials. Funding and conflicts: Authors declare no conflict Read: abstract
Hajimonfarednejad 2018 Insulin resistance improvement by cinnamon powder in polycystic ovary syndrome: A randomized double-blind placebo controlled clinical trial. Phytotherapy research : PTR · PMID 29250843 · DOI	Controlled trial	66 Women with PCOS, all taking a progestin in the last 10 days of the cycle	Cinnamon powder capsules bark powder 1.5 g a day in 3 doses 12 weeks · vs Placebo capsules	Fasting insulin and HOMA-IR fell more than on placebo; LDL fell versus baseline and was lower than placebo (p 0.049); other measures, including testosterone, did not differ. Fasting insulin p 0.024; HOMA-IR p 0.014; LDL p 0.049 Methods, limits and funding Outcomes: Insulin resistance, glucose, lipids, androgens Limitations: Only the abstract was read. Species not stated. Read: abstract
Heshmati 2021 The effect of cinnamon supplementation on glycemic control in women with polycystic ovary syndrome: A systematic review and meta-analysis. Journal of food biochemistry · PMID 33111340 · DOI	Meta-analysis	Women with PCOS; 5 randomized trials	Cinnamon supplements bark (as reported) Not given in abstract Varied · vs Placebo	Lower HOMA-IR with cinnamon. HOMA-IR SMD -0.84 (-1.52 to -0.16) Methods, limits and funding Outcomes: Insulin resistance (HOMA-IR) Limitations: Only the abstract was read. Read: abstract
Heydarpour 2020 Effects of cinnamon on controlling metabolic parameters of polycystic ovary syndrome: A systematic review and meta-analysis. Journal of ethnopharmacology · PMID 32151755 · DOI	Meta-analysis	Women with PCOS; 5 trials	Cinnamon supplements bark (as reported) Not given in abstract Varied · vs Placebo	No change in weight or BMI; fasting glucose, insulin and HOMA-IR fell; LDL, total cholesterol and triglycerides fell and HDL rose. Fasting glucose -5.32 mg/dL; insulin -4.10; HOMA-IR -0.69; weight -0.74 kg (not significant) (Fasting glucose -10.46 to -0.17; HOMA-IR -1.37 to -0.004) Methods, limits and funding Outcomes: Weight, BMI, glucose, insulin, HOMA-IR, lipids Limitations: Only the abstract was read. Only 5 trials; HOMA-IR interval almost reaches zero. Read: abstract
Hoofnagle 2012 Cinnamon. · PMID 42551031	Database entry n/a	LiverTox entry on cinnamon (NIDDK)	Cinnamon bark	Entry says cinnamon as herbal medicine is generally well tolerated but has been implicated in isolated, rare reports of acute liver injury. Not applicable Methods, limits and funding Outcomes: Drug-induced liver injury Limitations: Only the PubMed summary of the entry was read; the full LiverTox page (with its likelihood score) could not be opened. Read: abstract
Iwata 2016 The Relation between Hepatotoxicity and the Total Coumarin Intake from Traditional Japanese Medicines Containing Cinnamon Bark. Frontiers in pharmacology · PMID 27378929 · DOI	Case series	129 Japanese outpatients taking cinnamon-bark Kampo medicine (TJ-125) plus other Kampo	Kampo medicines containing cinnamon bark bark Median coumarin intake 0.113 mg/kg/day (0.049 to 0.541) Retrospective, years 2008 to 2013 · vs Patients below the TDI	76% of patients (98) exceeded the 0.1 mg/kg/day TDI. Liver test abnormalities occurred in 17.3% above and 19.4% below the TDI, not significantly different, and none was traced to cinnamon in individual patients. Abnormal liver tests: 17/98 (17.3%) at or above TDI vs 6/31 (19.4%) below Methods, limits and funding Outcomes: Liver function tests vs coumarin intake Limitations: Only the abstract was read. Retrospective, mixed herbal formulas, no placebo. Coumarin in 1 g cinnamon bark decoction measured at 3.0 mg. Read: abstract
Jafari 2025 The effect of cinnamon supplementation on cardiovascular risk factors in adults: a GRADE assessed systematic review, dose-response and meta-analysis of randomized controlled trials. Journal of health, population, and nutrition · PMID 40611215 · DOI	Meta-analysis	Adults; 49 studies on cardiovascular risk factors	Cinnamon supplements bark (as reported) Dose-response analysed; not given in abstract Not given in abstract · vs Control	Improvements in most measures, reported in standardised units. Fasting glucose SMD -1.28; HbA1c SMD -0.71; LDL SMD -0.71; total cholesterol SMD -1.15; triglycerides SMD -0.91; HDL SMD +0.56; systolic BP SMD -0.85; diastolic BP SMD -1.04; CRP SMD -0.78 (Fasting glucose -1.65 to -0.90; HbA1c -1.02 to -0.40; HDL 0.23 to 0.89) Methods, limits and funding Outcomes: Waist, blood pressure, glucose, insulin, HbA1c, HOMA-IR, CRP, lipids, MDA Limitations: Only the abstract was read. Titled GRADE-assessed but the abstract gives no GRADE ratings. Standardised effect sizes this large are unusual for a spice and likely reflect small, varied trials. Funding and conflicts: Authors declare no conflicts Read: abstract
Jamali 2020 The effect of cinnamon supplementation on lipid profiles in patients with type 2 diabetes: A systematic review and meta-analysis of clinical trials. Complementary therapies in medicine · PMID 33220625 · DOI	Meta-analysis	1025 Adults with type 2 diabetes; 16 studies	Cinnamon supplements bark (as reported) Not given in abstract Varied · vs Placebo	Triglycerides, total cholesterol and LDL fell; HDL did not change. Triglycerides -26.27 mg/dL; total cholesterol -13.93; LDL -6.13; HDL +0.64 (not significant) (Triglycerides -38.93 to -13.61; LDL -10.72 to -1.53) Methods, limits and funding Outcomes: Lipid profile Limitations: Only the abstract was read. Effects larger in Eastern than Western countries. Read: abstract
Jamali 2020 Effect of cinnamon supplementation on blood pressure and anthropometric parameters in patients with type 2 diabetes: A systematic review and meta-analysis of clinical trials. Diabetes & metabolic syndrome · PMID 32032898 · DOI	Meta-analysis	Adults with type 2 diabetes; 9 articles	Cinnamon supplements bark (as reported) Not given in abstract Varied · vs Placebo	Systolic and diastolic pressure fell; weight, BMI, waist did not change significantly. Systolic SMD -0.532; diastolic SMD -0.681 (Systolic -1.032 to -0.033; diastolic -1.297 to -0.065) Methods, limits and funding Outcomes: Blood pressure, weight, BMI, waist Limitations: Only the abstract was read. Funding and conflicts: Authors declare no conflict Read: abstract
Johnson-Arbor 2021 Stoned on spices: a mini-review of three commonly abused household spices. Clinical toxicology (Philadelphia, Pa.) · PMID 33191804 · DOI	Review	Mini-review of misuse of nutmeg, cinnamon and vanilla	Ground cinnamon and cinnamon oil bark; oil	Cinnamon oils can irritate and cause dermatitis or ulcers on skin; inhaled ground cinnamon contains cellulose fibres that persist in the lungs and can cause chronic lung inflammation and fibrosis. Misuse usually causes mild to moderate symptoms, though some cases need hospital care. Not applicable Methods, limits and funding Outcomes: Harm from misuse Limitations: Only the abstract was read. Read: abstract
Kalogirou 2026 Cinnamon-Induced Contact Stomatitis: A Retrospective Study of 74 Cases and Literature Review. Oral diseases · PMID 40914980 · DOI	Case series	74 74 patients diagnosed 2010 to 2025 with mouth lesions after cinnamon gum or candy	Cinnamon-flavoured chewing gum or sweets flavouring	Lesions on the cheek lining and tongue (white, red or ulcerated); all healed within a week of stopping the product. All 74 resolved within a week of stopping Methods, limits and funding Outcomes: Mouth lesions Limitations: Only the abstract was read. Retrospective series from one group; no estimate of how common it is. Read: abstract
Keramati 2022 Cinnamon, an effective anti-obesity agent: Evidence from an umbrella meta-analysis. Journal of food biochemistry · PMID 35365881 · DOI	Meta-analysis	Adults; umbrella analysis of 7 meta-analyses	Cinnamon supplements bark (as reported) Larger effects at 3 g a day or more reported Varied · vs Control	Small reductions in weight and BMI; waist not significant. Weight -0.67 kg; BMI -0.45 kg/m2; waist -1.05 cm (not significant) (Weight -0.99 to -0.35; BMI -0.57 to -0.33) Methods, limits and funding Outcomes: Body weight, BMI, waist Limitations: Only the abstract was read. Umbrella analyses reuse overlapping trials. The title calls cinnamon an effective anti-obesity agent, which the size of the change does not support. Read: abstract
Khan 2003 Cinnamon improves glucose and lipids of people with type 2 diabetes. Diabetes care · PMID 14633804 · DOI	Controlled trial	60 Adults with type 2 diabetes in Pakistan	Cinnamon (species not stated in abstract) bark 1, 3 or 6 g a day 40 days then 20-day washout · vs Placebo capsules	Fasting glucose, triglycerides, LDL and total cholesterol fell in all three cinnamon groups; HDL did not change. Fasting glucose -18 to -29%; triglycerides -23 to -30%; LDL -7 to -27%; total cholesterol -12 to -26% Methods, limits and funding Outcomes: Fasting glucose, triglycerides, cholesterol Limitations: Only the abstract was read. This often-cited 2003 trial now carries an Expression of Concern from the journal (Diabetes Care, 2025), meaning its reliability is under question. We cite it only to show where early positive results came from, and rely on it for nothing. It is not a retraction. Read: abstract
Krittanawong 2022 Association Between Cinnamon Consumption and Risk of Cardiovascular Health: A Systematic Review and Meta-Analysis. The American journal of medicine · PMID 34411521 · DOI	Meta-analysis	1070 23 studies, adults; authors call the included studies heterogeneous and generally of very poor quality	Cinnamon consumption bark (as reported) Not given in abstract Not given in abstract · vs No cinnamon / placebo	No difference in LDL, HDL or HbA1c between cinnamon and comparison groups. LDL WMD 0.38; HDL WMD 0.40; HbA1c WMD 0.0 (LDL -6.07 to 6.83; HDL -1.14 to 1.94; HbA1c -0.44 to 0.45) Methods, limits and funding Outcomes: HbA1c, LDL, HDL Limitations: Only the abstract was read. This is the main null pooled result. It used a different outcome set from most reviews and judged the trials very poor quality. Read: abstract
Leach 2012 Cinnamon for diabetes mellitus. The Cochrane database of systematic reviews · PMID 22972104 · DOI	Systematic review	577 People with type 1 or type 2 diabetes; 10 randomized trials	Oral cinnamon alone (mostly Cinnamomum cassia) bark Mean 2 g a day 4 to 16 weeks · vs Placebo, active drug or no treatment	Fasting glucose result was inconclusive. No significant difference in HbA1c, insulin or after-meal glucose. No data on quality of life, illness or death. Reactions were infrequent and mild. No significant HbA1c difference; fasting glucose inconclusive Methods, limits and funding Outcomes: Fasting glucose, HbA1c, insulin, after-meal glucose, quality of life, complications Limitations: Only the abstract was read. Searched to January 2012, so newer trials are missing. Risk of bias was high or unclear in all but two trials. Authors concluded the evidence was insufficient. Funding and conflicts: Authors state no known conflict of interest Read: abstract
Li 2021 Cinnamomum cassia extract promotes thermogenesis during exposure to cold via activation of brown adipose tissue. Journal of ethnopharmacology · PMID 32980484 · DOI	Animal experiment animal	Animals exposed to cold, plus brown fat cells in culture	Cinnamomum cassia extract bark (extract) Not given in abstract Not given in abstract · vs Untreated	The extract raised body temperature and energy use in cold conditions and uncoupled mitochondria in brown fat cells. Not quantified in the abstract Methods, limits and funding Outcomes: Body temperature, energy use, brown fat markers Limitations: Only the abstract was read (the abstract was truncated in our copy). Animal and cell work; no human data. Read: abstract
Lira Neto 2022 Efficacy of Cinnamon as an Adjuvant in Reducing the Glycemic Biomarkers of Type 2 Diabetes Mellitus: A Three-Month, Randomized, Triple-Blind, Placebo-Controlled Clinical Trial. Journal of the American Nutrition Association · PMID 33605836 · DOI	Controlled trial	160 Adults with type 2 diabetes on oral diabetes drugs, HbA1c 6.0% or more, in Brazil	Cinnamon capsules (species not stated in abstract) 3 g a day 90 days · vs Placebo capsules	Small reductions in HbA1c and fasting glucose compared with placebo, added to usual diabetes drugs. HbA1c -0.2 percentage points; fasting glucose -0.55 mmol/L vs placebo Methods, limits and funding Outcomes: HbA1c (main), fasting glucose, insulin, HOMA-IR Limitations: Only the abstract was read. Authors call the reductions modest. Registered RBR-2KKB6D. Funding and conflicts: Not stated in abstract Read: abstract
Lu 2012 Cinnamon extract improves fasting blood glucose and glycosylated hemoglobin level in Chinese patients with type 2 diabetes. Nutrition research (New York, N.Y.) · PMID 22749176 · DOI	Controlled trial	66 Chinese adults with type 2 diabetes, all taking gliclazide	Cinnamon extract bark (extract) 120 mg or 360 mg a day 3 months · vs Placebo	HbA1c and fasting glucose fell in both extract groups and not in placebo; triglycerides fell in the low-dose group; cholesterol and liver enzymes did not change. Directions reported; values not in abstract Methods, limits and funding Outcomes: HbA1c and fasting glucose, lipids, liver enzymes Limitations: Only the abstract was read. Small. Within-group changes emphasised in the abstract. Read: abstract
Lungarini 2008 Coumarin and cinnamaldehyde in cinnamon marketed in Italy: a natural chemical hazard? Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment · PMID 19680836 · DOI	Laboratory survey n/a	84 34 cinnamon samples and 50 cinnamon-containing foods bought in Italy	Cinnamon products bark	About 51% of cinnamon samples were cassia, 10% blends and only 39% Ceylon cinnamon. Many cinnamon foods exceeded the then EU limit of 2 mg/kg. 51% cassia, 10% blend, 39% Ceylon Methods, limits and funding Outcomes: Coumarin and cinnamaldehyde by HPLC Limitations: Only the abstract was read. Italian market in the 2000s; labelling may have changed. Read: abstract
Maierean 2017 The effects of cinnamon supplementation on blood lipid concentrations: A systematic review and meta-analysis. Journal of clinical lipidology · PMID 28887086 · DOI	Meta-analysis	750 Adults; 13 randomized trials	Cinnamon supplements bark (as reported) Not given in abstract (dose not linked to effect) Varied · vs Placebo	Triglycerides and total cholesterol fell; LDL and HDL did not change significantly (HDL rose when one trial was left out). Triglycerides -23.91 mg/dL; total cholesterol -13.92 mg/dL; LDL -6.19 mg/dL (not significant); HDL +1.92 (not significant) (Triglycerides -34.54 to -12.40; total cholesterol -24.36 to -3.48; LDL -13.53 to 1.16) Methods, limits and funding Outcomes: LDL, HDL, triglycerides, total cholesterol Limitations: Only the abstract was read. Read: abstract
Majeed 2025 Safety and effectiveness of marjoram and cinnamon herbal tea supplementation in managing polycystic ovary syndrome: a pilot randomized, double-blind, controlled trial. Annals of medicine and surgery (2012) · PMID 41377384 · DOI	Controlled trial	60 Women with PCOS; only 36 finished	Marjoram plus cinnamon herbal tea (combination) Twice a day 3 months · vs Placebo tea	No major side effects. Hormone changes appeared in both groups (AMH fell in both); FSH rose in the herbal tea group. Mixed within-group changes Methods, limits and funding Outcomes: Hormones and lipids, safety Limitations: Only the abstract was read. A combination tea, so effects cannot be credited to cinnamon. Pilot, large dropout. Funding and conflicts: Authors declare no conflict Read: abstract
Mansour 2025 The efficacy and safety of berberine in combination with cinnamon supplementation in patients with type 2 diabetes: a randomized clinical trial. European journal of nutrition · PMID 39998703 · DOI	Controlled trial	Adults with type 2 diabetes	Berberine plus cinnamon, combined 1,200 mg berberine and 600 mg cinnamon a day 12 weeks · vs Placebo	Fasting sugar, HbA1c and LDL were lower with the combination; other measures were not different. p values only (fasting sugar 0.031; HbA1c 0.013; LDL 0.039) Methods, limits and funding Outcomes: Fasting sugar, HbA1c, lipids, blood pressure Limitations: Only the abstract was read. A combination product: berberine is itself a glucose-lowering compound, so no effect can be credited to cinnamon. Funding and conflicts: One author is an employee of the company that made the supplement (declared) Read: abstract
Momtaz 2018 Cinnamon, a promising prospect towards Alzheimer's disease. Pharmacological research · PMID 29258915 · DOI	Narrative review in-vitro	Cinnamon and Alzheimer disease (laboratory and animal studies)	Cinnamon extracts and compounds bark	Authors report that cinnamon extract blocks tau and amyloid-beta clumping in animal and test-tube models and call for clinical trials. Not applicable Methods, limits and funding Outcomes: Tau and amyloid-beta in models Limitations: Only the abstract was read. No human trial is reported in the abstract. Read: abstract
Moridpour 2024 The effect of cinnamon supplementation on glycemic control in patients with type 2 diabetes mellitus: An updated systematic review and dose-response meta-analysis of randomized controlled trials. Phytotherapy research : PTR · PMID 37818728 · DOI	Meta-analysis	Adults with type 2 diabetes; 24 randomized trials	Cinnamon supplements (forms and species varied) bark (as reported; species mixed) Dose-response analysed; doses not given in abstract Not given in abstract · vs Placebo or control	Fasting sugar, insulin resistance and HbA1c were lower with cinnamon; fasting insulin did not change significantly. Fasting blood sugar SMD -1.32; HOMA-IR SMD -1.32 (identical figures in the abstract); HbA1c SMD -0.67; insulin SMD -0.17 (not significant) (Fasting sugar -1.77 to -0.87; HbA1c -1.18 to -0.15; insulin -0.34 to 0.01) Methods, limits and funding Outcomes: Fasting blood sugar, HOMA-IR, HbA1c, insulin Limitations: Only the abstract was read. Standardised units (not mg/dL), so hard to translate into daily-life size. The abstract gives identical numbers for fasting sugar and HOMA-IR, which looks like a copying slip we cannot check. Certainty rating not stated in the abstract. Searched to December 2022. Read: abstract
Mousavi 2021 What is the influence of cinnamon supplementation on liver enzymes? A systematic review and meta-analysis of randomized controlled trials. Phytotherapy research : PTR · PMID 34212447 · DOI	Meta-analysis	256 Adults; 7 trials (9 arms)	Cinnamon supplements bark (as reported) Under 1,500 mg a day subgroup noted Varied · vs Control	No significant change in ALT, AST or ALP overall; ALT and AST lower in people with type 2 diabetes in longer trials. ALT in type 2 diabetes -4.01 U/L (-6.86 to -1.15) Methods, limits and funding Outcomes: ALT, AST, ALP (liver enzymes) Limitations: Only the abstract was read. Only 256 people, mostly with normal enzymes. Authors say trials in people with abnormal liver tests are needed. A lack of enzyme rise in short trials does not rule out rare liver injury. Read: abstract
Muthukuda 2025 Effects of Cinnamomum zeylanicum (Ceylon cinnamon) extract on lipid profile, glucose levels and its safety in adults: A randomized, double-blind, controlled trial. PloS one · PMID 39854533 · DOI	Controlled trial	150 Adults in Sri Lanka with LDL between 100 and 190 mg/dL (66% women); 127 assessed at 12 weeks	Standardised Cinnamomum zeylanicum (Ceylon) extract capsules bark (extract) 1,000 mg a day 12 weeks · vs Placebo	LDL cholesterol did not fall significantly. Fasting glucose fell more on cinnamon, especially in people with type 2 diabetes. LDL adjusted difference 6.05 mg/dL (not significant); fasting glucose adjusted difference 8.59 mg/dL (LDL -2.43 to 14.52; fasting glucose 0.59 to 16.59) Methods, limits and funding Outcomes: LDL cholesterol (main); other lipids, fasting glucose, blood pressure, safety Limitations: Only the abstract was read. Main (LDL) result was null; glucose was secondary. The fasting-glucose subgroup finding in diabetes comes from an interaction analysis. Funding and conflicts: Funded by SDS Spices Pvt Ltd (spice company), which also paid for two authors' time; authors say funding did not influence the study Read: abstract
Namazi 2019 The impact of cinnamon on anthropometric indices and glycemic status in patients with type 2 diabetes: A systematic review and meta-analysis of clinical trials. Complementary therapies in medicine · PMID 30935562 · DOI	Meta-analysis	Adults with type 2 diabetes; 18 randomized trials	Cinnamon supplements bark (as reported) Not given in abstract Not given in abstract · vs Placebo	Fasting glucose fell; HbA1c fell slightly; weight, BMI and waist did not change significantly. Fasting glucose -19.26 mg/dL; HbA1c -0.24%; weight, BMI, waist not significant (Fasting glucose -28.08 to -10.45 (I2 96.5%); HbA1c -0.48 to -0.01 (I2 76.8%)) Methods, limits and funding Outcomes: Fasting sugar, HbA1c, weight, BMI, waist Limitations: Only the abstract was read. Authors advise great caution because of the high heterogeneity. Searched to early 2018. Read: abstract
Neto 2019 Maternal cinnamon intake during lactation led to visceral obesity and hepatic metabolic dysfunction in the adult male offspring. Endocrine · PMID 30276593 · DOI	Animal experiment animal	Rat mothers fed cinnamon during nursing and their adult male offspring	Cinnamon aqueous extract bark (extract) 400 mg/kg/day to the mothers Whole nursing period · vs Untreated mothers	The offspring grew up with more belly fat, high insulin and leptin, and a mildly fatty liver. Reported p values 0.001 to 0.05 Methods, limits and funding Outcomes: Offspring weight, insulin and liver changes Limitations: Only the abstract was read. Rats given a large extract dose; not proof of harm in people but a reason for caution in nursing. Read: abstract
Not listed in PubMed record (database entry) 2006 Cinnamon. · PMID 40986675	Database entry n/a	LactMed entry on cinnamon (NICHD), updated October 2026	Cinnamon (Ceylon) bark	Entry says no data exist on the safety of cinnamon in nursing mothers or infants, and that cassia has high amounts of coumarin; no studies of milk supply were found. Not applicable Methods, limits and funding Outcomes: Use during breastfeeding Limitations: Only the PubMed summary of the entry was read. Read: abstract
Park 2023 Cinnamon (Cinnamomum cassia) water extract improves diarrhea symptoms by changing the gut environment: a randomized controlled trial. Food & function · PMID 36655542 · DOI	Controlled trial	70 Adults with diarrhoea symptoms	Cinnamomum cassia water extract capsules bark (water extract) 3 capsules of 400 mg twice a day 8 weeks · vs Placebo	Slower colonic transit time and changes in stool chemicals and gut bacteria; authors say diarrhoea symptoms improved. Colonic transit time p 0.019 Methods, limits and funding Outcomes: Bowel transit, stool chemistry, gut bacteria Limitations: Only the abstract was read. The abstract does not give a symptom score. A water extract of cassia, which may differ in coumarin from the bark powder. Read: abstract
Pattanittum 2016 Dietary supplements for dysmenorrhoea. The Cochrane database of systematic reviews · PMID 27000311 · DOI	Systematic review	Women with painful periods; Cochrane review of dietary supplement trials	Many supplements including Cinnamomum zeylanicum (C. verum) bark Not given in abstract Not given in abstract · vs Placebo, NSAIDs or others	For chamomile and cinnamon versus placebo the data were unsuitable for analysis, so no conclusion on cinnamon could be drawn. Not analysable for cinnamon Methods, limits and funding Outcomes: Pain relief Limitations: Only the abstract was read. Only the cinnamon statement is used here. Read: abstract
Peivandi 2024 Metabolic and endocrine changes induced by cinnamon in women with polycystic ovarian syndrome: A pilot study. Avicenna journal of phytomedicine · PMID 38966626 · DOI	Controlled trial	39 Overweight or obese women with PCOS	Cinnamon capsules 1,500 mg a day (three 500 mg capsules) 6 months · vs Placebo	Ovarian volume and abdominal fat differed between groups; BMI, lipids, insulin resistance and androgens did not. Differences in ovarian volume and subcutaneous fat; others not significant Methods, limits and funding Outcomes: Ovarian volume, androgens, metabolic measures Limitations: Only the abstract was read. Pilot study, 39 women. Funding and conflicts: Authors declare no conflict Read: abstract
Permadi 2021 Administration of Cinnamon and Lagersroemia speciosa Extract on Lipid Profile of Polycystic Ovarian Syndrome Women with High Body Mass Index. Journal of human reproductive sciences · PMID 34083987 · DOI	Non randomized trial	62 Women with PCOS, insulin resistance	DLBS3233, a combination of Cinnamomum burmanni and Lagerstroemia speciosa extracts bark (extract) plus leaf of another plant 100 mg a day 3 and 6 months · vs No control group	Triglycerides, HOMA-IR and free testosterone fell in women with BMI 25 or more. Reported as improvements; numbers not in abstract Methods, limits and funding Outcomes: Lipids, HOMA-IR, free testosterone Limitations: Only the abstract was read. No control group and a branded combination with another plant, so it says little about cinnamon. Funding and conflicts: Authors declare no conflict Read: abstract
Rachid 2022 Effect of Aqueous Cinnamon Extract on the Postprandial Glycemia Levels in Patients with Type 2 Diabetes Mellitus: A Randomized Controlled Trial. Nutrients · PMID 35458138 · DOI	Controlled trial	36 Adults with type 2 diabetes	Aqueous (water) cinnamon extract bark (extract) 6 g in 100 mL after a glucose drink Single test · vs Glucose drink alone (no placebo)	No difference in glucose area under the curve, peak or variation. p 0.834 for area under the curve Methods, limits and funding Outcomes: After-meal glucose Limitations: Only the abstract was read. No placebo drink. Funding and conflicts: Authors declare no conflict Read: abstract
Rana 2023 Discrimination of four Cinnamomum species by proximate, antioxidant, and chemical profiling: towards quality assessment and authenticity. Journal of food science and technology · PMID 37599847 · DOI	Laboratory survey n/a	Four Cinnamomum species compared by chemistry	C. verum, C. burmannii, C. cassia, C. loureiroi bark	C. verum had the lowest coumarin (1.90%) and highest eugenol (5.77%) in the GC-MS profile; the authors say cheaper, hepatotoxic species are used to adulterate it. Coumarin 1.90% in C. verum (lowest of four); percentages as reported, not mg/kg Methods, limits and funding Outcomes: Coumarin, eugenol, antioxidants Limitations: Only the abstract was read. Percent of the GC-MS profile, not mg per kg of bark. Funding and conflicts: Authors declare no conflict Read: abstract
Ranasinghe 2012 Efficacy and safety of 'true' cinnamon (Cinnamomum zeylanicum) as a pharmaceutical agent in diabetes: a systematic review and meta-analysis. Diabetic medicine : a journal of the British Diabetic Association · PMID 22671971 · DOI	Systematic review animal	16 non-human studies of Ceylon cinnamon (5 test-tube, 6 animal, 5 mixed)	Cinnamomum zeylanicum (true cinnamon) extracts bark	Found no human studies of Ceylon cinnamon at the time. Test-tube and animal work pointed to effects on starch-digesting enzymes and glucose uptake, with no significant toxic effects on liver and kidney in animals. Not applicable (no human data) Methods, limits and funding Outcomes: Effects on glucose handling and safety Limitations: Only the abstract was read. Searched in 2012; human trials of Ceylon cinnamon have appeared since. Animal results do not show what happens in people. Read: abstract
Ranasinghe 2025 Efficacy and Safety of Cinnamomum zeylanicum (Ceylon cinnamon) for diabetes mellitus: a randomized, double blind, placebo-controlled clinical trial. Diabetes & metabolic syndrome · PMID 41412108 · DOI	Controlled trial	210 Adults with type 2 diabetes in Sri Lanka (mean age 58.6); 186 finished	Standardised Cinnamomum zeylanicum (Ceylon) extract bark (extract) 250 mg or 500 mg (two arms) 4 months · vs Placebo	Fasting glucose and HbA1c fell from baseline in both extract groups, with lower insulin resistance and better beta-cell function; total and LDL cholesterol lower in the 500 mg group. Abstract gives p values (<0.05) rather than the size of the changes; change from baseline stressed Methods, limits and funding Outcomes: HbA1c and fasting plasma glucose; secondary lipids, insulin resistance, blood pressure Limitations: Only the abstract was read. The abstract compares with baseline and uses regression, and gives no between-group differences in numbers. Registered SLCTR/2017/010. All authors hold a Sri Lankan patent, so there is a commercial interest. Funding and conflicts: All authors hold a patent issued by the National Intellectual Property Office, Sri Lanka (declared) Read: abstract
Sarmadi 2023 The effect of cinnamon consumption on lipid profile, oxidative stress, and inflammation biomarkers in adults: An umbrella meta-analysis of randomized controlled trials. Nutrition, metabolism, and cardiovascular diseases : NMCD · PMID 37500345 · DOI	Meta-analysis	Adults; umbrella analysis of 11 meta-analyses	Cinnamon bark (as reported) Not given in abstract Varied · vs Placebo	Small improvements in total cholesterol, LDL and HDL; no significant effect on triglycerides, MDA or CRP. Total cholesterol -1.01 mg/dL; LDL -0.82; HDL +0.47; triglycerides -0.13 (not significant) (Total cholesterol -2.02 to 0.00; LDL -1.57 to -0.07; HDL 0.17 to 0.77) Methods, limits and funding Outcomes: Lipids, oxidative stress and inflammation markers Limitations: Only the abstract was read. The effect sizes are very small. The abstract text about IL-6 is internally inconsistent, so we do not use it. Funding and conflicts: Authors declare no conflict Read: abstract
Soares APDC 2022 Cinnamon Infusion Reduces Satiety and Increases Energy Intake: A Randomized Crossover Trial. Annals of nutrition & metabolism · PMID 35830848 · DOI	Controlled trial	21 Healthy adults (crossover)	Cinnamon infusion (Cinnamomum sp.) bark (infusion) 2 g in a drink (single dose) Single test · vs Water	No change in energy use; less feeling of fullness and slightly more food eaten at the next meal. Satiety lower (p 0.021); next-meal energy higher (p 0.05) Methods, limits and funding Outcomes: Energy use, appetite, food intake Limitations: Only the abstract was read. Open-label. Read: abstract
Sproll 2008 HPLC analysis and safety assessment of coumarin in foods. Food chemistry · PMID 26003373 · DOI	Laboratory survey n/a	Cinnamon-flavoured foods in Germany	Cinnamon-flavoured foods bark	Bakery products and cereals averaged 9 mg/kg coumarin; some cookies up to 88 mg/kg. Up to 88 mg/kg in some cookies Methods, limits and funding Outcomes: Coumarin by HPLC Limitations: Only the abstract was read. Read: abstract
Talaei 2017 Effects of Cinnamon Consumption on Glycemic Indicators, Advanced Glycation End Products, and Antioxidant Status in Type 2 Diabetic Patients. Nutrients · PMID 28885566 · DOI	Controlled trial	44 Adults with type 2 diabetes in Iran; 39 finished	Cinnamon supplement 3 g a day 8 weeks · vs Placebo	No significant change in any measure, within or between groups. No significant differences Methods, limits and funding Outcomes: Fasting glucose, insulin, HbA1c, HOMA-IR, glycation and antioxidant markers Limitations: Only the abstract was read. Funding and conflicts: Authors declare no conflict Read: abstract
Vallianou 2019 Effect of cinnamon (Cinnamomum Zeylanicum) supplementation on serum C-reactive protein concentrations: A meta-analysis and systematic review. Complementary therapies in medicine · PMID 30670254 · DOI	Meta-analysis	285 Adults; 6 trials of Cinnamomum zeylanicum as named in the title	Cinnamon supplements bark (as reported) Under and over 1,500 mg a day compared Varied · vs Control	CRP fell, more so when starting CRP was high and trials were longer than 12 weeks. CRP -0.81 mg/L (-1.36 to -0.26) Methods, limits and funding Outcomes: C-reactive protein (CRP) Limitations: Only the abstract was read. Significant heterogeneity. The title names Ceylon cinnamon but the abstract does not state the species used in each trial. Read: abstract
Vasconcelos 2018 Antibacterial mechanisms of cinnamon and its constituents: A review. Microbial pathogenesis · PMID 29702210 · DOI	Narrative review in-vitro	How cinnamon and its compounds act on bacteria	Cinnamon and constituents bark	Review of lab mechanisms of antibacterial action. Not applicable Methods, limits and funding Outcomes: Antibacterial mechanisms Limitations: Only the abstract was read. Lab work. Read: abstract
Wainstein 2011 Dietary cinnamon supplementation and changes in systolic blood pressure in subjects with type 2 diabetes. Journal of medicinal food · PMID 21861719 · DOI	Controlled trial	59 Adults with type 2 diabetes	Cinnamon 1,200 mg a day 12 weeks · vs Placebo	Systolic pressure fell 3.4 mmHg on cinnamon and rose 1.9 on placebo (p 0.06); after adjusting for starting pressure the difference vanished. Authors attribute it to regression to the mean. Systolic -3.4 vs +1.9 mmHg (p 0.06) Methods, limits and funding Outcomes: Blood pressure (main), HbA1c, glucose, lipids Limitations: Only the abstract was read. Read: abstract
Wickenberg 2012 Ceylon cinnamon does not affect postprandial plasma glucose or insulin in subjects with impaired glucose tolerance. The British journal of nutrition · PMID 21929834 · DOI	Controlled trial	10 Adults with impaired glucose tolerance (crossover)	Cinnamomum zeylanicum (Ceylon) capsules bark 6 g with a 75 g glucose drink (single dose) Single test · vs Placebo capsules	No effect on glucose or insulin after the glucose drink. No significant difference Methods, limits and funding Outcomes: After-meal glucose and insulin, glycaemic index Limitations: Only the abstract was read. Ten people, one dose. Read: abstract
Wickenberg 2014 Cassia cinnamon does not change the insulin sensitivity or the liver enzymes in subjects with impaired glucose tolerance. Nutrition journal · PMID 25249415 · DOI	Controlled trial	21 Adults with impaired glucose tolerance; 17 finished	Cinnamomum cassia capsules bark 6 g twice a day (12 g a day) 12 weeks · vs Placebo	No change in insulin sensitivity, HbA1c, fasting glucose, BMI, lipids or liver enzymes. No significant effects Methods, limits and funding Outcomes: Insulin sensitivity by clamp, HbA1c, fasting glucose, lipids, liver enzymes Limitations: Only the abstract was read. Very small. The dose was high, yet liver enzymes did not change over 12 weeks in these 9 treated people. Read: abstract
Wu 2022 Effects of cinnamon supplementation on lipid profiles among patients with metabolic syndrome and related disorders: A systematic review and meta-analysis. Complementary therapies in clinical practice · PMID 35803022 · DOI	Meta-analysis	773 Adults with metabolic syndrome and related disorders; 12 studies	Cinnamon or extracts bark (as reported) High dose (1.5 g a day or more) compared Varied · vs Placebo	Total cholesterol, triglycerides and LDL fell. No significant lipid effect in European and American patients. Total cholesterol -7.34 mg/dL; triglycerides -8.85; LDL -6.18 (Total cholesterol -9.27 to -5.41; triglycerides -14.16 to -3.54; LDL -7.72 to -4.25) Methods, limits and funding Outcomes: Lipid profile Limitations: Only the abstract was read. Funding and conflicts: Authors declare no conflict Read: abstract
Xiaomei 2024 Effect of cinnamon as a Chinese herbal medicine on markers of cardiovascular risk in women with polycystic ovary syndrome: A systematic review and meta-analysis of randomized controlled trials. European journal of obstetrics, gynecology, and reproductive biology · PMID 39053085 · DOI	Meta-analysis	Women with PCOS; 12 randomized trials	Cinnamon supplements bark (as reported) Not given in abstract Varied · vs Placebo	Small reductions in weight, fasting sugar, total cholesterol and LDL; reduced HOMA-IR. Weight -0.47 kg; fasting sugar -7.72 mg/dL; total cholesterol -11.12; LDL -11.11 (Weight -0.80 to -0.15; fasting sugar -12.33 to -3.12 (I2 91%)) Methods, limits and funding Outcomes: Weight, HOMA-IR, fasting sugar, lipids Limitations: Only the abstract was read. The abstract gives the HOMA-IR figure as a positive number (0.5015) while describing a reduction, so the direction is as stated in words only. Funding and conflicts: Authors declare no conflict Read: abstract
Xu 2020 Efficacy of herbal medicine (cinnamon/fennel/ginger) for primary dysmenorrhea: a systematic review and meta-analysis of randomized controlled trials. The Journal of international medical research · PMID 32603204 · DOI	Meta-analysis	647 Women with primary period pain; 9 studies (cinnamon, fennel, ginger)	Cinnamon, fennel or ginger bark (as reported) Not given in abstract One cycle in most · vs Placebo	Pain intensity lower with each herb; pain duration shorter with cinnamon. Cinnamon vs placebo pain WMD 1.815; pain duration WMD 16.200 (Pain 1.330 to 2.301) Methods, limits and funding Outcomes: Pain intensity and duration Limitations: Only the abstract was read. The reported intervals and the direction of the numbers are hard to interpret from the abstract; few cinnamon trials; authors ask for more studies. Read: abstract
Yanakiev 2020 Effects of Cinnamon (Cinnamomum spp.) in Dentistry: A Review. Molecules (Basel, Switzerland) · PMID 32932678 · DOI	Narrative review in-vitro	Cinnamon in dentistry (lab and clinical literature)	Cinnamon oil, extracts, compounds bark	Authors say cinnamon oil, extracts and compounds show significant antimicrobial effects against mouth pathogens. Not applicable Methods, limits and funding Outcomes: Antimicrobial effects against mouth organisms Limitations: Only the abstract was read. Mostly lab work. Read: abstract
Yazdanpanah 2020 Effects of cinnamon supplementation on body weight and composition in adults: A systematic review and meta-analysis of controlled clinical trials. Phytotherapy research : PTR · PMID 31800140 · DOI	Meta-analysis	1480 Adults; 21 randomized trials	Cinnamon supplements bark (as reported) Not given in abstract Varied · vs Control	Small reductions in weight, BMI and waist-hip ratio; waist and fat mass not significant. Weight -0.92 kg; BMI -0.40 kg/m2; waist-hip ratio -0.02; waist -1.76 cm (not significant) (Weight -1.51 to -0.33 (I2 84%); BMI -0.57 to -0.22) Methods, limits and funding Outcomes: Body weight, BMI, waist, waist-hip ratio, fat mass Limitations: Only the abstract was read. Under 1 kg average loss; high heterogeneity. Read: abstract
Yesukumar 2025 Probable Cinnamon-Induced Mixed Hepatocellular-Cholestatic Liver Injury in a Young Woman: A Case Report. Cureus · PMID 41158894 · DOI	Case report	1 34-year-old woman	Cinnamon taken for weight loss for a prolonged time (species and amount not stated) Prolonged	Abdominal pain, jaundice, dark urine and a mixed liver-cholestatic injury pattern; full recovery after stopping. Recovery after stopping Methods, limits and funding Outcomes: Liver tests Limitations: Only the abstract was read. One case. Authors describe it as probable, not proven. Funding and conflicts: No financial relationships declared Read: abstract
Zare 2019 Efficacy of cinnamon in patients with type II diabetes mellitus: A randomized controlled clinical trial. Clinical nutrition (Edinburgh, Scotland) · PMID 29605574 · DOI	Controlled trial	140 Adults with type 2 diabetes in Iran, split by BMI 27 or more vs under 27	Cinnamon bark powder capsules (species not stated in abstract) bark powder 500 mg twice a day 3 months · vs Placebo capsules	Improvements in weight measures, fasting glucose, 2-hour glucose, HbA1c, insulin resistance, total and LDL cholesterol; triglycerides did not change. Larger in people with BMI 27 or more. Direction of change reported; numbers not in abstract Methods, limits and funding Outcomes: Body measures, glucose, HbA1c, insulin resistance, lipids Limitations: Only the abstract was read. Species not named. Registered IRCT2017031133015N1. Read: abstract
Zarezadeh 2023 The effect of cinnamon supplementation on glycemic control in patients with type 2 diabetes or with polycystic ovary syndrome: an umbrella meta-analysis on interventional meta-analyses. Diabetology & metabolic syndrome · PMID 37316893 · DOI	Meta-analysis	Adults with type 2 diabetes or PCOS; umbrella analysis of 11 earlier meta-analyses	Cinnamon supplements bark (as reported) Not given in abstract Not given in abstract · vs Placebo	Pooling earlier meta-analyses gave lower fasting glucose, insulin, HOMA-IR and a small HbA1c drop. Fasting glucose -10.93 mg/dL; insulin -2.01 IU/mL; HOMA-IR -0.61; HbA1c -0.10% (Fasting glucose -16.22 to -5.65; HbA1c -0.17 to -0.03) Methods, limits and funding Outcomes: Fasting glucose, insulin, HOMA-IR, HbA1c Limitations: Only the abstract was read. An umbrella analysis reuses overlapping trials, so it is not independent confirmation. Searched to June 2022. Funding and conflicts: Authors declare no conflicts Read: abstract
Zelicha 2024 Effect of cinnamon spice on continuously monitored glycemic response in adults with prediabetes: a 4-week randomized controlled crossover trial. The American journal of clinical nutrition · PMID 38290699 · DOI	Controlled trial	18 Adults with obesity and prediabetes (mean fasting glucose 102.9 mg/dL), crossover	Cinnamon spice (species not stated in abstract) bark (ground spice) 4 g a day 4 weeks per arm, 2-week washout · vs Placebo	24-hour glucose and glucose peaks were lower on cinnamon; triglycerides lower; no difference in digestive symptoms. Peak rise 9.56 vs 11.73 mg/dL (p 0.027); 24-hour glucose lower (p<0.001) (Peak difference 0.8 to 3.7) Methods, limits and funding Outcomes: 24-hour glucose on continuous monitor, glucose peaks, digestive symptoms Limitations: Only the abstract was read. Only 18 people. Registered NCT04342624. Funding not in abstract. Read: abstract
Zhu 2017 Cinnamaldehyde in diabetes: A review of pharmacology, pharmacokinetics and safety. Pharmacological research · PMID 28559210 · DOI	Narrative review animal	Cinnamaldehyde in diabetes (animal and lab studies)	Cinnamaldehyde bark compound	Cinnamaldehyde improved glucose and fat handling in diabetic animals through several pathways; it is converted in the body to cinnamyl alcohol, methyl cinnamate and cinnamic acid; authors note a potential toxicity concern and call for clinical trials. Not applicable Methods, limits and funding Outcomes: Pharmacology, pharmacokinetics, safety Limitations: Only the abstract was read. Read: abstract
Zhu 2020 Impact of Cinnamon Supplementation on cardiometabolic Biomarkers of Inflammation and Oxidative Stress: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Complementary therapies in medicine · PMID 33066854 · DOI	Meta-analysis	Adults; 12 randomized trials	Cinnamon powder (1.5 to 4 g a day) bark powder 1.5 to 4 g a day Varied · vs Control	CRP and MDA fell, total antioxidant capacity rose, IL-6 fell marginally, ICAM-1 did not change. CRP -2.22 mg/L; MDA -0.79 mmol/L; IL-6 -1.48 pg/mL (p 0.049); TAC +0.34 mmol/L (CRP -3.74 to -0.69; IL-6 -2.96 to -0.01) Methods, limits and funding Outcomes: CRP, MDA, IL-6, total antioxidant capacity, ICAM-1 Limitations: Only the abstract was read. Read: abstract
de Araújo 2021 Efficacy of essential oil of cinnamon for the treatment of oral candidiasis: A randomized trial. Special care in dentistry : official publication of the American Association of Hospital Dentists, the Academy of Dentistry for the Handicapped, and the American Society for Geriatric Dentistry · PMID 33475184 · DOI	Controlled trial	36 People with oral thrush (candidiasis)	Cinnamomum zeylanicum essential oil mouthwash and spray bark oil 0.5 mg/mL 15 days · vs Nystatin (antifungal drug)	Both improved signs; cinnamon reduced Candida counts by 61% on mucosa and 33% on dentures. Clinical efficacy p 0.0339 (cinnamon); Candida -61% mucosa, -33% dentures Methods, limits and funding Outcomes: Clinical signs and Candida counts Limitations: Only the abstract was read. Small; compared with a drug, not with placebo. Read: abstract
de Moura 2025 Effects of cinnamon supplementation on metabolic biomarkers in individuals with type 2 diabetes: a systematic review and meta-analysis. Nutrition reviews · PMID 38917435 · DOI	Meta-analysis	3054 Adults and older adults with type 2 diabetes; 28 randomized trials	Cinnamon supplements, mostly capsules (species mixed) bark (as reported) Up to and above 2 g a day compared 30 to 120 days · vs Placebo or control	Pooled results favoured cinnamon for glucose, HbA1c, insulin resistance; capsule form and 2 g a day or less looked best in subgroups. Very high heterogeneity. Fasting glucose -15.26 mg/dL; after-meal glucose -39.22 mg/dL; HbA1c -0.56 (abstract writes mg/dL; HbA1c is a percentage); HOMA-IR -0.76 (Fasting glucose -22.23 to -8.30 (I2 88%); after-meal -63.90 to -14.55 (I2 100%); HbA1c -0.99 to -0.13 (I2 94%); HOMA-IR -1.13 to -0.39) Methods, limits and funding Outcomes: Fasting and after-meal glucose, HbA1c, HOMA-IR, lipids, BMI Limitations: Only the abstract was read. I2 of 88 to 100 percent means the trials disagree a great deal. The review used GRADE but the abstract does not give the resulting rating. Registered PROSPERO CRD42022370332. Read: abstract
s-bfr-coumarin-faq German Federal Institute for Risk Assessment (BfR): FAQ on coumarin in cinnamon and other foods (27 Sept 2012) · Source	Authoritative guidance n/a			Methods, limits and funding Read: summary-only
s-ema-hmpc-cinnamon-oil EMA/HMPC community herbal monograph on Cinnamomum verum J.S. Presl, cortex and corticis aetheroleum (compiled 10 May 2011) · Source	Authoritative guidance n/a			Methods, limits and funding Read: summary-only
s-gbif-cinnamomum-aromaticum GBIF Backbone Taxonomy: Cinnamomum aromaticum Nees (usageKey 3033982) · Source	Reference database n/a			Methods, limits and funding Read: full-text
s-gbif-cinnamomum-verum GBIF Backbone Taxonomy: Cinnamomum verum J.Presl (usageKey 3033987) · Source	Reference database n/a			Methods, limits and funding Read: full-text
s-ncbi-taxonomy-cinnamomum NCBI Taxonomy: Cinnamomum verum (taxid 128608), Cinnamomum burmannii (119261) and the entry for cassia (taxid 230708) · Source	Reference database n/a			Methods, limits and funding Read: summary-only
s-nccih-cinnamon NCCIH: Cinnamon · Source	Authoritative guidance n/a			Methods, limits and funding Read: summary-only

What we do not know yet

What the evidence supports: nothing is rated moderate or high. Fasting blood sugar and insulin resistance in type 2 diabetes are low; HbA1c, after-meal sugar and cholesterol are mixed.
What is uncertain: pooled trials disagree strongly, are small and short (under about 4 months) and often do not name the cinnamon species, so Ceylon and cassia results are mixed together.
What is unstudied: no trial measured diabetes complications, heart attacks, strokes or deaths; no trial tested cinnamon to prevent diabetes; no human trial exists for memory or Alzheimer disease.
What could not be checked: the EMA monograph's safety sections, the EFSA coumarin opinion, the full LiverTox page, Commission E and WHO monographs, and the Pediatrics cinnamon challenge paper's findings.
Safety gaps: no study tested cinnamon with blood thinners or measured low-blood-sugar risk with diabetes drugs, and no human data exist for medicinal amounts in pregnancy or breastfeeding.

How new research is added

New studies are found by a saved PubMed search and are placed in a review queue. A person reads each one before it changes any evidence rating or safety wording. New publications never change ratings automatically.

Lab markers

What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".

Hormonal 1

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Testosterone and other androgens (PCOS)

No clear change in trials

Male-type hormones that are often raised in PCOS.

Low certainty

Results and what it means

Why it was measured

Key PCOS hormone marker.

Statistical vs. clinical meaning

Two small trials agree on no change.

Safety implication

None.

Study	Result	People	Product
²⁰	No significant difference from placebo	66 women with PCOS	Cinnamon powder 1.5 g a day, 12 weeks
⁵⁰	No significant difference	39 women with PCOS	1.5 g a day, 6 months

^{20 50}

Metabolic 8

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HbA1c (three-month blood sugar average, %)

Mixed results in trials

The share of haemoglobin in red blood cells coated with sugar. It reflects average blood sugar over about three months. A level of 6.5% or above is the usual cut-off for diabetes.

Mixed findings

Results and what it means

Why it was measured

The main long-term measure of diabetes control.

Statistical vs. clinical meaning

Pooled drops are small and reviewers disagree. A drop of 0.1 to 0.3 points is statistically detectable but small in practice.

Safety implication

Could add to diabetes drugs; watch for low sugar.

Study	Result	People	Product
²	-0.09 percentage points (CI 0.04 to 0.14)	Type 2 diabetes, 6 trials	Cinnamon 1 to 6 g a day
³	-0.16% (CI -0.39 to 0.02), not significant	Type 2 diabetes, 10 trials	Cinnamon 120 mg to 6 g a day
⁴⁵	-0.24% (CI -0.48 to -0.01)	Type 2 diabetes, 18 trials	Cinnamon supplements
⁷²	-0.10% (CI -0.17 to -0.03)	Umbrella of 11 meta-analyses	Cinnamon
³²	WMD 0.0 (CI -0.44 to 0.45), no difference	23 studies, very poor quality	Cinnamon
³⁵	-0.2 points vs placebo	160 adults on oral diabetes drugs	3 g a day for 90 days
¹²	53 to 45 mmol/mol, p 0.036	18 adults on metformin	Cassia 3 g a day for 12 weeks

^{2 3 45 72 32 35 12}

▼

Fasting blood glucose

Lowered in trials

Blood sugar after at least eight hours without food. 126 mg/dL or higher on repeat tests is the usual diabetes threshold.

Low certainty

Results and what it means

Why it was measured

A simple measure of daily sugar control.

Statistical vs. clinical meaning

Pooled drops of about 10 to 25 mg/dL are clinically relevant if real, but heterogeneity is extreme and trials are small.

Safety implication

Hypoglycaemia risk with diabetes drugs.

Study	Result	People	Product
³	-24.59 mg/dL (CI -40.52 to -8.67)	Type 2 diabetes, 10 trials	Cinnamon 120 mg to 6 g a day
⁴⁵	-19.26 mg/dL (CI -28.08 to -10.45)	Type 2 diabetes, 18 trials	Cinnamon
⁷⁷	-15.26 mg/dL (CI -22.23 to -8.30)	Type 2 diabetes, 28 trials, 3,054 people	Cinnamon, mainly capsules
⁷²	-10.93 mg/dL (CI -16.22 to -5.65)	Umbrella analysis	Cinnamon
³³	Inconclusive	Cochrane, 10 trials, 577 people	Mostly cassia
⁴⁴	8.59 mg/dL lower than placebo (CI 0.59 to 16.59)	150 adults, LDL 100 to 190	Ceylon extract 1 g a day
⁵⁹	No significant change	44 adults with type 2 diabetes	3 g a day, 8 weeks

^{3 45 77 72 33 44 59}

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HOMA-IR (insulin resistance estimate)

Lowered in trials

A calculation from fasting glucose and fasting insulin. Higher means more insulin resistance. It is an estimate, not a direct test.

Low certainty

Results and what it means

Why it was measured

Shows whether the body responds well to insulin.

Statistical vs. clinical meaning

A modest fall in an estimated number; the direct clamp test did not agree.

Safety implication

None specific.

Study	Result	People	Product
¹³	-0.714 (CI -1.388 to -0.04)	Type 2 diabetes or prediabetes, 16 trials	Cinnamon
⁷⁷	-0.76 (CI -1.13 to -0.39)	Type 2 diabetes, 28 trials	Cinnamon
⁷²	-0.61 (CI -0.91 to -0.31)	Umbrella	Cinnamon
⁶⁴	Clamp test: no change in insulin sensitivity	21 adults with impaired glucose tolerance	Cassia 12 g a day, 12 weeks

^{13 77 72 64}

●

Fasting insulin

No clear change in trials

The hormone insulin measured while fasting. High levels can signal insulin resistance.

Low certainty

Results and what it means

Why it was measured

Helps interpret insulin resistance.

Statistical vs. clinical meaning

Results differ between the two analyses.

Safety implication

None specific.

Study	Result	People	Product
⁴²	SMD -0.17 (CI -0.34 to 0.01), not significant	Type 2 diabetes, 24 trials	Cinnamon
⁷²	-2.01 IU/mL (CI -3.96 to -0.07)	Umbrella analysis	Cinnamon
⁵⁹	No significant change	44 adults	3 g a day

^{42 72 59}

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LDL cholesterol (mg/dL)

Mixed results in trials

The cholesterol carried in LDL particles, often called bad cholesterol. Lower is generally better for heart risk.

Mixed findings

Results and what it means

Why it was measured

Heart-risk marker measured in cinnamon trials.

Statistical vs. clinical meaning

Pooled drop of 6 to 9 mg/dL in diabetes reviews; null elsewhere and in the best-aimed trial.

Safety implication

None specific.

Study	Result	People	Product
²⁶	-6.13 mg/dL (CI -10.72 to -1.53)	Type 2 diabetes, 16 studies	Cinnamon
³	-9.42 mg/dL (CI -17.21 to -1.63)	Type 2 diabetes, 10 trials	Cinnamon
³⁸	-6.19 mg/dL (CI -13.53 to 1.16), not significant	13 trials	Cinnamon
⁴⁴	Cinnamon arm 6.05 mg/dL higher in the LDL-focused trial (not significant)	150 adults with LDL 100 to 190	Ceylon extract 1 g a day
³²	WMD 0.38 (CI -6.07 to 6.83), no difference	23 studies, very poor quality	Cinnamon

^{26 3 38 44 32}

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HDL cholesterol (mg/dL)

Mixed results in trials

The cholesterol carried in HDL particles, often called good cholesterol.

Low certainty

Results and what it means

Why it was measured

Part of the blood fat profile.

Statistical vs. clinical meaning

Changes of 0.5 to 1.7 mg/dL are too small to be meaningful.

Safety implication

None.

Study	Result	People	Product
³	+1.66 mg/dL (CI 1.09 to 2.24)	Type 2 diabetes, 10 trials	Cinnamon
²⁶	+0.64 mg/dL (CI -0.18 to 1.46), not significant	Type 2 diabetes	Cinnamon
⁵⁶	+0.47 mg/dL (CI 0.17 to 0.77)	Umbrella	Cinnamon

^{3 26 56}

▼

Triglycerides (mg/dL)

Lowered in trials

A type of fat in the blood. High levels raise heart and pancreas risk.

Low certainty

Results and what it means

Why it was measured

Often lowers in cinnamon trials.

Statistical vs. clinical meaning

Several reviews agree on a fall; an umbrella analysis found none.

Safety implication

None.

Study	Result	People	Product
³⁸	-23.91 mg/dL (CI -34.54 to -12.40)	13 trials, 750 people	Cinnamon
²⁶	-26.27 mg/dL (CI -38.93 to -13.61)	Type 2 diabetes, 16 studies	Cinnamon
⁶⁵	-8.85 mg/dL (CI -14.16 to -3.54)	Metabolic syndrome, 12 studies	Cinnamon
⁵⁶	-0.13 mg/dL (not significant)	Umbrella	Cinnamon

^{38 26 65 56}

▼

Total cholesterol (mg/dL)

Lowered in trials

All cholesterol in the blood.

Low certainty

Results and what it means

Why it was measured

Part of the blood fat profile.

Statistical vs. clinical meaning

Consistent small falls except in the umbrella analysis.

Safety implication

None.

Study	Result	People	Product
³⁸	-13.92 mg/dL (CI -24.36 to -3.48)	13 trials	Cinnamon
²⁶	-13.93 mg/dL	Type 2 diabetes	Cinnamon
⁶⁵	-7.34 mg/dL (CI -9.27 to -5.41)	Metabolic syndrome	Cinnamon
⁵⁶	-1.01 mg/dL (CI -2.02 to 0.00)	Umbrella	Cinnamon

^{38 26 65 56}

Inflammatory 1

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C-reactive protein (CRP, mg/L)

Mixed results in trials

A blood protein that rises with inflammation.

Low certainty

Results and what it means

Why it was measured

Inflammation marker.

Statistical vs. clinical meaning

Direction favours cinnamon, but the best single trial was null.

Safety implication

None.

Study	Result	People	Product
⁶⁰	-0.81 mg/L (CI -1.36 to -0.26)	6 studies, 285 people	Cinnamon
⁷⁵	-2.22 mg/L (CI -3.74 to -0.69)	12 trials	Cinnamon powder 1.5 to 4 g a day
⁵⁶	-1.33 (CI -2.66 to 0.00), borderline	Umbrella	Cinnamon
¹⁰	hs-CRP p 0.29 between groups	44 adults with type 2 diabetes	3 g a day, 8 weeks

^{60 75 56 10}

Other 4

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Blood sugar after eating or a glucose drink

Mixed results in trials

Blood sugar measured one to two hours after a meal or a measured sugar drink.

Mixed findings

Results and what it means

Why it was measured

Shows how much sugar spikes after food.

Statistical vs. clinical meaning

Single-dose results disagree and are in small groups.

Safety implication

None specific.

Study	Result	People	Product
⁷⁷	-39.22 mg/dL (CI -63.90 to -14.55; I2 100%)	Type 2 diabetes trials	Cinnamon
⁵	Area under curve 0-60 min -21.2% (p<0.05); 0-120 min -14.8% (not significant)	18 healthy adults	Ceylon extract 1 g
⁶³	No effect	10 adults with impaired glucose tolerance	Ceylon 6 g
⁵²	No effect	36 adults with type 2 diabetes	Water extract
⁷³	Glucose peak rise 9.56 vs 11.73 mg/dL (p 0.027)	18 adults with prediabetes	Cinnamon 4 g a day for 4 weeks

^{77 5 63 52 73}

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Systolic blood pressure (top number, mmHg)

Mixed results in trials

The pressure in the arteries as the heart beats.

Low certainty

Results and what it means

Why it was measured

Main blood pressure outcome.

Statistical vs. clinical meaning

Reviews disagree.

Safety implication

May add to blood pressure drugs.

Study	Result	People	Product
¹⁹	-5.17 mmHg (CI -9.35 to -0.99)	9 trials, 641 people	Cinnamon
¹⁵	-0.61 mmHg (CI -1.36 to 0.14), not significant	8 trials, 582 people	Cinnamon
⁶²	-3.4 vs +1.9 mmHg (p 0.06); gone after adjusting	59 adults with type 2 diabetes	1.2 g a day for 12 weeks

^{19 15 62}

▼

Diastolic blood pressure (bottom number, mmHg)

Lowered in trials

The pressure between heartbeats.

Low certainty

Results and what it means

Why it was measured

Second blood pressure outcome.

Statistical vs. clinical meaning

Small fall in both reviews, but the size differs by 3.5 times.

Safety implication

May add to blood pressure drugs.

Study	Result	People	Product
¹⁹	-3.36 mmHg (CI -5.67 to -1.04)	9 trials	Cinnamon
¹⁵	-0.93 mmHg (CI -1.55 to -0.32)	8 trials	Cinnamon

^{19 15}

▼

Body weight and BMI

Lowered in trials

Body weight in kg and body mass index (weight divided by height squared).

Low certainty

Results and what it means

Why it was measured

Outcome of weight-loss claims.

Statistical vs. clinical meaning

Under 1 kg; reviews in diabetes found nothing.

Safety implication

None.

Study	Result	People	Product
⁶⁹	Weight -0.92 kg; BMI -0.40 kg/m2	21 trials, 1,480 people	Cinnamon
³⁰	Weight -0.67 kg; BMI -0.45	Umbrella of 7	Cinnamon
⁴⁵	BMI -0.05 kg/m2 (not significant)	Type 2 diabetes, 18 trials	Cinnamon

^{69 30 45}

Safety

What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.

Main points to know 7

Cassia cinnamon (the common supermarket kind) contains coumarin, which can harm the liver in sensitive people. Cassia (Cinnamomum cassia, also called C. aromaticum) averages about 3,000 mg of coumarin per kg, with a highest measured level of 10,000 mg/kg, according to the German risk agency BfR. Ceylon cinnamon (C. verum, 'true cinnamon') has low levels. The European tolerable daily intake for coumarin is 0.1 mg per kg of body weight a day. Using the BfR's average figures, about 2 g of cassia a day reaches that limit for a 60 kg adult, and about 0.5 g a day for a 15 kg child. A small group of people is more sensitive than animals, and liver effects were seen when coumarin was used as a drug. A short overshoot is not thought dangerous; regular large amounts of cassia are the concern. Authoritative guidance ^{78 1 37 24}
Ceylon and cassia are different spices, and most shops and products do not say which. In an Italian survey of 34 cinnamon samples, about 51% were cassia, 10% probably a blend and only 39% Ceylon cinnamon. A 2023 chemical comparison found Ceylon (C. verum) had the lowest coumarin of four species and described cheaper, liver-toxic species being used to adulterate it. NCCIH notes products often do not state the type or plant part. If you use cinnamon often or as a supplement, check the label for Cinnamomum verum or zeylanicum. Authoritative guidance ^{37 53 83}
Rare cases of liver injury have been reported with cinnamon supplements. LiverTox describes cinnamon as generally well tolerated but implicated in isolated, rare reports of acute liver injury. We found two published case reports: a 73-year-old woman who developed hepatitis about a week after starting cinnamon supplements while taking a statin, and a 34-year-old woman with a mixed liver injury after long use of cinnamon for weight loss; both recovered after stopping. Neither report proves cinnamon was the cause, and the species was not stated. Case report ^{23 7 70}
Cinnamon may add to the effect of diabetes medicines. Cinnamon lowers blood sugar a little in many trials. Taken with insulin or tablets that lower sugar it could, in theory, add to the effect and cause low blood sugar. Trials that added cinnamon to usual diabetes drugs (for example gliclazide and metformin) did not report severe low sugar in the abstracts we read, but they were small and short. Tell the person who manages your diabetes before taking cinnamon supplements. Pharmacological theory ^{35 36 12}
Cinnamon flavouring can inflame the mouth. Cinnamaldehyde, the flavour compound, can cause an allergic-type inflammation inside the mouth. In a retrospective series of 74 patients, lesions on the cheek lining and tongue (white, red or ulcerated) all cleared within a week after stopping cinnamon gum or sweets. Such reactions can be mistaken for other mouth problems. Case series ^{29 9}
Pregnancy and breastfeeding: stay to food amounts. NCCIH says food amounts of both cassia and Ceylon appear safe in pregnancy, and that larger amounts of Ceylon are considered unsafe in pregnancy. LactMed says no data exist on cinnamon in nursing mothers or babies. In rats, a large cinnamon extract dose given to nursing mothers led to belly fat, high insulin and a mildly fatty liver in the grown-up male offspring; this is animal evidence only. If you are pregnant or nursing, keep to ordinary food use and ask your clinician before supplements. Authoritative guidance ^{83 47 46}
Never swallow dry cinnamon powder as a dare, and do not use cinnamon oil neat. NCCIH warns against the 'cinnamon challenge' of swallowing a spoonful of dry powder. Ground cinnamon contains cellulose fibres that persist in the lungs, and breathing it in can cause lasting lung inflammation; cinnamon oils can irritate the skin and cause ulcers or dermatitis. Misuse usually causes mild to moderate symptoms but some cases need hospital care. Authoritative guidance ^{83 28 16}

Side effects 8

Effect	How often	Severity and recovery	Evidence
Bloating, indigestion, heartburn, nausea LactMed lists occasional bloating, dyspepsia, heartburn and nausea. The Cochrane review found adverse reactions to oral cinnamon infrequent and generally mild. No frequency figure is given.	Not established	mild Settles after stopping or reducing	Authoritative guidance ^{47 33}
Mouth inflammation or sores (contact stomatitis) from cinnamon gum, sweets, toothpaste or mouthwash Caused by cinnamon flavouring (cinnamaldehyde). How common it is across all users is not known.	Not established	mild to moderate Cleared within a week of stopping in all 74 cases in one series	Case series ^{29 9}
Allergic reactions NCCIH says larger amounts or long-term use may cause allergic reactions.	Not established	mild to serious Usually settles after avoiding it	Authoritative guidance ⁸³
Liver injury Rare and isolated per LiverTox. Cassia contains coumarin; species not stated in the cases.	Not established	moderate to serious Both reported cases recovered after stopping	Case report ^{23 7 70}
Low blood sugar when combined with diabetes medicines Theoretical. Trials adding cinnamon to diabetes medicines did not report this in their abstracts.	Not established	moderate Reversible with treatment	Pharmacological theory ³³
Skin irritation, ulcers or burns from cinnamon oil Cinnamon oils contain local irritants.	Not established	mild to moderate Usually heals after stopping	Authoritative guidance ²⁸
Lung inflammation from breathing in dry powder Associated with swallowing or inhaling spoonfuls of ground cinnamon.	Not established	moderate to serious Chronic inflammation and fibrosis are described	Authoritative guidance ^{28 16}
Less feeling of fullness after a cinnamon drink In 21 healthy adults a 2 g cinnamon infusion reduced fullness and raised food eaten at the next meal. Not a safety harm, but relevant to anyone using cinnamon for appetite.	Not established	mild Short-lived	Controlled trial ⁵⁷

Liver

Liver is the main safety question, and it is mostly about cassia. Coumarin, found in much higher amounts in cassia than in Ceylon cinnamon, is liver-toxic in a sensitive subgroup of people when taken as a drug; the European tolerable daily intake of 0.1 mg per kg of body weight a day was derived from such human data. LiverTox says cinnamon has been implicated in isolated, rare reports of acute liver injury. We found two published cases. In the other direction, a meta-analysis of 7 trials (256 people) found no significant change in ALT, AST or ALP overall, and a 12-week trial of 12 g of cassia a day in 9 treated people with impaired glucose tolerance saw no change in liver enzymes. A retrospective study of 129 Japanese patients on cinnamon-bark Kampo medicines found 76% above the coumarin TDI but no more liver test abnormalities than in those below it, and none traced to cinnamon. ^{23 7 70 1 24 43 64 78}

How often. No frequency of cinnamon-related liver injury was found. The BfR said no cinnamon-linked liver damage had been reported in the literature up to its 2012 FAQ; two cases have been published since that we found.

Monitoring. No agency monitoring advice for cinnamon was found. Stop and seek care for yellow skin or eyes, dark urine, pale stools, severe tiredness or belly pain. People with liver disease, or who take liver-toxic medicines, should avoid cassia supplements.

This is a safety connection. It is not evidence that Cinnamon supports liver health.

Medicines and supplements 6

With	Why it matters	Importance	Evidence	What to do
Insulin, sulfonylureas (for example gliclazide, glibenclamide) and other diabetes medicines prescription	Cinnamon lowers blood sugar a little, so the effects may add together.	Trials that added cinnamon to gliclazide or metformin reported glucose benefits; their abstracts do not report severe low sugar. No study was designed to test hypoglycaemia risk.	Pharmacological theory Low certainty ^{36 35 12 33}	Tell your doctor or pharmacist before starting cinnamon supplements, check sugar as advised and know the signs of low sugar (shakiness, sweating, confusion).
Liver-toxic medicines (for example some pain, cancer, tuberculosis or anti-seizure drugs) and statins prescription	Coumarin in cassia can stress the liver; the hepatitis case report involved cinnamon with a statin.	One case report only; authors suggest avoiding the combination. Cannot show cause.	Case report Very low certainty ^{7 1}	Avoid cassia supplements if you take medicines that can harm the liver unless your doctor agrees; have liver tests as advised.
Blood pressure and cholesterol medicines prescription	Small blood pressure and cholesterol falls were seen in some trials.	Not tested directly. Trials in people already on drugs found small effects only.	Pharmacological theory Not enough evidence ^{19 26}	Mention cinnamon supplements at medicine reviews.
Warfarin and other blood thinners prescription	Cassia contains coumarin, a different substance from the blood-thinning drugs called coumarins, but the name causes concern.	No interaction report or study was found in our search. Not verified either way.	Pharmacological theory Not enough evidence	Ask your pharmacist if you take a blood thinner and want to use cinnamon supplements.
An anticancer medicine and nicotine (NCCIH, theoretical) prescription	NCCIH states that, for theoretical reasons, some cinnamon components may interact with an anticancer medicine or nicotine; the medicine is not named in the summary we read.	No clinical data seen.	Pharmacological theory Not enough evidence ⁸³	Check with your oncology team or pharmacist before using cinnamon supplements during cancer treatment.
Other herbs and supplements that lower blood sugar (for example berberine) herb-supplement	Effects may add together. One trial combined 600 mg cinnamon with 1,200 mg berberine and saw lower fasting sugar, HbA1c and LDL; the effect cannot be credited to cinnamon.	No problems reported in the abstract.	Controlled trial Low certainty ⁴⁰	Do not stack several blood-sugar-lowering supplements without medical advice.

Who should check first 7

Situation	Advice	Evidence
Allergy to cinnamon or cinnamaldehyde, or a past mouth reaction to cinnamon gum, sweets or toothpaste	Avoid cinnamon products and flavourings.	Case series ^{29 9 83}
Liver disease, or taking medicines that can harm the liver	Avoid cassia in supplement amounts. NCCIH notes prolonged use may be a concern for sensitive people such as those with liver disease.	Authoritative guidance ^{83 1 23}
Pregnancy	Food amounts appear safe per NCCIH; avoid medicinal or supplement amounts, especially larger amounts of Ceylon, which NCCIH calls unsafe in pregnancy.	Authoritative guidance ⁸³
Breastfeeding	No safety data exist for medicinal amounts; stay with food amounts. A rat study of a large extract dose in nursing mothers showed effects on the grown-up offspring.	Authoritative guidance ^{47 46}
Children	A small child can reach the coumarin limit with about 0.5 g of average cassia a day (BfR). Prefer Ceylon for regular use. Never give dry cinnamon powder as a dare or game.	Authoritative guidance ^{78 16}
Diabetes treated with insulin or sugar-lowering tablets	Not forbidden, but talk to your care team first.	Pharmacological theory ³³
Mouth ulcers, sores or inflammation	Avoid cinnamon gum, sweets and oil-based mouthwash until healed.	Case series ²⁹

Overdose, product quality and regulators

Summary. Cinnamon as a food spice is very widely eaten. The toxicity concerns are (1) coumarin in cassia, which can affect the liver in sensitive people above the tolerable daily intake; (2) cinnamon oil and dry powder, which irritate skin, mouth and lungs; (3) cinnamaldehyde allergy in the mouth.

Animal. Pure coumarin was hepatotoxic and carcinogenic in animals; the European Food Safety Authority discounted a genotoxic mechanism in 2004, which allowed a TDI to be set (from Abraham 2010). Cinnamaldehyde is metabolised to cinnamyl alcohol, methyl cinnamate and cinnamic acid, and a review notes a potential toxicity concern for the compound (Zhu 2017, animal and lab work).

Human doses studied. Trials have used cinnamon from about 120 mg to 12 g a day for 4 to 18 weeks. One 12-week trial gave 12 g of cassia a day to 9 people with impaired glucose tolerance without a change in liver enzymes. Such doses would far exceed the coumarin TDI if the cinnamon was average cassia, so the lack of liver signal should not be read as proof of safety.

High dose or long term signals. Liver injury case reports; Japanese Kampo patients mostly exceeded the coumarin TDI without a clear rise in liver test abnormalities (retrospective, no placebo).

Overdose response. No cinnamon overdose guideline was found in what we read. Swallowing or inhaling dry powder can cause choking, lung inflammation and, rarely, hospital admission.

Genotoxicity. For coumarin, genotoxicity was discounted by EFSA in 2004 per Abraham 2010. Other compounds were not reviewed.

Toxic plant parts. The inner bark is the part used as spice and medicine. Cinnamon bark oil, leaf oil and other plant parts were not reviewed in detail; undiluted essential oil is an irritant.

The main 'contamination' issue is the mix-up between cassia and Ceylon, which changes coumarin exposure. Coumarin also appears in cinnamon baked goods.

Cassia sold as 'cinnamon'. In 34 cinnamon samples from the Italian market, about 51% were cassia, 10% blends and 39% Ceylon. Many cinnamon foods exceeded the then EU limit of 2 mg/kg. ³⁷

Adulteration of Ceylon cinnamon. A 2023 study of four Cinnamomum species says the valued Ceylon type is frequently adulterated with cheaper hepatotoxic substitutes (C. burmannii, C. cassia, C. loureiroi), and that chemical profiling can tell them apart. ⁵³

Coumarin in cinnamon baked goods. In German foods, bakery products and cereals averaged 9 mg/kg of coumarin, with some cinnamon cookies up to 88 mg/kg. EU limits since 2011: 50 mg/kg for traditional or seasonal cinnamon bakery goods and 5 mg/kg for desserts; no limit for cinnamon as a spice (BfR). ^{58 78}

Body	Action	Date
German Federal Institute for Risk Assessment (BfR) (Germany)	FAQ on coumarin in cinnamon: TDI 0.1 mg/kg body weight a day (same as EFSA), applying to sensitive consumers; advises moderation with cassia and Ceylon for frequent home use; supplements may contain high coumarin. source	2012-09-27
US National Center for Complementary and Integrative Health (NCCIH) (United States)	Cinnamon is likely safe in food amounts; larger amounts or long-term use may cause stomach problems or allergic reactions; cassia contains coumarin linked to liver problems; food amounts safe in pregnancy but larger amounts of Ceylon unsafe; warns against the cinnamon challenge. source
LiverTox, US National Institute of Diabetes and Digestive and Kidney Diseases (United States)	Cinnamon: generally well tolerated but implicated in isolated, rare reports of acute liver injury. source	2026-07-01
LactMed, US National Library of Medicine (United States)	No data on cinnamon in nursing mothers or infants; cassia has high coumarin; Ceylon cinnamon is generally recognised as safe (GRAS) as a flavouring by the FDA, as stated by LactMed. source	2026-10-15

When to get medical help

Yellow skin or eyes, dark urine, pale stools, severe tiredness or belly pain after starting cinnamon (possible liver injury): stop and get medical care.
Swelling of the face, lips or throat, trouble breathing or widespread hives (serious allergy): call emergency services.
Choking, coughing, wheezing or trouble breathing after swallowing or breathing in dry cinnamon powder: get urgent care.
Shakiness, sweating, confusion or fainting in someone on diabetes medicines (low blood sugar): treat with fast sugar and seek care.
Painful mouth sores or swelling that do not heal within a week after stopping cinnamon gum or sweets: see a dentist or doctor.

Stop the supplement and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.

General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.

Frequently asked questions

Does cinnamon lower blood sugar or help with diabetes?

Maybe a little, but the research disagrees. Several pooled analyses of small trials in type 2 diabetes find fasting blood sugar lower by roughly 10 to 25 mg/dL and HbA1c lower by 0.1 to 0.6 points. The Cochrane review (2012) called the evidence insufficient, and a 2022 analysis of studies it called very poor quality found no difference in HbA1c. We rate HbA1c as mixed and fasting sugar as low. Cinnamon is not a replacement for diabetes treatment.

^{33 32 42 77 3 72}

What is the difference between Ceylon and cassia cinnamon?

They are different species. Ceylon cinnamon (Cinnamomum verum, also called true cinnamon) is low in coumarin. Cassia (Cinnamomum aromaticum, usually written C. cassia) is the cheaper, more common kind and contains far more coumarin. Most studies on blood sugar used cassia or did not name the species. Labels often just say cinnamon; look for Cinnamomum verum or zeylanicum on the label.

^{78 53 37 81 80}

Can cinnamon harm the liver?

Cassia can, in sensitive people, because of its coumarin. LiverTox reports isolated, rare cases of liver injury with cinnamon, and we found two published case reports (both recovered after stopping). Short trials, including a 12-week cassia trial and a meta-analysis of seven trials, saw no rise in liver enzymes overall. That does not rule out rare reactions. People with liver disease should avoid cassia supplements.

^{23 7 70 43 64 1}

Is it safe to take cinnamon with diabetes medicines?

Cinnamon lowers blood sugar a little, so in theory it could add to insulin or tablets and cause low blood sugar. The trials that added cinnamon to usual diabetes drugs did not report severe lows in their abstracts, but they were small. Tell your doctor or pharmacist before starting a cinnamon supplement.

^{35 36 12 33}

Does cinnamon lower cholesterol or blood pressure?

Slightly in some analyses, not in others. Reviews in people with type 2 diabetes find lower triglycerides and total cholesterol; an umbrella analysis found changes of about 1 mg/dL. For blood pressure, one review found a 5 mmHg fall in the top number and another found almost none. A Ceylon trial designed to lower LDL cholesterol found no significant drop. We rate these low or mixed.

^{26 38 56 19 15 44}

Does cinnamon help with weight loss?

Barely. Pooled trials show an average loss under 1 kg, and one small trial found a cinnamon drink slightly reduced fullness. One woman developed liver injury after taking cinnamon for weight loss over a long time (a single case report).

^{69 30 57 70}

Does cinnamon help polycystic ovary syndrome (PCOS)?

Possibly for insulin resistance. Pooled small trials find lower fasting sugar and insulin resistance, but the trials are few and one pilot found no change in insulin resistance, lipids or androgens. For hormones and ovaries the evidence is insufficient. Trials of combination products cannot be credited to cinnamon.

^{22 21 66 20 50 39}

Is cinnamon safe in pregnancy or while breastfeeding?

In food amounts, NCCIH says both cassia and Ceylon appear safe in pregnancy, but it considers larger amounts of Ceylon unsafe in pregnancy. For breastfeeding, LactMed says no data exist on the safety of cinnamon for nursing mothers or babies. In rats, a large extract dose given to nursing mothers affected the grown offspring. Stay with food amounts and ask your clinician about supplements.

^{83 47 46}

Is cinnamon safe for children, and what is the cinnamon challenge?

Children reach the coumarin limit sooner because they weigh less, so regular use of cassia is the concern. The 'cinnamon challenge' means swallowing a spoonful of dry powder as a dare. NCCIH warns it can cause serious harm; ground cinnamon fibres can stay in the lungs and cause lasting inflammation.

^{78 83 28 16}

Can cinnamon cause mouth sores or allergy?

Yes, in some people. Cinnamon flavouring (cinnamaldehyde) in gum, sweets, toothpaste or mouthwash can cause mouth inflammation. In a series of 74 patients the lesions cleared within a week of stopping the product. Undiluted cinnamon oil can also irritate or burn skin and mouth.

^{29 9 28}

Does cinnamon help memory or Alzheimer disease?

There is no human evidence. Lab and animal work suggests cinnamon extract may block clumping of tau and amyloid-beta proteins, but no trial has tested this in people. We rate it insufficient.

⁴¹

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Editorial transparency

Written by: AlternativeMed editorial team. Research compiled with AI assistance, then checked against PubMed records.
Medical review: None. This page has not been reviewed by a physician or pharmacist.
First published: 2026-10-25
Last substantive update: 2026-10-25
How we research: We searched PubMed and read abstracts (not full texts) for nearly all studies. We read summaries of the NCCIH cinnamon page and the German BfR coumarin FAQ, checked plant names in GBIF and the NCBI taxonomy, and compounds in PubChem. Some sources were not verified: the EMA/HMPC monograph's safety sections, the EFSA coumarin opinion, the full LiverTox page (its likelihood score was not seen), the FDA statement (known only through LactMed), and the Commission E and WHO monographs. The abstract of one Pediatrics paper on the cinnamon challenge was not available. Certainty ratings are the compiler's own reading, not formal grades. No study is cited that we could not verify. One often-cited 2003 diabetes trial carries a journal Expression of Concern and is not relied on.
How we rate evidence: See "How we rate evidence" in the Evidence tab.
Independence: No product is promoted on this page. No affiliate links are shown. If one is added later it will be labelled and kept apart from the evidence.

Sources 83

Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.

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. German Federal Institute for Risk Assessment (BfR): FAQ on coumarin in cinnamon and other foods (27 Sept 2012). . . (summary-only)
. EMA/HMPC community herbal monograph on Cinnamomum verum J.S. Presl, cortex and corticis aetheroleum (compiled 10 May 2011). . . (summary-only)
. GBIF Backbone Taxonomy: Cinnamomum aromaticum Nees (usageKey 3033982). . . (full-text)
. GBIF Backbone Taxonomy: Cinnamomum verum J.Presl (usageKey 3033987). . . (full-text)
. NCBI Taxonomy: Cinnamomum verum (taxid 128608), Cinnamomum burmannii (119261) and the entry for cassia (taxid 230708). . . (summary-only)
. NCCIH: Cinnamon. . . (summary-only)

Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.