Spices · Spice
Sumac
Rhus coriaria · also called Sumach, zumaque (Spanish)
Sumac is a sour, deep red spice made from the dried, ground fruit of Rhus coriaria. It is used on salads, meat and rice in Middle Eastern cooking. Trials of sumac powder and supplements give mixed results for blood sugar, and a small possible drop in diastolic blood pressure. None tested sumac as a seasoning on food. Poison sumac is a different, dangerous plant. People with cashew allergy should ask an allergist first.
General information, not medical advice. Last substantive update · Not medically reviewed. A named clinician has not signed off on this page. How this page is made
About Sumac
Sumac is a sour, red spice that is mostly used for flavour. Small trials of sumac powder and supplements show mixed results for blood sugar and no clear effect on weight. It is a food seasoning, not a proven remedy. The key cautions are not to confuse it with poison sumac and to ask an allergist if you have a cashew allergy.
What it is
Sumac (Rhus coriaria) is a plant in the cashew family, Anacardiaceae. The spice is the dried, ground fruit and is popular in the Mediterranean region as a sour seasoning and condiment.
USDA FoodData Central has no standard reference entry for sumac, so we give no nutrient numbers. One branded product record lists the ingredients as sumac berries and salt, so some ground sumac has added salt. Sumac is used in small amounts, so it is not a big source of calories or vitamins.
What the research shows
Pooled reviews of small trials disagree about blood sugar. A 2021 pooling of 6 trials (278 people) found no significant effect of sumac powder. A 2024 pooling of 15 trials found lower fasting glucose, HbA1c and insulin resistance, and a 2026 pooling of 15 trials (917 people) also reported better blood sugar and blood fats. These pooled reviews share many of the same trials.
The 2024 review found diastolic blood pressure about 3 mmHg lower, with no effect on weight, BMI or waist size. The 2026 review found no significant effect on inflammation markers.
Almost all trials used powder, supplements or capsules of a seed extract for 4 to 12 weeks. No trial of sumac used as a seasoning was found.
Seasoning versus supplements
The trials used powder, supplements or seed-extract capsules. A sprinkle of ground sumac on food is a much smaller exposure and was not tested. Do not assume the trial results apply to cooking amounts, or the other way round.
Amounts
This page gives no amounts to eat or take. Ask a doctor, pharmacist or dietitian what is right for you, especially if you have diabetes, take medicines or have a cashew allergy.
At a glance
Traditional uses history, not proof
- Ground over salads, grilled meat, fish and rice as a sour seasoning
- Traditional medicine for haemorrhoids, wounds, diarrhoea, ulcer and eye inflammation (2021 review; no trial support read)
- Long use as food is not proof that it treats any condition
Studied for research
- Blood sugar markers, mixed (powder and supplements in trials)
- Diastolic blood pressure, low certainty (small drop in a test number)
- Blood fats, insufficient (pooled results disagree)
- Weight and waist size, insufficient (no effect on weight)
- Inflammation markers, low certainty of no effect
- Antioxidant effects, very low (cells and animals only)
Main compounds
- Flavonoids
- Tannins
- Other polyphenols
- Organic acids
Common forms
- Ground sumac as a seasoning (some products contain added salt)
- Whole dried berries
- Sour drink made by steeping the fruit
- Powder, supplement or seed-extract capsules (the form used in trials)
Research links: PubMed: 2024 pooling of 15 trials on blood pressure, blood sugar and body size · PubMed: 2021 pooling of 6 trials on blood sugar · MedlinePlus: Poison Ivy, Oak, and Sumac · Research Library · Genes & Biomarkers Library
What it is and its history
- Accepted scientific name
- Rhus coriaria
- Naming authority
- L. (GBIF accepted)
- Common names
- Sumac (English); Sumach (English); Zumaque (Spanish)
- Family or group
- Anacardiaceae (the cashew family), as given by GBIF. The family also includes cashew, mango, pistachio, pink peppercorn and poison sumac.
- Classification
- Plantae > Tracheophyta > Magnoliopsida > Sapindales > Anacardiaceae > Rhus > Rhus coriaria
- Native range
- Not verified from a source read. Reviews describe it as a spice used especially in the Mediterranean region.
- Habitat
- Not verified from a source read.
- What it looks like
- Roots: Not verified.; Stems: Not verified.; Leaves: Not verified.; Flowers: Not verified.; Fruit: The spice is the dried, ground fruit (berry). Colour and size were not described in a source read.
- Cultivation
- Not verified from a source read.
- Harvest and processing
- Sold as ground sumac (some with salt added), whole dried berries, a steeped sour drink and a cooked paste, according to the existing nutrient summary; not re-checked.
- Look-alikes and adulterants
- Name: Poison sumac (Toxicodendron vernix); Note: A different plant in the same family with the same common-name word. Its sap (urushiol) causes a blistering rash and can be dangerous to eat or burn. GBIF lists it as an accepted species in genus Toxicodendron, not Rhus. Never gather wild sumac to eat.; Name: Other Rhus species; Note: Other plants in the genus Rhus are also called sumac. Only Rhus coriaria was researched for this page.
- Sustainability and conservation
- Not assessed.
Photographs
Traditional use and history history, not clinical proof
| Tradition or era | Documented use | Source |
|---|---|---|
| Traditional medicine of the Mediterranean region | Used for haemorrhoids, wound healing, diarrhoea, ulcer and eye inflammation, according to a 2021 review. | p33430013 |
| Cooking | A popular spice, condiment and flavouring, especially in the Mediterranean region (2021 review). Details of cuisines and history were not verified from a source read. | p33430013 |
Traditional use shows how it was used. It does not show that it works or is safe today.
What is inside, and how it may work
What it 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 |
|---|---|---|---|---|
| Flavonoids | polyphenol | Fruit | Named as a class in the review abstract; antioxidant activity in lab studies. 2 | Lab |
| Tannins | polyphenol | Fruit | Named as a class in the review abstract. 2 | Lab |
| Other polyphenols | polyphenol | Fruit | Named as a class in the review abstract. 2 | Lab |
| Organic acids | acid | Fruit | Named as a class in the review abstract. The sour taste of sumac is usually attributed to acids, but which acid and how much was not verified from a source read. 2 | Lab |
Mechanisms, receptors and pathways
| Target or pathway | Gene or receptor | What was found | Level |
|---|---|---|---|
| Antioxidant activity | Not specified | A 2021 review describes antioxidant capacity of sumac extracts and many cellular effects in cells and animals. This is lab and animal work and does not show that the same happens in people eating sumac. 2 | Lab |
Absorption, metabolism and elimination
- Absorption
- Not found.
- Distribution
- Not found.
- Metabolism
- Not found.
- Elimination
- Not found.
- Bioavailability
- Not established in the sources read.
Isolated compounds versus whole extracts
The trials used sumac powder, supplements or capsules of a seed extract. A sprinkle of the ground fruit on food is a much smaller exposure and was not tested. Findings for extracts do not carry over to the spice, and findings for the spice do not carry over to extracts.
Nutritional composition
No standard USDA reference entry for sumac was found, so no nutrient numbers are given. One branded product record in the USDA FoodData Central database, "Ground sumac", lists sumac berries and salt as its ingredients and a serving of 0.6 g (1/4 teaspoon); its nutrient table could not be opened. Sumac is eaten in small amounts as a sour seasoning, so it is not a significant source of calories or vitamins, and some ground sumac contains added salt. This is not advice about how much to eat.
1 mixed findings2 low certainty1 very low certainty3 not enough evidence
What was looked at
The 7 benefits and uses checked for Sumac, each with how strong the evidence is. Tap one to open it.
- Blood sugar markers (powder and supplements in trials)Mixed findings
- Blood pressure (diastolic)Low certainty
- Blood fats (cholesterol and triglycerides)Not enough evidence
- Weight, BMI and waist sizeNot enough evidence
- Inflammation markersLow certainty
- Antioxidant and other effects in cells and animalsVery low certainty
- Traditional uses (haemorrhoids, wounds, diarrhoea, ulcer, eye inflammation)Not enough evidence
Lab markers tracked in the studies
Fasting blood glucoseHbA1c (average blood sugar over about 3 months)Diastolic blood pressureBlood lipids (total cholesterol, LDL, HDL, triglycerides)Body weight, BMI and waist circumferenceInflammatory markers
What is Sumac good for?
The main studied uses and how strong the human evidence is for each. Almost all results are for sumac powder, supplements or seed-extract capsules, not for sumac used as a seasoning.
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.
Blood sugar markers (powder and supplements in trials)
Mixed findingsPooled trials disagree. A 2021 pooling of 6 trials found no significant effect of sumac powder on any blood sugar measure. A 2024 pooling of 15 trials and a 2026 pooling of 15 trials reported improvements. All of this is powder or supplements, not a sprinkle of sumac on food. Sumac is not a treatment for diabetes.
4 studiesPowder, supplements or seed-extract capsules for 4 to 12 weeks. Amoun…
Studies, doses and limits
What the trials found
2021: 6 controlled trials (278 people) of sumac powder; the authors report no significant effect on fasting glucose (-7.08 mg/dl, 95% CI -14.85 to 0.70), HbA1c, HOMA-IR or insulin. 2024: 15 randomised trials; fasting glucose -5.15 mg/dL (95% CI -8.73 to -1.57), insulin -1.95 uIU/ml, HbA1c -0.48% (95% CI -0.84 to -0.12) and HOMA-IR -0.71 (95% CI -1.14 to -0.27) were lower, and the authors say higher doses or longer use looked more promising. 2026: 15 trials (917 people, 4 to 12 weeks) reported significant improvement in glycemic measures, with no numbers in the abstract. 2025: a double-blind trial in 60 people with type 2 diabetes using capsules of sumac seed extract for 12 weeks found fasting sugar and HbA1c differed from control (p<0.01), with no values in the abstract.
Results
Mixed. The oldest pooling found nothing; the two newer ones and a small 2025 trial found lower blood sugar markers. The pooled reviews share many of the same trials, so they are not independent confirmations.
Effect sizes as reported
2024 pooling: fasting glucose -5.15 mg/dL; HbA1c -0.48 percentage points. 2021 pooling: no significant effect.
Why this rating
Mixed because the pooled reviews disagree, trials were small and short, products and amounts varied, and the 2021 abstract has an HbA1c interval that does not fit its P value. The newer reviews are favourable but give little detail in their abstracts.
Form and dose studied
Powder, supplements or seed-extract capsules for 4 to 12 weeks. Amounts are not given here.
Who was studied
Adults; some trials were in people with type 2 diabetes. The abstracts do not say how many.
Limits
Trials used sumac powder, supplements or seed-extract capsules, not a sprinkle on food. Small, short trials. Tight blood sugar control needs a clinician, not a spice.
Why researchers looked
Sumac is a Middle Eastern spice rich in plant compounds, and researchers in the region have asked whether it changes blood sugar.
Traditional use
Sumac is used as a ground, dried, sour red spice on salads, meat, fish and rice, and in drinks. Long use as food is not proof that it treats any condition.
Proposed mechanism Unknown
Not established in people. Reviews mention antioxidant and insulin-like effects seen in cells and animals, which do not show the same happens in people.
A proposed mechanism does not show that the effect happens in people.
If you take diabetes medicines, ask a pharmacist before using sumac supplements or extracts. No source read describes an interaction; this is a cautious inference from the trial results and is labelled as such.
Blood pressure (diastolic)
Low certaintyA 2024 pooling of 15 trials found diastolic blood pressure (the lower number) about 3 mmHg lower with sumac. That is a small change in a test number, not proof of fewer heart problems. The abstract does not report the upper number.
1 studiesSumac powder or supplements in trials; details not in the abstract.
Studies, doses and limits
What the trials found
The 2024 meta-analysis of 15 randomised trials found sumac lowered diastolic pressure by 2.88 mmHg (95% CI -4.22 to -1.54). The abstract does not state a systolic pressure result.
Results
A small drop in diastolic pressure in pooled supplement trials. Whether it lasts or helps health outcomes is unknown.
Effect sizes as reported
Diastolic BP -2.88 mmHg (95% CI -4.22 to -1.54).
Why this rating
Low: a single pooling, small short trials, no systolic result in the abstract and no information on heart outcomes.
Form and dose studied
Sumac powder or supplements in trials; details not in the abstract.
Who was studied
Adults in 15 trials.
Limits
Trials used sumac powder, supplements or seed-extract capsules, not a sprinkle on food. A test number, not heart attacks or strokes.
Why researchers looked
Sumac is rich in plant compounds that are being tested for heart-related risk factors.
Traditional use
Sumac is used as a ground, dried, sour red spice on salads, meat, fish and rice, and in drinks. Long use as food is not proof that it treats any condition.
Proposed mechanism Unknown
Not established.
A proposed mechanism does not show that the effect happens in people.
If you take blood pressure medicines, ask a pharmacist before using sumac supplements. No source read describes an interaction; this is a cautious inference.
Blood fats (cholesterol and triglycerides)
Not enough evidenceResults disagree. A 2018 pooling of three trials found no significant change in cholesterol or triglycerides and said no firm conclusion was possible. A 2026 pooling reported improved blood fat measures, and a small 2025 trial found higher HDL but no change in LDL or triglycerides.
3 studiesSumac powder, supplements or seed-extract capsules.
Studies, doses and limits
What the trials found
2018: four trials in the review and three in the pooled analysis; no significant difference for total cholesterol, HDL, LDL or triglycerides; the authors say no definite conclusion can be made. 2026: 15 trials (917 people); the authors report significant improvement in lipid profile, with no numbers in the abstract. 2025: in 60 people with type 2 diabetes, HDL was higher and total cholesterol, LDL and triglycerides were not significantly different from control.
Results
Mixed and unclear. The favourable 2026 result cannot be checked from its abstract.
Effect sizes as reported
Not given in the abstracts read.
Why this rating
Insufficient: older pooling was null, the newer one gives no detail, and the trials were few and small.
Form and dose studied
Sumac powder, supplements or seed-extract capsules.
Who was studied
Adults; some with type 2 diabetes.
Limits
Trials used sumac powder, supplements or seed-extract capsules, not a sprinkle on food.
Why researchers looked
Sumac is described in some regions as a spice that lowers blood fats, so trials have tested it.
Traditional use
Sumac is used as a ground, dried, sour red spice on salads, meat, fish and rice, and in drinks. Long use as food is not proof that it treats any condition.
Proposed mechanism Unknown
Not established.
A proposed mechanism does not show that the effect happens in people.
If you take cholesterol medicines, ask a pharmacist before using sumac supplements.
Weight, BMI and waist size
Not enough evidenceA 2024 pooling of 15 trials found no effect of sumac on weight, body mass index or waist circumference. It reported a tiny change in waist-to-hip ratio (-0.01). Sumac is not a weight-loss food or supplement.
1 studiesSumac powder or supplements.
Studies, doses and limits
What the trials found
The 2024 meta-analysis of 15 randomised trials found no significant effects on weight, body mass index or waist circumference, and a waist-to-hip ratio change of -0.01 (95% CI -0.02 to -0.00, P=0.017).
Results
No effect on weight. A very small waist-to-hip change.
Effect sizes as reported
Waist-to-hip ratio -0.01 (95% CI -0.02 to -0.00).
Why this rating
No effect on the main weight measures, and the one small change is hard to interpret.
Form and dose studied
Sumac powder or supplements.
Who was studied
Adults.
Limits
Trials used sumac powder, supplements or seed-extract capsules, not a sprinkle on food.
Why researchers looked
Researchers checked body measures alongside blood sugar in the same trials.
Traditional use
Sumac is used as a ground, dried, sour red spice on salads, meat, fish and rice, and in drinks. Long use as food is not proof that it treats any condition.
Proposed mechanism Unknown
Not established.
A proposed mechanism does not show that the effect happens in people.
None specific.
Inflammation markers
Low certaintyA 2026 pooling of 15 trials found no significant effect of sumac supplements on inflammatory markers. This is a null result, reported so the page does not imply an anti-inflammatory benefit.
1 studiesSumac supplementation.
Studies, doses and limits
What the trials found
The 2026 meta-analysis (15 trials, 917 people, 4 to 12 weeks) found significant improvements in blood sugar and blood fat measures but no significant effect on inflammatory parameters.
Results
No clear effect on inflammation markers in people.
Effect sizes as reported
Not given in the abstract.
Why this rating
Low certainty of no effect: only the abstract was read and it has no numbers.
Form and dose studied
Sumac supplementation.
Who was studied
Adults.
Limits
Trials used sumac powder, supplements or seed-extract capsules, not a sprinkle on food. Cell and animal studies of sumac extracts report anti-inflammatory effects, but they do not predict results in people.
Why researchers looked
Sumac contains antioxidant plant compounds, so trials measured inflammation markers.
Traditional use
Sumac is used as a ground, dried, sour red spice on salads, meat, fish and rice, and in drinks. Long use as food is not proof that it treats any condition.
Proposed mechanism Unknown
Not established.
A proposed mechanism does not show that the effect happens in people.
None specific.
Antioxidant and other effects in cells and animals
Very low certaintyA 2021 review describes antioxidant, antibacterial, anti-diabetic and other effects of sumac extracts in the lab and in animals. This does not show a benefit in people, and extracts are not the same as sumac eaten as a spice.
1 studiesExtracts in lab and animal work.
Studies, doses and limits
Results
Lab and animal findings only.
Why this rating
Very low for people: cell and animal studies cannot show benefit in humans.
Form and dose studied
Extracts in lab and animal work.
Who was studied
Cells and animals.
Limits
Lab and animal research only. Extracts and doses used are not food amounts.
Why researchers looked
Sumac is rich in flavonoids, tannins, polyphenols and organic acids, so many lab studies exist.
Traditional use
Sumac is used as a ground, dried, sour red spice on salads, meat, fish and rice, and in drinks. Long use as food is not proof that it treats any condition.
Proposed mechanism Laboratory research
Reviews describe antioxidant activity of sumac extracts in cells and animals. Whether this happens in people who eat sumac is not shown.
A proposed mechanism does not show that the effect happens in people.
None specific.
Traditional uses (haemorrhoids, wounds, diarrhoea, ulcer, eye inflammation)
Not enough evidenceA 2021 review lists these traditional uses of sumac. The abstract gives no trial support for any of them, so no claim is made.
1 studiesNot applicable.
Studies, doses and limits
Results
Traditional use only.
Why this rating
Traditional use is not evidence of effect.
Limits
No trials read.
Why researchers looked
Traditional medicine in the Mediterranean region has used sumac for these problems.
Traditional use
The 2021 review says sumac has been used in traditional medicine for haemorrhoids, wound healing, diarrhoea, ulcer and eye inflammation.
Proposed mechanism Unknown
Not applicable.
A proposed mechanism does not show that the effect happens in people.
Do not put sumac preparations on wounds or eyes or use them for diarrhoea without medical advice.
Connections to the rest of health
How Sumac 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
A. Wellness goals
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Blood Sugar Balance | Mixed findings | Blood sugar markers (powder and supplements in trials): Pooled trials disagree. A 2021 pooling of 6 trials found no significant effect of sumac powder on any blood sugar measure. A 2024 pooling of 15 trials and a 2026 pooling of 15 trials reported improvements. All of this is powder or supplements, not a sprinkle of sumac on food. Sumac is not a treatment for diabetes. | 8 9 6 3 | |
| Blood Pressure Support | Low certainty | Blood pressure (diastolic): A 2024 pooling of 15 trials found diastolic blood pressure (the lower number) about 3 mmHg lower with sumac. That is a small change in a test number, not proof of fewer heart problems. The abstract does not report the upper number. | 9 |
B. Body systems
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Blood Sugar Support | Biological association | Mixed findings | Studied for: Blood sugar markers (powder and supplements in trials) | 8 9 6 3 |
| Cardiovascular System | Biological association | Low certainty | Studied for: Blood pressure (diastolic) Studied for: Blood fats (cholesterol and triglycerides) | 9 1 6 3 |
| Metabolism Weight | Biological association | Not enough evidence | Studied for: Weight, BMI and waist size | 9 |
| Immune System | Biological association | Low certainty | Studied for: Inflammation markers Studied for: Antioxidant and other effects in cells and animals | 6 2 |
| Digestive System | Biological association | Not enough evidence | Studied for: Traditional uses (haemorrhoids, wounds, diarrhoea, ulcer, eye inflammation) | 2 |
I. Biomarkers
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Fasting blood glucose | Biological association | Mixed findings | Measured in trials: mixed. A lab change is not the same as a health benefit. | 8 9 3 |
| HbA1c (average blood sugar over about 3 months) | Biological association | Low certainty | Measured in trials: mixed. A lab change is not the same as a health benefit. | 8 9 3 |
| Diastolic blood pressure | Biological association | Low certainty | Measured in trials: lowered. A lab change is not the same as a health benefit. | 9 |
| Blood lipids (total cholesterol, LDL, HDL, triglycerides) | Biological association | Not enough evidence | Measured in trials: mixed. A lab change is not the same as a health benefit. | 1 6 3 |
| Body weight, BMI and waist circumference | Biological association | Not enough evidence | Measured in trials: no-change. A lab change is not the same as a health benefit. | 9 |
| Inflammatory markers | Biological association | Low certainty | Measured in trials: no-change. A lab change is not the same as a health benefit. | 6 |
K. Biological pathways
L. Active compounds
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Flavonoids | Biological association | Lab | Named as a class in the review abstract; antioxidant activity in lab studies. Preparation or compound: Fruit |
2 |
| Tannins | Biological association | Lab | Named as a class in the review abstract. Preparation or compound: Fruit |
2 |
| Other polyphenols | Biological association | Lab | Named as a class in the review abstract. Preparation or compound: Fruit |
2 |
| Organic acids | Biological association | Lab | Named as a class in the review abstract. The sour taste of sumac is usually attributed to acids, but which acid and how much was not verified from a source read. Preparation or compound: Fruit |
2 |
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 26, 2026).
The evidence
The research centre for Sumac. 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 started from our existing sumac summary, re-read the study abstracts on PubMed, read the MedlinePlus, Frontiers in Allergy and PLOS ONE pages, checked plant names with GBIF and searched USDA FoodData Central. Items we could not verify are flagged in the research gaps.
Study library: every study we checked 15
| Study | Design | People | Product, dose, length | Result |
|---|---|---|---|---|
| Akbari-Fakhrabadi 2018 Effect of sumac (Rhus Coriaria) on blood lipids: A systematic review and meta-analysis. Complement Ther Med · PMID 30219474 · DOI |
Systematic review meta analysis |
4 randomised trials (3 in the pooled analysis) | Rhus coriaria (sumac) · vs Control groups |
The systematic review described positive changes in several lipid measures, but the meta-analysis of three studies found no significant difference for total cholesterol, HDL, LDL or triglycerides. The authors say no definite conclusion can be made. No significant pooled difference (Not given in the abstract) Methods, limits and fundingOutcomes: Total cholesterol, LDL, HDL, triglycerides, apolipoproteins Limitations: Very few trials and inconsistent results; authors call for better-designed trials. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Alsamri 2021 Pharmacological and Antioxidant Activities of Rhus coriaria L. (Sumac). Antioxidants (Basel) · PMID 33430013 · DOI |
Narrative review review |
Review of laboratory, animal and some other studies | Sumac extracts and fruit Mostly fruit Varies Varies · vs Varies |
The review says sumac has been used traditionally for haemorrhoids, wound healing, diarrhoea, ulcer and eye inflammation, describes antioxidant and other effects of extracts, and says toxicity studies show sumac is very safe to consume with little toxicity. Not applicable (Not applicable) Methods, limits and fundingOutcomes: Antioxidant, antibacterial, antidiabetic, cardioprotective, neuroprotective and anticancer effects (mostly in cells and animals) Limitations: A narrative review, mostly cells and animals. The "very safe" statement is the authors' summary; the abstract does not give the underlying studies, and it does not cover pregnancy, medicines or allergy. Funding and conflicts: Authors declare no conflict of interest. Read: abstract |
| Asgarirad 2025 Effectiveness of sumac seed (Rhus coriaria L.) capsules prepared from an aqueous extract in diabetic patients: A double-blind clinical trial study. Caspian J Intern Med · PMID 40786570 · DOI |
Controlled trial |
60 60 volunteers with type 2 diabetes |
Capsules made from an aqueous extract of sumac seed Seed 12 weeks · vs Control group |
Fasting blood sugar, HDL cholesterol and HbA1c differed significantly (p<0.01) in the sumac group compared with control and baseline. Total cholesterol, LDL and triglycerides did not differ significantly. Actual values not given in the abstract (Not given in the abstract) Methods, limits and fundingOutcomes: HbA1c, fasting blood sugar, total cholesterol, LDL, HDL, triglycerides Limitations: Small trial of a seed extract capsule, not the culinary fruit. Abstract gives no amounts or numbers and no trial registration. Authors conclude capsules could be used alongside usual drugs; that goes beyond what one small trial can show. Funding and conflicts: Authors declare no conflict of interest. Read: abstract |
| Bastiaan-Net 2019 IgE Cross-Reactivity of Cashew Nut Allergens. Int Arch Allergy Immunol · PMID 30368491 · DOI |
Laboratory research human-serum |
56 Blood serum from 56 children with suspected cashew nut allergy |
Blood tests of IgE antibodies against tree nuts, mango, pink peppercorn and sumac |
Of 56 children, 36 were positive for cashew on the test. Of these, 50% were sensitised to cashew only, 19% were also sensitised to other Anacardiaceae (the cashew plant family, which includes sumac) and 31% to tree nuts. Reactions were found in the lab to several species in the family. The authors say the clinical relevance is unknown. 19% co-sensitised to Anacardiaceae species (of 36 cashew-positive) (Not applicable) Methods, limits and fundingOutcomes: IgE sensitisation and cross-reactivity Limitations: Lab (in vitro) test, not people eating sumac. The abstract does not say how many reacted to sumac specifically. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Che 2017 Case reports of peanut-fenugreek and cashew-sumac cross-reactivity. J Allergy Clin Immunol Pract · PMID 28283164 · DOI |
Case report |
1 A 14-year-old with known cashew allergy |
Fattoush salad containing sumac spice |
This letter has no abstract on PubMed. A 2024 review (Frontiers in Allergy) describes it: a teenager with known cashew allergy developed anaphylaxis possibly to sumac spice after eating a fattoush salad. Not applicable (Not applicable) Methods, limits and fundingOutcomes: Anaphylaxis (a severe allergic reaction) Limitations: One case, described through a later review (the original letter was not read). The reaction was "possibly" to sumac; sumac was not confirmed as the cause. Funding and conflicts: Not stated. Read: abstract-only-no-abstract-available |
| Jafari 2026 Sumac (Rhus coriaria L.) and Human Metabolic Health: A Systematic Review and Meta-Analysis. Endocrinol Diabetes Metab · PMID 41329614 · DOI |
Systematic review meta analysis |
917 15 randomised trials, 917 participants, 4 to 12 weeks |
Sumac supplementation 4 to 12 weeks · vs Placebo |
The authors report significant improvements in blood sugar and blood fat measures and no significant effect on inflammatory markers or other risk factors. The abstract gives no numbers. Not given in the abstract (Not given in the abstract) Methods, limits and fundingOutcomes: Body measures, blood sugar, inflammation markers, blood fats Limitations: Only the abstract was read, so which glucose or lipid measures improved, by how much, and how reliable the trials were is unknown. Trials overlap with the 2024 review. Funding and conflicts: One author holds an editorial position at Systematic Reviews; no financial interests declared. Read: abstract |
| Lofgran 2026 Toxicodendron Toxicity. StatPearls · PMID 32491789 |
Review |
Clinical reference chapter on poison ivy, poison oak and poison sumac | Exposure to urushiol, the oil in Toxicodendron plants (poison ivy, poison oak, poison sumac) Plant oil on skin, by eating, or in smoke |
Urushiol, found in poison ivy, poison oak, poison sumac and other Toxicodendron species of the Anacardiaceae family, causes allergic contact dermatitis, an itchy blistering rash 12 to 72 hours after contact. Eating urushiol can cause a systemic reaction that can be life-threatening, and breathing smoke from burning plants can inflame the airways. Not applicable (Not applicable) Methods, limits and fundingOutcomes: Allergic contact dermatitis and other effects Limitations: This is about poison sumac, a different plant, not culinary sumac. It is included only so the two are not confused. Funding and conflicts: Authors declare no relevant financial relationships. Read: abstract |
| Mohit 2021 The effect of sumac (Rhus coriaria L.) supplementation on glycemic indices: A systematic review and meta-analysis of controlled clinical trials. Complement Ther Med · PMID 34365008 · DOI |
Systematic review meta analysis |
278 6 controlled trials, 278 participants |
Sumac powder supplementation · vs Control groups |
The authors report no significant effect of sumac powder on any blood sugar measure. Fasting glucose -7.08 mg/dl; HbA1c -0.48 %; HOMA-IR -0.97; insulin -2.94 (Hedges g). None significant by the authors. (Fasting glucose 95% CI -14.85 to 0.70 (P=0.07); HbA1c -1.01 to -0.04 (P=0.07); HOMA-IR -1.96 to 0.02 (P=0.05); insulin -6.67 to 0.80 (P=0.12)) Methods, limits and fundingOutcomes: Fasting blood glucose, HbA1c, HOMA-IR (insulin resistance), insulin Limitations: Few trials, high heterogeneity (I2 up to 83.8%). The HbA1c interval in the abstract does not match its P value, so only the authors' own conclusion (no significant effect) is relied on. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Taheri 2024 Effects of Sumac Consumption on Blood Pressure, Glycemic Indices, and Body Composition in Adults: A GRADE-assessed Systematic Review and Dose-response Meta-analysis. Diabetes Metab Syndr · PMID 39316955 · DOI |
Systematic review meta analysis |
15 randomised controlled trials in adults | Sumac consumption (powder or supplement; forms not detailed in the abstract) · vs Control groups |
Sumac lowered diastolic pressure, fasting glucose, insulin, HbA1c, HOMA-IR and waist-to-hip ratio. No significant effect on weight, BMI or waist circumference. The abstract does not report a systolic pressure result. Diastolic BP -2.88 mmHg; fasting glucose -5.15 mg/dL; insulin -1.95 uIU/ml; HbA1c -0.48 %; HOMA-IR -0.71; waist-to-hip ratio -0.01 (DBP -4.22 to -1.54; fasting glucose -8.73 to -1.57; HbA1c -0.84 to -0.12; HOMA-IR -1.14 to -0.27; WHR -0.02 to -0.00 (P=0.017)) Methods, limits and fundingOutcomes: Blood pressure, fasting glucose, insulin, HbA1c, HOMA-IR, weight, BMI, waist circumference, waist-to-hip ratio Limitations: Small trials of mixed quality; the abstract gives no certainty rating or dose details. The authors say higher doses or longer duration looked more promising for glucose, HOMA-IR and waist-to-hip ratio. Funding and conflicts: Authors declare no competing interests. Read: abstract |
| s-frontiers-anaphylaxis-2024 Frontiers in Allergy 2024: Rare causes of pediatric anaphylaxis due to obscure allergens · Source |
Narrative review |
Methods, limits and fundingRead: full-text | ||
| s-gbif-rhus-coriaria GBIF Backbone: Rhus coriaria L. (usageKey 3190563) · Source |
Reference database n/a |
Methods, limits and fundingRead: full-text | ||
| s-gbif-toxicodendron-vernix GBIF Backbone: Toxicodendron vernix (L.) Kuntze (usageKey 3190626) · Source |
Reference database n/a |
Methods, limits and fundingRead: full-text | ||
| s-medlineplus-poison-ivy MedlinePlus: Poison Ivy, Oak, and Sumac · Source |
Health agency n/a |
Methods, limits and fundingRead: full-text | ||
| s-plos-heavy-metals-2024 PLOS ONE 2024: Impact of source, packaging and presence of food safety management system on heavy metals levels in spices and herbs (Moussa et al.) · Source |
Lab analysis n/a |
Methods, limits and fundingRead: full-text | ||
| s-usda-fdc-sumac-search USDA FoodData Central: search for "sumac" · Source |
Database record n/a |
Methods, limits and fundingRead: search-result-only |
What we do not know yet
- No trial of sumac used as a seasoning on food was found for blood sugar, blood pressure or blood fats.
- The 2026 pooling and the 2025 trial gave no numbers in their abstracts, and the pooled reviews share many of the same trials.
- No source read gives advice for pregnancy, breastfeeding, children or medicines, and no regulator statement for culinary sumac was found.
- How common sumac allergy is, and how often cashew-allergic people react to it, is not known; the case report was read only through a later review.
- Nutrient numbers, other Rhus species, and oxalate, FODMAP and histamine content were not researched.
How new research is added
New studies are found by a saved PubMed search and placed in a review queue before the page changes.
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".
Metabolic 2
HbA1c (average blood sugar over about 3 months)
Mixed results in trials
A blood test showing average blood sugar over the past two to three months.
Low certaintyResults and what it means
Why it was measured
Used to follow long-term blood sugar control in diabetes.
Statistical vs. clinical meaning
A possible small change in supplement trials; the 2021 pooling reported no significant HbA1c effect.
Safety implication
None specific.
Body weight, BMI and waist circumference
No clear change in trials
Basic body measures.
Not enough evidenceResults and what it means
Why it was measured
Used to follow weight change.
Statistical vs. clinical meaning
No evidence sumac changes weight.
Safety implication
None specific.
| Study | Result | People | Product |
|---|---|---|---|
| 9 | No significant effects on weight, BMI or waist circumference; waist-to-hip ratio -0.01 (95% CI -0.02 to -0.00) | 15 randomised trials in adults | Sumac consumption (powder or supplements) |
Other 4
Fasting blood glucose
Mixed results in trials
Blood sugar measured after not eating overnight.
Mixed findingsResults and what it means
Why it was measured
A basic marker of blood sugar control.
Statistical vs. clinical meaning
A small possible drop in a test number; the two pooled reviews disagree.
Safety implication
None specific; ask a pharmacist if you take diabetes medicines.
Diastolic blood pressure
Lowered in trials
The lower of the two blood pressure numbers.
Low certaintyResults and what it means
Why it was measured
High blood pressure raises the risk of heart disease and stroke.
Statistical vs. clinical meaning
A small change in a test number, not proof of fewer heart problems.
Safety implication
Ask a pharmacist if you take blood pressure medicines.
| Study | Result | People | Product |
|---|---|---|---|
| 9 | -2.88 mmHg (95% CI -4.22 to -1.54), P=0.001 | 15 randomised trials in adults | Sumac consumption (powder or supplements) |
Blood lipids (total cholesterol, LDL, HDL, triglycerides)
Mixed results in trials
Fats in the blood, including LDL ("bad") and HDL ("good") cholesterol.
Not enough evidenceResults and what it means
Why it was measured
High LDL and triglycerides raise heart disease risk.
Statistical vs. clinical meaning
Results disagree and the newest pooling gives no detail.
Safety implication
None specific.
| Study | Result | People | Product |
|---|---|---|---|
| 1 | No significant pooled difference for total cholesterol, HDL, LDL or triglycerides (3 studies) | Adults in randomised trials | Rhus coriaria |
| 3 | HDL differed from control (p<0.01); total cholesterol, LDL and triglycerides did not | 60 people with type 2 diabetes | Capsules of aqueous sumac seed extract, 12 weeks |
Inflammatory markers
No clear change in trials
Blood tests that rise when the body has inflammation.
Low certaintyResults and what it means
Why it was measured
Used as general signs of inflammation.
Statistical vs. clinical meaning
Null result; no anti-inflammatory benefit shown.
Safety implication
None specific.
| Study | Result | People | Product |
|---|---|---|---|
| 6 | No significant effects on inflammatory parameters; no numbers in the abstract | 15 randomised trials, 917 people | Sumac supplementation, 4 to 12 weeks |
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 4
- Poison sumac is a different plant and is dangerous. Culinary sumac is Rhus coriaria.. The spice comes from the dried red fruit of Rhus coriaria. "Poison sumac" is Toxicodendron vernix, a different plant in the same family (Anacardiaceae). Its oily sap causes a blistering rash in most people, and eating it or breathing smoke from burning it can be serious. This page cannot help you identify plants. Do not gather wild "sumac" to eat; buy the spice from a food shop. Authoritative guidance 13 7 12 11
- Cashew allergy: sumac is in the same plant family. Sumac and cashew are both Anacardiaceae. A lab study of blood from 56 children with suspected cashew allergy found signs of reacting to several plants in this family, and one case report describes a teenager with cashew allergy who had anaphylaxis possibly to sumac. The clinical importance is unknown, but if you have a cashew allergy, ask an allergist before eating sumac. Case report 4 5 10
- Culinary amounts versus concentrated supplements. Most safety statements read are about sumac as a food. The trials used powders, supplements or seed-extract capsules. No source read describes safe amounts of concentrated products, and none gives medicine interactions, pregnancy or breastfeeding advice. Ask a pharmacist or doctor before using supplements, especially with diabetes or blood pressure medicines. Gap 2 9
- Lead in some spice samples. A 2024 study of herbs and spices sold in Lebanon found 25% to 33% of black pepper, sumac and dried mint samples over the Codex lead limit. It is one country and one study, but it is a reason to buy from a reputable seller. Other 14
Side effects 2
| Effect | How often | Severity and recovery | Evidence |
|---|---|---|---|
| Allergic reactions, including a reported severe reaction (anaphylaxis) in a teenager with cashew allergy after a salad with sumac, possibly caused by the sumac One case, read through a 2024 review (the letter has no abstract). The lab study of 56 children is not people eating sumac. No source says how common sumac allergy is. | Not established | Severe in the one case reported Not stated | Case report 5 10 4 |
| No adverse effects were described in the trial abstracts read The abstracts do not report side effects, so the absence of reports is not proof of safety. The 2021 review authors call sumac very safe to consume with little toxicity (their own summary). | Not established | not stated Not stated | Insufficient 8 9 6 3 |
Liver
No liver injury from sumac was found in the sources read. A liver-safety source such as LiverTox was not searched for this food page.
How often. No frequency was found.
Monitoring. No agency monitoring advice was found.
This is a safety connection. It is not evidence that Sumac supports liver health.
Medicines and supplements 2
| With | Why it matters | Importance | Evidence | What to do |
|---|---|---|---|---|
| Diabetes medicines (insulin, tablets) prescription | Some pooled trials found lower blood sugar markers with sumac powder or supplements. If true, an extra effect on blood sugar is plausible. No source read describes an interaction. | Unknown. This is a cautious inference from trial results, not a documented interaction. | Pharmacological theory Not enough evidence 9 3 | If you take diabetes medicines and want to use sumac supplements or extracts, ask a pharmacist. Culinary amounts on food were not studied for this. |
| Blood pressure medicines prescription | A pooled analysis found a small drop in diastolic pressure with sumac supplements. No source read describes an interaction. | Unknown. Cautious inference only. | Pharmacological theory Not enough evidence 9 | Ask a pharmacist before using sumac supplements if you take blood pressure medicines. |
Who should check first 5
| Situation | Advice | Evidence |
|---|---|---|
| Cashew allergy | Ask an allergist before eating sumac. A lab study and one case report suggest cross-reaction is possible; how often it matters is unknown. | Case report 4 5 |
| Known allergy to sumac | Avoid it. Call emergency services for trouble breathing or swelling of the face or throat. | Case report 5 |
| Mistaking poison sumac for edible sumac | Never forage wild sumac to eat. Poison sumac sap causes a blistering rash and eating or burning the plant can be serious. Buy the spice from a food shop. | Authoritative guidance 13 7 |
| Taking diabetes or blood pressure medicines and wanting supplements | Ask a pharmacist before using sumac supplements or extracts. | Pharmacological theory 9 |
| Pregnancy, breastfeeding and young children | No source read gives advice for sumac. Culinary use in food is common in the regions where it is grown, but safety of concentrated products is unknown. Ask a doctor. | Gap |
Overdose, product quality and regulators
Summary. The 2021 review authors say toxicity studies show sumac is very safe to consume and has little toxicity (their summary; the underlying studies were not read). The serious toxic plant to know about is poison sumac, which is a different species.
Animal. Summarised only in the 2021 review abstract.
Human doses studied. Trials of 4 to 12 weeks used powder or supplements; amounts were not in the abstracts read.
Overdose response. Not found.
Genotoxicity. Not researched.
Toxic or hazardous parts. Culinary sumac: none identified in the sources read. Poison sumac (Toxicodendron vernix): all parts contain urushiol, the irritant oil (MedlinePlus: root, stems, leaves and fruit).
Spices can carry heavy metals. Some ground sumac is sold mixed with salt.
Lead. In a 2024 Lebanon study of 96 spice and herb samples, 20% were over the Codex lead limit overall; for black pepper, sumac and dried mint the share over the limit ranged from 25% to 33%. Unpackaged samples had the highest rates of unacceptable lead. A sumac-only figure was not given. 14
Added salt. One US ground sumac product in the USDA branded food database lists sumac berries and salt as ingredients. Check the label if you limit salt. 15
| Body | Action | Date |
|---|---|---|
| MedlinePlus (US National Library of Medicine) (United States) | Poison Ivy, Oak, and Sumac page: the oily sap of poison ivy, oak and sumac causes a blistering skin rash; burning the plants can carry sap into the eyes, nose, throat and lungs source | 2026-10-26 |
When to get medical help
- Trouble breathing, swelling of the lips, face or throat, widespread hives or collapse after eating sumac (call emergency services)
- A spreading blistering rash, swelling around the eyes, or trouble breathing after touching or burning a wild plant you thought was sumac
- Any illness after eating a wild plant you are not sure about: contact Poison Control or emergency services
Stop using the product 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
What is sumac?
Is sumac the same as poison sumac?
Does sumac lower blood sugar?
Does sumac lower blood pressure?
A 2024 pooling of 15 trials found diastolic pressure about 3 mmHg lower (2.88 mmHg). That is a small change in a test number, and the abstract did not report the upper number.
Does sumac lower cholesterol?
Can sumac help with weight loss?
No effect was found. A 2024 pooling of 15 trials found no significant change in weight, BMI or waist circumference.
Is sumac anti-inflammatory?
Can I eat sumac if I am allergic to cashews?
Is sumac safe in pregnancy or for children?
We did not find advice for sumac in pregnancy, breastfeeding or young children in the sources read. Ask a doctor, especially about supplements or extracts.
Does sumac interact with medicines?
Does sumac contain lead?
Some spices do. In a 2024 study of spices sold in Lebanon, 25% to 33% of black pepper, sumac and dried mint samples were over the Codex lead limit. A sumac-only figure was not given. Buy from a reputable seller.
Does ground sumac contain salt?
Some does. One US product in the USDA database lists sumac berries and salt as ingredients. Check the label if you limit salt.
Explore by health goal
Editorial transparency
- Written by
- AlternativeMed editorial team. Research compiled with AI assistance, then checked against the sources listed.
- Medical review
- None. This page has not been reviewed by a physician or pharmacist.
- First published
- 2026-10-26
- Last substantive update
- 2026-10-26
- How we research
- We started from our existing sumac summary, re-read the study abstracts on PubMed, read the MedlinePlus, Frontiers in Allergy and PLOS ONE pages, checked plant names with GBIF and searched USDA FoodData Central. Items we could not verify are flagged in the research gaps.
- 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.
Sources 15
Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.
- Akbari-Fakhrabadi M, Heshmati J, Sepidarkish M, et al.. Effect of sumac (Rhus Coriaria) on blood lipids: A systematic review and meta-analysis.. Complement Ther Med. 2018. PMID 30219474. DOI 10.1016/j.ctim.2018.07.001. (abstract)
- Alsamri H, Athamneh K, Pintus G, et al.. Pharmacological and Antioxidant Activities of Rhus coriaria L. (Sumac).. Antioxidants (Basel). 2021. PMID 33430013. DOI 10.3390/antiox10010073. (abstract)
- Asgarirad H, Mahjoub S, Yadollahi M, et al.. Effectiveness of sumac seed (Rhus coriaria L.) capsules prepared from an aqueous extract in diabetic patients: A double-blind clinical trial study.. Caspian J Intern Med. 2025. PMID 40786570. DOI 10.22088/cjim.16.3.417. (abstract)
- Bastiaan-Net S, Reitsma M, Cordewener JHG, et al.. IgE Cross-Reactivity of Cashew Nut Allergens.. Int Arch Allergy Immunol. 2019. PMID 30368491. DOI 10.1159/000493100. (abstract)
- Che CT, Douglas L, Liem J.. Case reports of peanut-fenugreek and cashew-sumac cross-reactivity.. J Allergy Clin Immunol Pract. 2017. PMID 28283164. DOI 10.1016/j.jaip.2016.12.024. (abstract-only-no-abstract-available)
- Jafari A, ParsiNezhad B, AhmadianMoghaddam M, et al.. Sumac (Rhus coriaria L.) and Human Metabolic Health: A Systematic Review and Meta-Analysis.. Endocrinol Diabetes Metab. 2026. PMID 41329614. DOI 10.1002/edm2.70135. (abstract)
- Lofgran T, Mahabal GD, Schaffer DH.. Toxicodendron Toxicity.. StatPearls. 2026. PMID 32491789. (abstract)
- Mohit M, Nouri M, Samadi M, et al.. The effect of sumac (Rhus coriaria L.) supplementation on glycemic indices: A systematic review and meta-analysis of controlled clinical trials.. Complement Ther Med. 2021. PMID 34365008. DOI 10.1016/j.ctim.2021.102766. (abstract)
- Taheri S, Sohrabi Z, Bahari H, et al.. Effects of Sumac Consumption on Blood Pressure, Glycemic Indices, and Body Composition in Adults: A GRADE-assessed Systematic Review and Dose-response Meta-analysis.. Diabetes Metab Syndr. 2024. PMID 39316955. DOI 10.1016/j.dsx.2024.103122. (abstract)
- . Frontiers in Allergy 2024: Rare causes of pediatric anaphylaxis due to obscure allergens. . . (full-text)
- . GBIF Backbone: Rhus coriaria L. (usageKey 3190563). . . (full-text)
- . GBIF Backbone: Toxicodendron vernix (L.) Kuntze (usageKey 3190626). . . (full-text)
- . MedlinePlus: Poison Ivy, Oak, and Sumac. . . (full-text)
- . PLOS ONE 2024: Impact of source, packaging and presence of food safety management system on heavy metals levels in spices and herbs (Moussa et al.). . . (full-text)
- . USDA FoodData Central: search for "sumac". . . (search-result-only)
Where to buy
Check the label first. Whatever you buy, look for these:
- Whole or ground: whole spices keep their flavor longer
- The origin and a packed-on or best-by date for freshness
- Organic or non-irradiated labeling if that matters to you
- A resealable, airtight container
Talk to a pharmacist or doctor before you start any supplement, especially if you take medicines. See the Safety tab for interactions.
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