Pu-erh: the brewed tea, a pressed cake and loose leaf.

Pu-erh Tea

Camellia sinensis var. assamica · also called Pu'er tea, puer tea, dark tea, post-fermented tea. Not the same as black tea or pu-erh extract.

Pu-erh is a dark tea from Yunnan, China, made from tea leaves that are fermented by microbes and often aged. People drink it for weight, cholesterol and digestion. Research is thin: no trial of the drink itself was found, and the one small trial used an extract. It has caffeine, and aged tea can carry mould-related contaminants, though tested samples were mostly within limits.

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 Pu-erh Tea

Pu-erh is a fermented, often aged tea from Yunnan, China. Research on it is thin: one small extract trial, observational data on dark tea, and animal and lab studies. It has caffeine like other teas. Tested samples were mostly within official limits for mould toxins, pesticides and metals, but quality and storage matter.

What it is

A 2022 review describes pu-erh as post-fermented, sun-dried leaves of Camellia sinensis var. assamica, native to Yunnan, China. It belongs to dark tea, one of six major teas in China. Microbes such as fungi change its colour, aroma, taste and chemistry during pile fermentation and aging. Raw and ripened pu-erh differ in chemistry and microbes.

The tea contains caffeine, gallic acid and polyphenols, and a dark pigment called theabrownin.

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Tea, cake or extract?

Pu-erh is sold as loose leaf, pressed cakes and bricks, tea bags, and as water extracts or capsules. The only human weight trial used a water extract in barley tea, not a cup of tea, and the pigment results come from mice. Do not carry a result from one form to another. No safety study of pu-erh capsules was found.

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What the research shows

The one human pu-erh trial was small (36 adults) and used an extract. Reviewers say the human evidence is limited. A pooled review of green and black tea trials found no effect on cholesterol or blood pressure; pu-erh was not in it. A trial of Liupao tea, another post-fermented tea, saw LDL fall in four groups but had no no-tea group.

A cohort of people with prediabetes linked dark tea drinking with less progression to diabetes, which shows a link and not a cause. Animal studies point to antioxidant and cholesterol effects through gut microbes. These do not show an effect in people.

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Mould, storage and contaminants

Mycotoxins: a 20-sample study found tea mycotoxins well below limits, and a 120-sample survey of post-fermented tea found low fumonisin exposure. A 2026 review of tea mycotoxins found black tea the most contaminated type; the abstract gives no pu-erh figure.

Metals: raw pu-erh from different storage years had metals below Chinese limits, and storage years did not change them. Mercury in Polish teas, including pu-erh, was below the EU standard.

Reviewers say contaminants relate to growing, processing and storage, and ask for better quality control.

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Regulators and status

No agency page specific to pu-erh was found. The caffeine limits above come from the NHS and FDA. The EMA and EFSA were not checked for pu-erh.

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At a glance

Traditional uses history, not proof

A 2022 review says pu-erh is a highly prized tea from Yunnan, China, made from post-fermented, sun-dried leaves of the tea plant.
The same review lists claimed antioxidant, laxative, cholesterol-lowering and weight-control effects, and says limited human trials hardly convince the claims.
A 2022 review says pu-erh belongs to dark tea, one of six major teas in China.

Studied for research

Body weight and body fat, very low
Cholesterol and blood pressure, insufficient
Blood sugar and diabetes risk, very low
Antioxidant effects, insufficient (animal studies only)
Gut microbes, insufficient

Main compounds

Caffeine
Gallic acid
Theabrownin (a dark pigment from fermentation)
Tea polyphenols

Common forms

Loose leaf, raw (sheng) or ripened (shu)
Pressed cake or brick
Tea bags
Water extracts and capsules (a different product, used in the one human trial)

Research links: NHS: foods to avoid in pregnancy (caffeine) · FDA: How much caffeine is too much · Review: chemical constituents and biological properties of pu-erh (abstract) · Pu-erh extract weight trial (abstract) · Review: fungi and safety control of pu-erh (abstract) · Mycotoxins and pesticides in stored pu-erh (abstract) · Research Library · Genes & Biomarkers Library

What it is and its history

Accepted scientific name: Camellia sinensis var. assamica
Naming authority: (J.W.Mast.) Kitam.
Synonyms: Camellia sinensis var. assamica (Royle ex Hook.) Steenis (a GBIF record of the same variety under a different authority)
Common names: Pu-erh tea (English); Pu'er tea (English); Puer tea (English); Black Chinese tea (English)
Family or group: Theaceae (the tea family)
Classification: Plantae > Ericales > Theaceae > Camellia > Camellia sinensis
Native range: A 2022 review says pu-erh tea is made from a variety of the tea plant native to Yunnan, China.
Habitat: Not checked.
What it looks like: Roots: Not applicable.; Stems: Not checked.; Leaves: The leaf is the part used; pu-erh is post-fermented, sun-dried leaf (Wang 2022).; Flowers: Not checked.; Fruit: Not checked.
Cultivation: Not checked.
Harvest and processing: Wang 2022 describes pu-erh as post-fermented sun-dried leaves. Xu 2022 describes pile fermentation and aging in which fungi and other microbes change colour, aroma, taste and chemistry. Raw and ripened pu-erh have different chemistry and microbes (Wang 2022).
Look-alikes and adulterants: Name: Other dark and post-fermented teas (for example Liupao tea); Note: Made by different microbes and methods; trial results for one do not apply to another.; Name: Black tea; Note: Fully oxidised tea; not the same as post-fermented pu-erh, though caffeine was similar in one lab study.
Sustainability and conservation: Not checked.

Photographs

A glass cup of deep reddish-brown pu-erh tea beside a pressed round tea cake and loose dark leaves on a wooden table — Pu-erh: the brewed tea, a pressed cake and loose leaf.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
Yunnan, China	Wang 2022 describes pu-erh as a highly prized commodity from Yunnan, with claimed antioxidant, laxative, cholesterol-lowering and other effects. The authors say limited human trials hardly convince the claimed efficiency.	p35337597
Chinese tea classification	Xu 2022 says pu-erh belongs to dark tea, one of six major teas in China, and is a post-fermented tea with complex microbial composition.	p36201379
Antioxidant belief	Yang 2022 calls the antioxidant effect of pu-erh a long-held conventional wisdom with limited supporting evidence.	p35564056
Ages and dates	No source read gives the age or origin date of pu-erh tea; older tales found online were not used.

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
Caffeine PubChem 2519	purine alkaloid	Leaf About 13 +/- 2.9 mg per 200 mL infusion in one lab study; depends on brewing.	Stimulant; counts toward daily caffeine. ^{31 2 29}	Human data
Gallic acid PubChem 370	phenolic acid	Leaf (high in the pu-erh extract used in one trial) Not given in the sources read.	The trial authors link it to anti-obesity effects seen in animals. ^{32 10}	Animal research
Theabrownin	dark pigment formed in fermentation	Fermented leaf The abstract calls it one of the most active and abundant pigments in pu-erh; no figure given.	Lowered cholesterol in mice via gut microbes and bile acids. ⁷	Animal research
L-theanine	amino acid	Leaf Measured in tea types in one lab study; the abstract gives its highest values for black and green tea and no pu-erh figure.	Not studied for pu-erh in the sources read. ²	Lab analysis

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
Gut microbes, bile acids and FXR-FGF15 signalling	FXR, FGF15	Theabrownin changed gut microbes with bile-salt hydrolase activity, raised conjugated bile acids in the gut, blocked the FXR-FGF15 signal, and led to more bile acids lost in stool and less liver cholesterol in mice. ⁷	Animal research
Starch-digesting enzymes	alpha-amylase, alpha-glucosidase	Pu-erh inhibited both enzymes in studies pooled by a systematic review, with high differences between studies linked to fermentation degree. These are enzyme tests, not trials in people. ²⁶	Laboratory research
Oxidative stress markers	MDA, SOD, GSH-Px	Pu-erh extracts shifted these markers in animals. ²⁷	Animal research
Microbial fermentation	n/a	Fungi and other microbes change colour, aroma, taste and bioactive compounds during pile fermentation and aging. ²⁵	Authoritative review

Absorption, metabolism and elimination

Absorption: Not covered in the sources read.
Distribution: Not covered.
Metabolism: A 2026 review says tea polyphenols are poorly absorbed and rapidly cleared, limiting what reaches the blood. Not specific to pu-erh.
Elimination: Not covered.
Bioavailability: Low systemic exposure to intact polyphenols across tea types (Hu 2026).

⁶

Isolated compounds versus whole extracts

A pu-erh water extract in barley tea (the only human trial) is not the same as a brewed cup, and the isolated pigment theabrownin tested in mice is not the same as the whole tea. Raw and ripened pu-erh also differ in chemistry and microbes. Do not carry a result from one form to another.

Nutritional composition

Pu-erh tea itself is not a source of nutrients in the sources read; it has caffeine and polyphenols.

5benefits and uses looked at

33studies and sources checked

Very low certaintybest evidence rating found

6lab markers tracked in trials

2 very low certainty3 not enough evidence

What is Pu-erh Tea good for?

The uses people ask about and how strong the human evidence is for each. For pu-erh the honest answer is that the drink has barely been tested in people.

Body weight and body fatVery low certaintyOne small trial of a pu-erh extract in barley tea (36 adults, 12 weeks) found lower weight and belly fat. It was not a trial of the brewed tea, and reviewers say limited human trials hardly convince the claims. Cholesterol and blood pressureNot enough evidenceNo pu-erh trial was found. Pooled green and black tea trials found no effect, a different dark tea (Liupao) lowered LDL in a trial with no no-tea group, and pu-erh's pigment lowered cholesterol in mice. Blood sugar and diabetes riskVery low certaintyIn 2,662 Chinese adults with prediabetes, dark tea drinkers were less likely to progress to type 2 diabetes, but pu-erh was not separated and this cannot show cause. Pu-erh slowed starch-digesting enzymes in lab work. Antioxidant effectsNot enough evidenceA review of animal studies found changes in oxidative-stress markers. The authors call the antioxidant claim long-held with limited supporting evidence. No human trial was found. Gut microbes and digestionNot enough evidenceMouse studies and one trial of another dark tea show shifts in gut microbes. No trial shows pu-erh improves digestion.

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.

Body weight and body fat

Very low certainty

One small trial of a pu-erh water extract (not brewed tea) found lower weight, waist size and belly fat over 12 weeks. No trial of the tea as a drink was found. Reviewers say the human trials are too few to prove the claim.

3 studiesPu-erh water extract added to powdered barley tea. Not the same as br…

Studies, doses and limits

What the trials found

Kubota 2011: 36 pre-obese Japanese adults (BMI over 25 and under 30) took barley tea with or without a pu-erh water extract before each of three daily meals for 12 weeks, then were followed for 4 weeks. A 2022 review of pu-erh says limited human trials hardly convince the claimed effects, and a 2026 review says the metabolic effects of post-fermented teas are promising but less consistently tested in adequately powered trials.

Results

In the extract group body weight and BMI fell, and differed from placebo only from week 8. Waist size showed a similar trend. CT scans showed less visceral fat area at 12 weeks (P under .05). Blood tests showed no significant differences, and no side effects were reported.

Effect sizes as reported

The abstract gives no mean differences. The authors published an erratum in 2012 that was not read.

Why this rating

One small randomised trial (36 people) of an extract in barley tea, not of the tea drink. Funding not stated in the abstract and an erratum exists.

Form and dose studied

Pu-erh water extract added to powdered barley tea. Not the same as brewed leaf.

Who was studied

Pre-obese Japanese adults.

Limits

Tiny sample, extract not drink, 12 weeks, one trial, no replication found.

Why researchers looked

Pu-erh is often sold as a slimming tea, and animal studies reported anti-obesity effects of its gallic acid.

Traditional use

Not described in the sources read.

Proposed mechanism Hypothesis

The trial authors point to gallic acid in the extract, based on animal work. Reviews say most weight and appetite pathways rest on cell and rodent studies.

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

Pu-erh tea contains caffeine, and aged tea can carry mould-related contaminants. See the Safety tab.

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Cholesterol and blood pressure

Not enough evidence

No trial of pu-erh tea for cholesterol or blood pressure was found. A large review of green and black tea trials found no effect, a trial of a different post-fermented tea (Liupao) saw LDL fall, and pu-erh's pigment lowered cholesterol in mice.

3 studiesLiupao tea leaf infusion (trial) and isolated theabrownin (mice). Nei…

Studies, doses and limits

What the trials found

Igho-Osagie 2020 pooled 14 trials (798 people, 4 to 24 weeks) of green or black tea and found no significant change in blood pressure or cholesterol; pu-erh was not among the teas. Wang 2025 gave 71 adults with metabolic syndrome Liupao tea (another post-fermented dark tea, from Guangxi) aged 1, 4, 7 or 10 years for 90 days. There was no no-tea group; groups were compared by tea age.

Results

Liupao trial: LDL cholesterol fell significantly in all four aged groups, and blood pressure fell in the 10-year-aged group. Differences between groups were not significant. Green/black tea pooled analysis: no significant change in SBP, DBP, total, LDL, HDL or triglycerides.

Effect sizes as reported

No pooled numbers for pu-erh. The abstracts give P values but not mean changes for the Liupao trial.

Why this rating

No human trial of pu-erh for this outcome. The nearest trial used a different tea and had no no-tea control; the pigment result is from mice.

Form and dose studied

Liupao tea leaf infusion (trial) and isolated theabrownin (mice). Neither is pu-erh tea as a drink.

Who was studied

Adults with metabolic syndrome (Liupao trial); healthy and at-risk adults (green/black tea review); mice.

Limits

Different tea, no control group, mouse mechanism, short trials.

Why researchers looked

Pu-erh is widely said to lower cholesterol, and theabrownin, its main dark pigment, lowers cholesterol in mice.

Traditional use

Not described in the sources read.

Proposed mechanism Animal research

In mice, theabrownin changed gut microbes, raised bile acids in the gut and lowered liver cholesterol. The authors report that it also altered gut microbes in humans, but the abstract does not give the human data.

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

Pu-erh tea contains caffeine, and aged tea can carry mould-related contaminants. See the Safety tab.

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Blood sugar and diabetes risk

Very low certainty

People with prediabetes who drank dark tea were less likely to move on to type 2 diabetes in one Chinese study, but pu-erh was not separated out and this cannot show cause. Lab work shows pu-erh slows starch-digesting enzymes. No trial of the tea in people with diabetes was found.

2 studiesSelf-reported dark tea drinking (cohort); pu-erh extracts in enzyme t…

Studies, doses and limits

What the trials found

Li 2025 followed 2,662 Chinese adults with prediabetes for about 3 years and asked about tea type and frequency at the start. Dark tea consumers were less likely than non-drinkers to progress to type 2 diabetes (odds ratio 0.28, 95% CI 0.11 to 0.72). The abstract does not break out pu-erh within dark tea.

Results

Dark tea: OR 0.28 (0.11 to 0.72) for progression to type 2 diabetes. Green tea: OR 0.73 (0.59 to 0.90) for returning to normal blood sugar.

Effect sizes as reported

Odds ratio 0.28 for dark tea; the confidence interval is wide.

Why this rating

One observational cohort that lumps pu-erh with other dark teas, plus enzyme work in the lab. No randomised trial.

Form and dose studied

Self-reported dark tea drinking (cohort); pu-erh extracts in enzyme tests.

Who was studied

Chinese adults with prediabetes.

Limits

Observational (habits and other factors may explain it), dark tea type not specified, enzyme results do not show an effect in people.

Why researchers looked

Pu-erh has been presumed to lower blood sugar by blocking enzymes that break down starch.

Traditional use

Not described in the sources read.

Proposed mechanism Lab only

A systematic review of 6 studies (alpha-glucosidase) and 7 studies (alpha-amylase) found pu-erh significantly slowed both enzymes, with high heterogeneity that the authors link to different degrees of fermentation.

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

Pu-erh tea contains caffeine, and aged tea can carry mould-related contaminants. See the Safety tab. If you take diabetes medicines, ask your pharmacist before changing how much tea you drink.

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Antioxidant effects

Not enough evidence

Pu-erh is long said to be an antioxidant tea. A review of animal studies found it shifted oxidative-stress markers in animals, but the authors themselves call the claim long-held with limited supporting evidence. No human trial was found.

2 studiesPu-erh tea extracts given to animals.

Studies, doses and limits

What the trials found

None found. Yang 2022 pooled animal studies only.

Results

Pooled animal studies: serum MDA lower (SMD -4.19, 95% CI -5.22 to -3.15), SOD higher (SMD 2.41, 1.61 to 3.20), GSH-Px higher (SMD 4.23, 3.10 to 5.36). Heterogeneity was very high (I2 above 90 percent).

Effect sizes as reported

Very large animal effects with I2 above 90 percent; not applicable to people.

Why this rating

Animal studies only, very high heterogeneity, no human data.

Form and dose studied

Pu-erh tea extracts given to animals.

Who was studied

Animals.

Limits

No human trial; blood markers are not health outcomes.

Why researchers looked

Antioxidant action is one of the most common claims made for pu-erh.

Traditional use

The review authors describe the antioxidant effect as long-held conventional wisdom.

Proposed mechanism Animal research

Pu-erh extracts changed markers of oxidative stress in animals (lower MDA, higher SOD and GSH-Px). These markers in blood do not show a health benefit.

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

Pu-erh tea contains caffeine, and aged tea can carry mould-related contaminants. See the Safety tab.

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Gut microbes and digestion

Not enough evidence

Pu-erh and other dark teas change gut microbes in mice, and a small trial of another dark tea saw a shift in one microbe ratio. No trial shows pu-erh improves digestion or gut health in people.

2 studiesLiupao tea (trial); isolated theabrownin (mice).

Studies, doses and limits

What the trials found

Wang 2025 (Liupao tea, a different post-fermented tea) measured gut microbes in 71 adults with metabolic syndrome and saw a lower Firmicutes/Bacteroides ratio in the 10-year-aged group. No pu-erh trial of gut health was found.

Results

Firmicutes/Bacteroides ratio fell in one of four groups of a Liupao tea trial with no no-tea control. Mouse study: gut microbe and bile-acid changes with theabrownin.

Effect sizes as reported

No numbers in the abstracts.

Why this rating

Mouse work and a different tea in a trial without a no-tea group.

Form and dose studied

Liupao tea (trial); isolated theabrownin (mice).

Who was studied

Adults with metabolic syndrome (Liupao); mice.

Limits

Different tea; a microbe ratio is not a health outcome; no digestion symptoms measured in the abstracts.

Why researchers looked

Dark tea is fermented by microbes and its pigments reach the gut, where microbes change them.

Traditional use

Not described in the sources read.

Proposed mechanism Animal research

In mice, theabrownin from pu-erh changed gut microbes tied to bile-acid handling. Reviews say gut microbe changes and short-chain fatty acids are proposed routes for tea effects.

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

Live microbes were found in pu-erh brews (see the Safety tab).

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Connections to the rest of health

How Pu-erh Tea 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
Weight Management		Very low certainty	Body weight and body fat: One small trial of a pu-erh water extract (not brewed tea) found lower weight, waist size and belly fat over 12 weeks. No trial of the tea as a drink was found. Reviewers say the human trials are too few to prove the claim.	^{10 23 6}
Metabolic Health		Very low certainty	Body weight and body fat: One small trial of a pu-erh water extract (not brewed tea) found lower weight, waist size and belly fat over 12 weeks. No trial of the tea as a drink was found. Reviewers say the human trials are too few to prove the claim. Blood sugar and diabetes risk: People with prediabetes who drank dark tea were less likely to move on to type 2 diabetes in one Chinese study, but pu-erh was not separated out and this cannot show cause. Lab work shows pu-erh slows starch-digesting enzymes. No trial of the tea in people with diabetes was found.	^{10 23 6 12 26}
Cholesterol Balance		Not enough evidence	Cholesterol and blood pressure: No trial of pu-erh tea for cholesterol or blood pressure was found. A large review of green and black tea trials found no effect, a trial of a different post-fermented tea (Liupao) saw LDL fall, and pu-erh's pigment lowered cholesterol in mice.	^{9 24 7}
Heart Health		Not enough evidence	Cholesterol and blood pressure: No trial of pu-erh tea for cholesterol or blood pressure was found. A large review of green and black tea trials found no effect, a trial of a different post-fermented tea (Liupao) saw LDL fall, and pu-erh's pigment lowered cholesterol in mice.	^{9 24 7}
Blood Sugar Balance		Very low certainty	Blood sugar and diabetes risk: People with prediabetes who drank dark tea were less likely to move on to type 2 diabetes in one Chinese study, but pu-erh was not separated out and this cannot show cause. Lab work shows pu-erh slows starch-digesting enzymes. No trial of the tea in people with diabetes was found.	^{12 26}
Healthy Aging	Biological association	Not enough evidence	Antioxidant effects: Pu-erh is long said to be an antioxidant tea. A review of animal studies found it shifted oxidative-stress markers in animals, but the authors themselves call the claim long-held with limited supporting evidence. No human trial was found.	^{27 23}
Cellular Protection	Biological association	Not enough evidence	Antioxidant effects: Pu-erh is long said to be an antioxidant tea. A review of animal studies found it shifted oxidative-stress markers in animals, but the authors themselves call the claim long-held with limited supporting evidence. No human trial was found.	^{27 23}
Gut Health	Biological association	Not enough evidence	Gut microbes and digestion: Pu-erh and other dark teas change gut microbes in mice, and a small trial of another dark tea saw a shift in one microbe ratio. No trial shows pu-erh improves digestion or gut health in people.	^{24 7}
Microbiome Balance	Biological association	Not enough evidence	Gut microbes and digestion: Pu-erh and other dark teas change gut microbes in mice, and a small trial of another dark tea saw a shift in one microbe ratio. No trial shows pu-erh improves digestion or gut health in people.	^{24 7}

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Metabolism Weight	Biological association	Very low certainty	Studied for: Body weight and body fat Studied for: Blood sugar and diabetes risk	^{10 23 6 12 26}
Cardiovascular System	Biological association	Not enough evidence	Studied for: Cholesterol and blood pressure	^{9 24 7}
Longevity Aging	Biological association	Not enough evidence	Studied for: Antioxidant effects	^{27 23}
Gut Health	Biological association	Not enough evidence	Studied for: Gut microbes and digestion	^{24 7}

E. Health conditions

Connected to	Kind of connection	Evidence status	Context	Studies
Pregnancy	Contraindication	Low certainty	Caffeine limit; no pu-erh-specific study. Preparation or compound: Pu-erh (caffeine)	^{30 17}
Iron-deficiency anemia	Adverse effect or risk	Low certainty	Lowers iron absorption; pu-erh not tested. Preparation or compound: Tea polyphenols	⁸
Obesity		Very low certainty	One small extract trial. Preparation or compound: Pu-erh water extract	¹⁰

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
Body weight and BMI	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	¹⁰
Visceral (belly) fat area on CT	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	¹⁰
LDL cholesterol	Biological association	Not enough evidence	Measured in trials: mixed. A lab change is not the same as a health benefit.	^{9 24}
Progression from prediabetes to type 2 diabetes	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	¹²
Malondialdehyde (MDA), an oxidative stress marker	Biological association	Not enough evidence	Measured in trials: lowered. A lab change is not the same as a health benefit.	²⁷
Antioxidant enzymes SOD and GSH-Px	Biological association	Not enough evidence	Measured in trials: raised. A lab change is not the same as a health benefit.	²⁷

K. Biological pathways

Connected to	Kind of connection	Evidence status	Context	Studies
FXR-FGF15 bile acid signalling	Preliminary mechanism	Animal	Blocked by theabrownin in the gut of mice.	⁷

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Caffeine	Adverse effect or risk	Moderate certainty	Counts toward daily caffeine; lab figure close to black tea. Counts toward daily caffeine. Preparation or compound: Pu-erh tea	^{2 29 30}
Caffeine	Biological association	Human	Stimulant; counts toward daily caffeine. Preparation or compound: Leaf	^{31 2 29}
Gallic acid	Biological association	Animal	The trial authors link it to anti-obesity effects seen in animals. Preparation or compound: Leaf (high in the pu-erh extract used in one trial)	^{32 10}
Theabrownin	Biological association	Animal	Lowered cholesterol in mice via gut microbes and bile acids. Preparation or compound: Fermented leaf	⁷
L-theanine	Biological association	Lab analysis	Not studied for pu-erh in the sources read. Preparation or compound: Leaf	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 25, 2026).

Evidence at a glance: what changed in 6 lab markers

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

Metabolic11 Other31

The evidence

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

Evidence by outcome

Body weight and body fat 3 studies · 36 people in trials Very low certainty Cholesterol and blood pressure 3 studies · 71 people in trials Not enough evidence Blood sugar and diabetes risk 2 studies · 2,662 people in trials Very low certainty Antioxidant effects 2 studies Not enough evidence Gut microbes and digestion 2 studies · 71 people in trials Not enough evidence

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 the abstracts of about 30 sources, read the NHS and FDA pages, and checked the plant name in GBIF and two compounds in PubChem. Only abstracts were read for papers. Certainty ratings are the compiler's own reading. Funding was not stated in several abstracts, so industry links are not ruled out. No study is cited that we could not verify.

Study library: every study we checked 33

Design Research type Year from Search

Study	Design	People	Product, dose, length	Result
Arafa 2024 The Association between Antenatal Tea Drinking and Hypertensive Disorders of Pregnancy: A Systematic Review and Meta-Analysis Epidemiologia (Basel) · PMID 38804341 · DOI	Meta-analysis	Studies of antenatal tea drinking and hypertensive disorders of pregnancy	Tea drinking, highest versus lowest frequency tea n/a n/a · vs Lowest frequency	Highest tea drinking was linked with higher odds of hypertensive disorders (pooled OR 1.16, 95% CI 1.01 to 1.33). For (pre-)eclampsia alone the link was not significant (OR 1.28, 0.86 to 1.89). The authors advise against excessive tea in pregnancy but call for cohort studies by tea type and caffeine. OR 1.16 (1.01 to 1.33) Methods, limits and funding Outcomes: Hypertensive disorders of pregnancy Limitations: Observational; tea types not separated Funding and conflicts: No conflicts declared Read: abstract
Ayakdaş 2025 Determination of L-Theanine and Caffeine Contents in Tea Infusions with Different Fermentation Degrees and Brewing Conditions Using the Chromatographic Method Foods · PMID 40647065 · DOI	Lab analysis laboratory	Tea infusions of six types including pu-erh	Pu-erh, green, white, yellow, oolong and black tea infusions leaf n/a n/a · vs n/a	Pu-erh had about 13 +/- 2.9 mg of caffeine per 200 mL, comparable to black tea (14 +/- 1.0). Longer brewing raised caffeine and theanine in some teas; bag type changed caffeine in black tea. About 13 mg caffeine per 200 mL Methods, limits and funding Outcomes: Caffeine and L-theanine in the infusion Limitations: One laboratory; brewing conditions in the study differ from daily practice; other analyses give different figures Funding and conflicts: Authors declare no conflicts; funders had no role Read: abstract
Brodziak-Dopierała 2022 Analysis of Mercury Content in Various Types of Tea (Camellia sinensis) and Yerba Mate (Ilex paraguariensis) Int J Environ Res Public Health · PMID 35564885 · DOI	Food analysis laboratory	86 86 black, green, white, pu-erh teas and yerba mate from Poland	Teas incl. pu-erh leaf n/a n/a · vs n/a	Mean mercury was 2.47 micrograms per kg overall, below the EU standard, so no risk from mercury was found. Pu-erh ranked below yerba mate and green tea and above white and black tea in mercury. Below EU standard Methods, limits and funding Outcomes: Mercury Limitations: Poland only Funding and conflicts: No conflicts declared Read: abstract
Chau 2023 Simultaneous Determination of Pesticide Residues and Mycotoxins in Storage Pu-erh Tea Using Ultra-High-Performance Liquid Chromatography Coupled with Tandem Mass Spectrometry Molecules · PMID 37836726 · DOI	Food analysis laboratory	31 31 pu-erh tea samples (raw and ripened, various storage times)	Pu-erh tea leaf n/a Stored up to over 30 years · vs n/a	No pesticide residues detected. Mycotoxins were well below official limits. Aflatoxin B1, G1 and G2 were under 1 ppb in samples stored over 30 years. Below official limits Methods, limits and funding Outcomes: 31 pesticides and 6 mycotoxins Limitations: 31 samples only; one lab Funding and conflicts: No conflict of interest declared Read: abstract
Guennouni 2026 Prevalence of mycotoxin contamination in different types of tea: a systematic review and meta-analysis Mycotoxin Res · PMID 41627675 · DOI	Meta-analysis laboratory	21 studies of mycotoxins in black, green, dark, white and pu-erh tea	Tea of several types leaf n/a n/a · vs n/a	Black tea had the highest contamination rate (89.2 percent) followed by green tea (67.3 percent). Prevalence was higher before 2018 and lower in high-income countries. The abstract gives no pu-erh figure. Prevalence rates by tea type Methods, limits and funding Outcomes: Prevalence of mycotoxin contamination Limitations: Pu-erh rate not given in the abstract; wide confidence intervals Funding and conflicts: No competing interests declared Read: abstract
Hu 2026 Tea Bioactive Compounds in Obesity Prevention and Management: Processing-Dependent Composition, Molecular Mechanisms, Human Evidence, and Translational Challenges Int J Mol Sci · PMID 42653208 · DOI	Narrative review human and laboratory	Review of tea compounds in obesity (all tea types)	Tea of several types, including post-fermented tea leaf n/a n/a · vs n/a	Evidence is strongest for modest effects of green-tea catechin-caffeine preparations on energy metabolism and some body measures. For oolong and post-fermented teas the metabolic effects are called promising but less consistently tested in adequately powered human trials. The review says available clinical data do not support tea as a primary treatment for obesity. Many mechanisms rest on cell and rodent studies. Review; no pooled effect for pu-erh Methods, limits and funding Outcomes: Mechanisms, human evidence, safety Limitations: Narrative review, abstract read only Funding and conflicts: Not stated in the abstract Read: abstract
Huang 2019 Theabrownin from Pu-erh tea attenuates hypercholesterolemia via modulation of gut microbiota and bile acid metabolism Nat Commun · PMID 31672964 · DOI	Lab and animal mouse	Mice (and gut microbiota samples from humans, as the abstract states)	Theabrownin, a dark pigment of pu-erh tea isolated pigment n/a n/a · vs n/a	Theabrownin altered gut microbes, increased bile acids in the gut, blocked a gut signalling pathway (FXR-FGF15), and led to more bile acid made and lost in stool, less liver cholesterol and less fat production. The authors suggest this explains the cholesterol-lowering effect. Mechanism in mice Methods, limits and funding Outcomes: Gut microbes, bile acids, liver cholesterol Limitations: Isolated pigment in mice; the abstract does not give the human data; no tea drinking trial Funding and conflicts: No competing interests declared Read: abstract
Hurrell 1999 Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages Br J Nutr · PMID 10999016	Clinical trial	Adult volunteers given a bread meal	Black tea, cocoa, coffee and herb teas drink Different drinks per serving single meals · vs Water	Black tea cut iron absorption by 79 to 94 percent, peppermint tea 84 percent and camomile 47 percent. Drinks with 20 to 50 mg polyphenols per serving cut absorption by 50 to 70 percent. Pu-erh was not tested. Large reductions Methods, limits and funding Outcomes: Iron absorption Limitations: Single-meal trial; pu-erh not tested; 1999 Funding and conflicts: Not stated Read: abstract
Igho-Osagie 2020 Short-Term Tea Consumption Is Not Associated with a Reduction in Blood Lipids or Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials J Nutr · PMID 33188386 · DOI	Meta-analysis	798 14 randomised trials in healthy adults and adults with obesity, prediabetes, borderline high cholesterol or metabolic syndrome	Green tea or black tea (no pu-erh) leaf Differed 4 to 24 weeks (mean 7.4) · vs Placebo or control	No significant effect of tea on any outcome. Certainty of evidence was low to moderate because of small samples and low power. The authors call for longer, larger trials. No significant effect Methods, limits and funding Outcomes: Blood pressure, total, LDL, HDL cholesterol and triglycerides Limitations: Does not include pu-erh; short trials; low power Funding and conflicts: Not stated in the abstract Read: abstract
Kubota 2011 Improvements of mean body mass index and body weight in preobese and overweight Japanese adults with black Chinese tea (Pu-Erh) water extract Nutr Res · PMID 21745623 · DOI	Controlled trial	36 36 pre-obese Japanese adults, BMI over 25 and under 30 kg/m2	Pu-erh (black Chinese tea) water extract, high in gallic acid, in powdered barley tea extract of fermented leaf Taken before each of three daily meals (amount not reproduced here) 12 weeks plus 4 weeks follow-up · vs Powdered barley tea without the extract (placebo), double-blind	Body weight and BMI fell in the extract group, with differences from placebo only from week 8. Waist size showed a similar trend. Visceral fat area was smaller at 12 weeks (P under .05). Biochemical tests showed no significant differences. No adverse effects such as bloating were reported. Lower weight, BMI and visceral fat in an extract group; size not given in the abstract Methods, limits and funding Outcomes: Body weight, BMI, waist size, visceral fat on CT, blood tests, side effects Limitations: Small trial; extract in barley tea, not tea; erratum published in Nutr Res 2012 (not read); funding not stated in the abstract. Funding and conflicts: Not stated in the abstract Read: abstract
Li 2020 Comparison and Risk Assessment for Trace Heavy Metals in Raw Pu-erh Tea with Different Storage Years Biol Trace Elem Res · PMID 31625054 · DOI	Food analysis laboratory	Raw pu-erh samples of different storage years	Raw pu-erh tea leaf n/a Different storage years · vs n/a	Arsenic, chromium, cadmium, lead, copper, zinc, manganese and mercury were all below Chinese national limits; combined hazard index for adults was 0.221 (no health risk when consumed properly); storage years did not affect metal exposure. Below limits Methods, limits and funding Outcomes: Heavy metal content and hazard Limitations: Raw pu-erh only; Chinese limits Funding and conflicts: Not stated Read: abstract
Li 2025 The Impact of Tea Consumption on Prediabetes Regression and Progression: A Prospective Cohort Study Nutrients · PMID 40732991 · DOI	Cohort study	2662 2,662 Chinese adults with prediabetes followed for about 3 years	Self-reported tea type (green, black, dark, other) and frequency leaf Not measured About 3 years · vs Non-tea drinkers	Dark tea consumers were less likely than non-drinkers to progress to type 2 diabetes (OR 0.28, 95% CI 0.11 to 0.72, p=0.01). Green tea was linked to a smaller chance of returning to normal blood sugar (OR 0.73, 0.59 to 0.90). OR 0.28 for dark tea (0.11 to 0.72) Methods, limits and funding Outcomes: Progression to type 2 diabetes; regression to normal blood sugar Limitations: Observational; pu-erh not separated within dark tea; tea intake asked once at baseline Funding and conflicts: No conflict of interest declared Read: abstract
Luo 2022 Hot Tea Consumption and Esophageal Cancer Risk: A Meta-Analysis of Observational Studies Front Nutr · PMID 35479756 · DOI	Meta-analysis	23 reports, 5,050 cases and 10,609 controls	Hot tea drinking tea n/a n/a · vs Lower temperature	Hot tea was linked with higher odds of esophageal squamous cell carcinoma (OR 1.79; 95% CI 1.48 to 2.15) but not adenocarcinoma. OR 1.79 (1.48 to 2.15) Methods, limits and funding Outcomes: Esophageal cancer Limitations: Observational; pu-erh not separated Funding and conflicts: No conflicts declared Read: abstract
Malinowska 2008 Assessment of fluoride concentration and daily intake by human from tea and herbal infusions Food Chem Toxicol · PMID 18078704 · DOI	Food analysis laboratory	Commercial black, green, oolong, pu-erh and white teas and herbal infusions	Tea infusions infusion n/a 5, 10 and 30 minute brews · vs n/a	Brewing longer raised fluoride; black tea was highest. For five cups of black tea a day, adult and child intake reached 8.0 to 303 percent and 12 to 303 percent of the Polish safe intake. The authors say excess fluoride from tea can raise dental fluorosis risk in children and skeletal fluorosis with long exposure. The abstract gives no pu-erh figure. Black tea highest Methods, limits and funding Outcomes: Fluoride and estimated intake Limitations: Poland, 2008; no pu-erh figure Funding and conflicts: Not stated Read: abstract
Pandey 2023 Mycotoxins along the tea supply chain: A dark side of an ancient and high valued aromatic beverage Crit Rev Food Sci Nutr · PMID 35452322 · DOI	Narrative review laboratory	Review of mycotoxins along the tea supply chain	Tea including pu-erh leaf n/a n/a · vs n/a	Describes mycotoxin production by tea fungi under poor processing and hot humid conditions and says many studies have looked at aflatoxins and ochratoxins in black, green, pu-erh and herbal teas, with less data on others. Review Methods, limits and funding Outcomes: Prevalence, toxicity, detection Limitations: Narrative review; abstract only Funding and conflicts: Not stated Read: abstract
Qiu 2023 B-Type Fumonisins in Post-Fermented Tea: Occurrence and Consumer Dietary Exposure in Guangxi, China Toxins (Basel) · PMID 37755960 · DOI	Food analysis	120 120 post-fermented tea samples and a consumption survey in Guangxi, China	Post-fermented tea (pu-erh not named in the abstract) leaf n/a n/a · vs n/a	Fumonisins were found in 20 percent (24/120) at 2.14 to 18.28 micrograms per kg. Average consumption was 9.19 g a day and only 0.026 percent of the provisional maximum tolerable daily intake was reached. The authors say this is not a public health risk. Low exposure Methods, limits and funding Outcomes: B-type fumonisins and dietary exposure Limitations: Post-fermented tea in general, not pu-erh specifically; one region Funding and conflicts: No competing interest declared Read: abstract
Rohweder 2024 Caffeine intake during pregnancy and adverse outcomes: An integrative review Reprod Toxicol · PMID 38042437 · DOI	Narrative review	59 studies included from 16,192 screened, on caffeine in pregnancy	Caffeine from all sources n/a n/a n/a · vs n/a	Associations were found with pregnancy loss, low birth weight, cardiac and genital anomalies, higher body mass and neurodevelopment outcomes, often dose dependent. Some studies saw them below 200 mg a day. No association with prematurity was shown. No safe dose could be defined because studies differ. Associations, often dose dependent Methods, limits and funding Outcomes: Pregnancy loss, birth weight, malformations, child development Limitations: Integrative review of mixed observational studies; caffeine intake is hard to measure Funding and conflicts: No conflicts declared Read: abstract
Shao 2020 Fluoride in tea from Shandong Province, China and exposure assessment Food Addit Contam Part B Surveill · PMID 31905107 · DOI	Food analysis laboratory	170 170 tea samples from Shandong, China	Pu-erh, green, oolong and black teas leaf n/a n/a · vs n/a	Mean fluoride was highest in pu-erh (164 mg/kg) versus green 121, oolong 98.7 and black 96.8. 4.7 percent of all samples exceeded China's limit of 200 mg/kg. Estimated adult daily intake via tea was 0.655 to 1.07 mg, below the 3.5 mg tolerable value. Pu-erh highest of four Methods, limits and funding Outcomes: Fluoride and estimated intake Limitations: Shandong market samples only Funding and conflicts: Not stated Read: abstract
Szmagara 2022 Determination of fluoride content in teas and herbal products popular in Poland J Environ Health Sci Eng · PMID 36406606 · DOI	Food analysis laboratory	33 33 teas and herbal products on the Polish market	Black, green, white, Earl Grey and pu-erh infusions and herbal products infusion n/a Brew time varied up to 15 min · vs n/a	Ranking black > green > Earl Grey > pu-erh > white >>> herbal. Infusions were not high enough to risk fluorosis even at 15 minutes of brewing. Pu-erh mid-ranked Methods, limits and funding Outcomes: Fluoride Limitations: Poland only Funding and conflicts: No conflict of interest declared Read: abstract
Uhlig 2025 Viable and Heat-Resistant Microbiota with Probiotic Potential in Fermented and Non-Fermented Tea Leaves and Brews Microorganisms · PMID 40431137 · DOI	Laboratory laboratory	Four tea types, leaves and brews	Oolong and fermented teas including pu-erh leaf and brew n/a n/a · vs n/a	Pu-erh had the highest viable bacterial count. Two potentially pathogenic species (Staphylococcus epidermidis, Bacillus cereus) were identified among isolates. Live bacteria, including Heyndrickxia coagulans, were found in pu-erh after brewing at 90 C. Live bacteria survive brewing in the lab Methods, limits and funding Outcomes: Live microbes before and after brewing Limitations: Lab culture study; not an illness study Funding and conflicts: No conflicts declared Read: abstract
Wan 2025 Establishment of appropriate conditions for the efficient determination of multiple mycotoxins in tea samples and assessment of their drinking risks Food Chem · PMID 39353305 · DOI	Food analysis laboratory	Commercial pu-erh, green and black tea products	Pu-erh, green and black tea leaf and infusion n/a n/a · vs n/a	Aflatoxin M1 (2.15 and 3.01 micrograms per kg), fumonisin B2 (198.89) and zearalenone (87.54) were detected in the commercial pu-erh, green and black products; transfer to the infusion was 64.08 to 65.13 percent, 90.59 percent and 25.99 percent. The risk from drinking was mostly low. Mostly low risk Methods, limits and funding Outcomes: 16 mycotoxins in leaf and infusion Limitations: The abstract does not say which toxin was in which tea Funding and conflicts: No conflict of interest declared Read: abstract
Wang 2017 [Determination of mycotoxins in pu-erh tea, black tea, and green tea samples] Zhongguo Zhong Yao Za Zhi · PMID 29493150 · DOI	Food analysis laboratory	20 20 tea products (pu-erh, black and green)	Pu-erh, black and green teas leaf n/a n/a · vs n/a	Mycotoxins were detected in several samples at 0.15 to 7.31 micrograms per kg, well below state or US FDA limits. The paper is in Chinese; only the English abstract was read. Below limits Methods, limits and funding Outcomes: Aflatoxins, fumonisins, deoxynivalenol Limitations: Small; abstract only; Chinese-language paper Funding and conflicts: No relevant financial relationships Read: abstract
Wang 2022 Chemical constituents and biological properties of Pu-erh tea Food Res Int · PMID 35337597 · DOI	Narrative review human and laboratory	Review of chemistry and biological properties of pu-erh tea	Pu-erh tea and its constituents post-fermented leaf n/a n/a · vs n/a	The authors describe pu-erh as post-fermented sun-dried leaves of Camellia sinensis var. assamica, native to Yunnan, China. Claimed bioactivities include antioxidant, laxative and cholesterol- and obesity-related effects, but they state that limited human trials hardly convince the claimed therapeutic efficiency. Heavy metals, mycotoxins and other biocontaminants detected in pu-erh relate to growing, processing and storage conditions. Review; no pooled effect Methods, limits and funding Outcomes: Constituents, claimed bioactivities, contaminants Limitations: Narrative review; abstract read only Funding and conflicts: Not stated in the abstract Read: abstract
Wang 2025 A Randomized Double-Blind Trial of the Effect of Liupao Tea on Metabolic Parameters, Body Composition, and Gut Microbiota in Adults with Metabolic Syndrome Nutrients · PMID 40732996 · DOI	Controlled trial	71 71 adults with metabolic syndrome, mean age 53.5	Liupao tea (a post-fermented dark tea, not pu-erh), aged 1, 4, 7 or 10 years leaf Same daily amount in every group (not reproduced here) 90 days · vs Four aged-tea groups compared with each other; no no-tea group	LDL cholesterol fell significantly in all four groups. Total cholesterol fell in the 1-year group. Blood pressure fell in the 10-year group. Body weight and fat fell and muscle mass rose in all groups. Firmicutes/Bacteroides ratio fell in the 10-year group. No significant differences between the groups. Changes within groups; no no-tea comparison Methods, limits and funding Outcomes: Blood pressure, lipids, glucose, weight, body composition, gut microbes Limitations: Different tea from pu-erh; no no-tea control group, so changes may not be due to the tea Funding and conflicts: Not stated in the abstract Read: abstract
Xu 2022 Regulation of fungal community and the quality formation and safety control of Pu-erh tea Compr Rev Food Sci Food Saf · PMID 36201379 · DOI	Narrative review laboratory	Review of fungi in pu-erh tea	Pu-erh tea fermented leaf n/a n/a · vs n/a	Describes fungi in pile fermentation and aging, how they shape tea quality, the potential safety risks and detection methods for mycotoxins. Aims to improve safety and quality control. Review Methods, limits and funding Outcomes: Fungi, quality formation, safety Limitations: Narrative review; abstract only Funding and conflicts: No conflict statement read Read: abstract
Yang 2019 Inhibitory effects of pu-erh tea on alpha glucosidase and alpha amylase: a systemic review Nutr Diabetes · PMID 31455758 · DOI	Systematic review laboratory	6 studies on alpha-glucosidase and 7 on alpha-amylase	Pu-erh tea fermented leaf n/a n/a · vs n/a	Pu-erh tea significantly inhibited both enzymes, with high heterogeneity between studies, which the authors link to different degrees of fermentation. Enzyme inhibition with high heterogeneity Methods, limits and funding Outcomes: Inhibition of starch-digesting enzymes Limitations: Enzyme studies, not human trials; high heterogeneity Funding and conflicts: No conflict of interest declared Read: abstract
Yang 2022 Anti-Oxidative Effect of Pu-erh Tea in Animals Trails: A Systematic Review and Meta-Analysis Foods · PMID 35564056 · DOI	Meta-analysis animal	Animal studies found by a database search up to 21 February 2020	Pu-erh tea extracts fermented leaf extracts Differed Differed · vs Control animals	Pu-erh lowered serum MDA (SMD -4.19; 95% CI -5.22 to -3.15; I2 93.67%), raised SOD (SMD 2.41; 1.61 to 3.20; I2 91.36%) and raised GSH-Px (SMD 4.23; 3.10 to 5.36; I2 93.69%). The authors call the anti-oxidation effect a long-held conventional wisdom with limited supporting evidence. Large effects in animals, very high heterogeneity (MDA -5.22 to -3.15) Methods, limits and funding Outcomes: Serum MDA, SOD and GSH-Px Limitations: Animals only; very high heterogeneity; blood markers only Funding and conflicts: No conflict of interest declared Read: abstract
Zhong 2022 Hot Tea Drinking and the Risk of Esophageal Cancer: A Systematic Review and Meta-Analysis Nutr Cancer · PMID 34818954 · DOI	Meta-analysis	12 case-control studies, 5,253 cases and 8,273 controls	Hot tea drinking tea n/a n/a · vs Lower temperature	Pooled OR 2.04 (95% CI 1.78 to 2.31). The authors call the evidence limited. OR 2.04 (1.78 to 2.31) Methods, limits and funding Outcomes: Esophageal cancer Limitations: Observational case-control; pu-erh not separated Funding and conflicts: Not stated Read: abstract
n/a 2024 FDA: Spilling the Beans: How Much Caffeine Is Too Much? (content current as of 2024-08-28) n/a · Source	Authoritative guidance n/a	n/a	n/a n/a n/a n/a · vs n/a	Cites 400 mg a day as an amount not generally associated with negative effects in most adults; lists signs of too much caffeine; says sensitivity varies and some conditions and medicines raise it; advises pregnant and breastfeeding people to ask a provider. Methods, limits and funding Outcomes: Cites 400 mg a day as an amount not generally associated with negative effects in most adults; lists signs of too much caffeine; says sensitivity varies and some conditions and medicines raise it; advises pregnant and breastfeeding people to ask a provider. Limitations: Consumer guidance page, read 2026-10-25. Read: full-text
n/a 2026 NHS: Foods to avoid in pregnancy (caffeine section) n/a · Source	Authoritative guidance n/a	n/a	n/a n/a n/a n/a · vs n/a	Says not to have more than 200 mg of caffeine a day in pregnancy; about 75 mg in a cup of tea; too much caffeine linked with miscarriage and stillbirth. Methods, limits and funding Outcomes: Says not to have more than 200 mg of caffeine a day in pregnancy; about 75 mg in a cup of tea; too much caffeine linked with miscarriage and stillbirth. Limitations: Guidance page, read 2026-10-25; page date not shown. Read: full-text
n/a 2026 PubChem: Caffeine, CID 2519 (retrieved 2026-10-25) n/a · Source	Database record n/a	n/a	n/a n/a n/a n/a · vs n/a	Formula C8H10N4O2. Methods, limits and funding Outcomes: Formula C8H10N4O2. Limitations: Database record. Read: full-text
n/a 2026 PubChem: Gallic acid, CID 370 (retrieved 2026-10-25) n/a · Source	Database record n/a	n/a	n/a n/a n/a n/a · vs n/a	Formula C7H6O5. Methods, limits and funding Outcomes: Formula C7H6O5. Limitations: Database record. Read: full-text
n/a 2026 GBIF Backbone Taxonomy: Camellia sinensis var. assamica (J.W.Mast.) Kitam. (retrieved 2026-10-25) n/a · Source	Database record n/a	n/a	n/a n/a n/a n/a · vs n/a	Accepted variety of Camellia sinensis, family Theaceae, kingdom Plantae. A search also lists the Steenis authority record as accepted and the Masters authority record as its synonym. Methods, limits and funding Outcomes: Accepted variety of Camellia sinensis, family Theaceae, kingdom Plantae. A search also lists the Steenis authority record as accepted and the Masters authority record as its synonym. Limitations: Taxonomic database record, not a study. Read: full-text

What we do not know yet

What the evidence supports: very low certainty for weight, no trial for cholesterol or blood pressure, and animal-only results for antioxidant effects.
No randomised trial of pu-erh as a drink was found.
The one human pu-erh trial used an extract in 36 people and has an erratum that was not read.
Pu-erh was often not separated from other dark teas in observational data.
Mycotoxin and metal data come from small sample sets; the EMA, EFSA and IARC were not checked for pu-erh.

How new research is added

New studies are found by a saved PubMed search and 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".

Metabolic 2

▼

Body weight and BMI

Lowered in trials

Weight in kilograms and weight relative to height.

Very low certainty

Results and what it means

Why it was measured

To see whether pu-erh extract changes weight.

Statistical vs. clinical meaning

One small extract trial; size of change not given in the abstract.

Safety implication

No side effects were reported in the trial.

Study	Result	People	Product
¹⁰	Weight and BMI fell in the extract group; differences from placebo were significant from week 8	36 pre-obese Japanese adults	Pu-erh water extract in barley tea, 12 weeks

¹⁰

↕

LDL cholesterol

Mixed results in trials

The cholesterol carried in the blood that is linked with higher heart disease risk.

Not enough evidence

Results and what it means

Why it was measured

To see whether tea changes blood fats.

Statistical vs. clinical meaning

None of these is a pu-erh result.

Safety implication

None from the numbers.

Study	Result	People	Product
⁹	No significant change in LDL	798 people in 14 trials	Green or black tea, 4 to 24 weeks (no pu-erh)
²⁴	LDL fell significantly in all four groups given Liupao tea aged 1, 4, 7 or 10 years; no no-tea group	71 adults with metabolic syndrome	Liupao tea (post-fermented, not pu-erh), 90 days

^{9 24}

Other 4

▼

Visceral (belly) fat area on CT

Lowered in trials

The area of fat around the organs, measured on a CT scan slice at the navel.

Very low certainty

Results and what it means

Why it was measured

Belly fat is linked to metabolic risk.

Statistical vs. clinical meaning

A scan measure, not a health outcome; one small trial.

Safety implication

None reported.

Study	Result	People	Product
¹⁰	Visceral fat area significantly smaller (P under .05) at 12 weeks than placebo	36 pre-obese Japanese adults	Pu-erh water extract in barley tea

¹⁰

▼

Progression from prediabetes to type 2 diabetes

Lowered in trials

Whether a person with raised blood sugar goes on to be diagnosed with type 2 diabetes.

Very low certainty

Results and what it means

Why it was measured

To see whether tea drinkers differ from non-drinkers.

Statistical vs. clinical meaning

An association only; confidence interval is wide.

Safety implication

Do not change diabetes care on this basis.

Study	Result	People	Product
¹²	Dark tea drinkers: odds ratio 0.28 (95% CI 0.11 to 0.72) for progression compared with non-drinkers	2,662 Chinese adults with prediabetes, about 3 years	Self-reported dark tea drinking (pu-erh not separated)

¹²

▼

Malondialdehyde (MDA), an oxidative stress marker

Lowered in trials

A by-product of fat damage by free radicals, used as a marker of oxidative stress.

Not enough evidence

Results and what it means

Why it was measured

To test the claim that pu-erh is an antioxidant.

Statistical vs. clinical meaning

Animal result; not a health outcome.

Safety implication

None.

Study	Result	People	Product
²⁷	Serum MDA lower (SMD -4.19, 95% CI -5.22 to -3.15; I2 94 percent)	Animals in pooled studies	Pu-erh tea extracts

²⁷

▲

Antioxidant enzymes SOD and GSH-Px

Raised in trials

Enzymes the body makes to neutralise free radicals.

Not enough evidence

Results and what it means

Why it was measured

To test the claim that pu-erh supports antioxidant defences.

Statistical vs. clinical meaning

Animal result with very high heterogeneity.

Safety implication

None.

Study	Result	People	Product
²⁷	Serum SOD higher (SMD 2.41, 95% CI 1.61 to 3.20) and GSH-Px higher (SMD 4.23, 95% CI 3.10 to 5.36)	Animals in pooled studies	Pu-erh tea extracts

²⁷

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

Caffeine: pu-erh is a caffeinated tea. Pu-erh comes from the tea plant and contains caffeine. One lab study found about 13 mg per 200 mL, close to black tea, with more released by longer brewing; other teas and brands will differ. The FDA lists increased heart rate, palpitations, high blood pressure, poor sleep, anxiety, jitters, upset stomach, nausea and headache as signs of too much caffeine, and says people vary widely in sensitivity. Authoritative guidance ^{2 29}
Pregnancy: caffeine counts toward the daily limit. The NHS says not to have more than 200 mg of caffeine a day in pregnancy and estimates 75 mg in a cup of black or green tea. It links too much caffeine with a higher chance of miscarriage and stillbirth. A 2024 review of 59 papers found links with pregnancy loss and low birth weight, and said some studies saw problems below 200 mg a day. A 2024 meta-analysis linked the highest tea-drinking groups with a small rise in high blood pressure disorders of pregnancy. The FDA suggests talking to a health care provider if you are pregnant or breastfeeding. No pu-erh-specific pregnancy study was found. Authoritative guidance ^{30 17 1 29}
Mould, mycotoxins and storage. Pu-erh is made with microbes (fungi grow during pile fermentation and aging), and a 2022 review discusses fungi, mycotoxin risk and testing. Studies that measured pu-erh found low levels: 31 stored pu-erh samples had no pesticide residues detected and mycotoxins well below official limits, with aflatoxins under 1 ppb even in tea stored over 30 years. A survey of 120 post-fermented tea samples found fumonisins in 20 percent at very low intake. A 2026 meta-analysis of tea mycotoxins found black tea the most contaminated, and reported lower rates in high-income countries. Quality, storage and sourcing all matter, and these are findings from tested samples, not a guarantee for any tea you buy. Tea that is visibly mouldy is a reason not to drink it (common-sense precaution, not from a source). Food analysis ^{25 4 16 5 21 22}
Live microbes in the brew. A 2025 lab study found pu-erh had the highest live bacterial count among four teas. Two potentially harmful species, Staphylococcus epidermidis and Bacillus cereus, were found among isolates from the teas tested (the abstract does not say which tea). Live bacteria, including a spore-forming probiotic species, were still found in pu-erh brewed at 90 C. If your immune system is weak, ask your doctor. Lab only ²⁰
Iron: tea can lower iron absorption. In a trial with adults, black tea cut iron absorption from a meal by 79 to 94 percent and herb teas by 47 to 84 percent. Pu-erh was not tested, but it is a tea rich in polyphenols. If your iron is low, ask a clinician when to drink tea relative to meals. Human study ⁸
Fluoride varies by tea. Tea plants take up fluoride. In 170 Chinese tea samples pu-erh had the highest average fluoride of four tea types, and 4.7 percent of all samples were above China's limit; estimated adult intake was still below the tolerable level used there. In a Polish study pu-erh infusions were lower than black and green. Fluoride matters most for young children and very heavy tea drinkers. Food analysis ^{18 19 14}
Very hot tea and the food pipe. Two meta-analyses of observational studies linked drinking hot tea with higher risk of oesophageal squamous cell cancer (odds ratios 1.79 and 2.04). Neither looked at pu-erh alone. Let tea cool before drinking. Systematic review ^{13 28}

Side effects 4

Effect	How often	Severity and recovery	Evidence
Caffeine effects (fast heartbeat, jitters, poor sleep, upset stomach, headache) Listed by the FDA as signs of too much caffeine from any source.	Depends on amount and sensitivity; no rate for pu-erh was found	mild to moderate Reversible when caffeine is cut back	Authoritative guidance ²⁹
No side effects in the one pu-erh extract trial The trial is small and short; absence of reports is not proof of safety.	0 reported in 36 adults over 12 weeks	none reported n/a	Human study ¹⁰
Lower iron absorption from meals Dose-dependent on the polyphenol content of the drink.	Seen in a trial with black tea and herb teas; pu-erh not tested	mild; matters if iron is low Reversible	Human study ⁸
Mycotoxin or microbial contamination in poorly stored tea No human illness case from pu-erh was found in the searches run.	Low in tested pu-erh samples; no rate for illness found	unknown Unknown	Food analysis ^{25 4 20}

Liver

No human liver injury report linked to pu-erh tea was found in the PubMed searches run for this page. This is not proof that none exists. The liver warnings that exist for green tea concern concentrated green tea catechin extracts, which are a different product. The one pu-erh extract trial reported no adverse effects and no significant changes in blood tests over 12 weeks in 36 adults. ¹⁰

How often. No rate could be found.

Monitoring. No agency monitoring advice for pu-erh was found.

This is a safety connection. It is not evidence that Pu-erh Tea supports liver health.

Medicines and supplements 5

With	Why it matters	Importance	Evidence	What to do
Other caffeine sources food	Caffeine adds up across tea, coffee, cola and energy drinks.	The FDA cites 400 mg a day as an amount not generally linked with negative effects in most adults; the NHS says 200 mg in pregnancy.	Authoritative guidance Moderate certainty ^{29 30}	Count tea toward your daily total.
Medicines that make you more sensitive to caffeine prescription	The FDA says some conditions and some medications can make people more sensitive to caffeine's effects. It does not name them on the page read.	Not quantified for pu-erh.	Authoritative guidance Low certainty ²⁹	Ask your pharmacist whether any of your medicines affect caffeine.
Iron supplements and iron-poor diets supplement	Tea polyphenols bind iron in the gut.	Black tea cut iron absorption from a meal by 79 to 94 percent in one study; pu-erh was not tested.	Human study Low certainty ⁸	If your iron is low, ask a clinician about timing.
Warfarin and other blood thinners prescription	No pu-erh-specific report was found. Green tea has a case report (see the Green Tea page).	Unknown for pu-erh.	Not established Not enough evidence	Tell your prescriber about big changes in tea habits.
Diabetes medicines prescription	Pu-erh slows starch-digesting enzymes in lab studies; no human interaction data were found.	Unknown.	Lab only Not enough evidence ²⁶	Ask your pharmacist if you take blood sugar medicines and drink a lot of tea.

Who should check first 6

Situation	Advice	Evidence
Pregnancy	Pu-erh is not named as banned, but it counts toward the 200 mg a day caffeine limit set by the NHS. No pu-erh-specific pregnancy study was found. Ask your midwife or doctor.	Authoritative guidance ^{30 17}
Breastfeeding	The FDA suggests talking to a health care provider about limiting caffeine. No pu-erh-specific breastfeeding source was read.	Authoritative guidance ²⁹
Low iron or iron-deficiency anemia	Tea can lower iron absorption; ask a clinician.	Human study ⁸
Weakened immune system	Pu-erh brews can hold live bacteria. Ask your doctor before drinking aged or fermented tea.	Lab only ²⁰
Heart rhythm problems, anxiety or sleep problems	Caffeine can worsen these; ask your doctor.	Authoritative guidance ²⁹
Children	No pu-erh-specific child source was found. Caffeine and fluoride are the points to ask a paediatrician about.	Gap ¹⁴

Overdose, product quality and regulators

Summary. No toxicity study of pu-erh in people was found. Concerns in the sources are contaminants (mycotoxins, metals, fluoride) and caffeine, not the leaf itself.

Animal. No toxicity study read.

Human doses studied. A 12-week extract trial in 36 adults reported no adverse effects.

High dose or long term signals. Not described in the sources read.

Overdose response. Not described in the sources read.

Genotoxicity. Not read.

Toxic or hazardous parts. Leaf is the part used. No other part was assessed in the sources read.

Tested pu-erh samples were mostly within official limits for mycotoxins, pesticides and metals, but tea is a farm and storage product and results come from small sample sets. Quality of the particular tea you buy is not known from these papers.

Mycotoxins and aged tea. 31 pu-erh samples (raw and ripened, various storage times): no pesticide residues detected, mycotoxins well below official limits, aflatoxins under 1 ppb even after more than 30 years of storage. A 20-sample study found tea mycotoxins from 0.15 to 7.31 micrograms per kg, below regulatory limits. A 2025 method study detected aflatoxin M1, fumonisin B2 or zearalenone in commercial pu-erh, green and black teas, with mostly low risk (the abstract does not say which toxin was in which tea). Reviewers note that mould growth during processing is a concern and call for better control. ^{4 22 21 25 15 5}

Fumonisins in post-fermented tea. Found in 24 of 120 samples at 2.14 to 18.28 micrograms per kg; average intake was 0.026 percent of the tolerable daily intake. The abstract says post-fermented tea, not pu-erh by name. ¹⁶

Heavy metals. Raw pu-erh samples from different storage years had arsenic, chromium, cadmium, lead, copper, zinc, manganese and mercury below Chinese national limits and a hazard index of 0.221 for adults; storage years did not change metal levels. Mercury in 86 Polish tea samples, including pu-erh, was below the EU standard. ^{11 3}

Fluoride. Mean fluoride in 170 Chinese tea samples was highest in pu-erh among four types (164 mg/kg versus 96.8 to 121). In Poland pu-erh infusions ranked below black, green and Earl Grey tea, and infusions were not high enough to cause fluorosis. A 2008 study warned about dental fluorosis for children drinking large amounts of black tea. ^{18 19 14}

Live microbes. Pu-erh had the highest viable bacterial count among four teas, and live bacteria survived brewing at 90 C in the lab. ²⁰

Body	Action	Date
NHS (UK) (United Kingdom)	Says not to have more than 200 mg of caffeine a day in pregnancy; estimates 75 mg in a cup of tea; links too much caffeine with miscarriage and stillbirth. source	2026 (page read 2026-10-25)
FDA (United States)	Cites 400 mg of caffeine a day as an amount not generally associated with negative effects in most adults; lists signs of too much caffeine; advises pregnant, trying-to-conceive or breastfeeding people to talk to a provider. source	2024-08-28

When to get medical help

Palpitations, chest pain, fainting or a racing heartbeat after tea: stop and get medical help; call emergency services if severe.
Yellow skin or eyes, dark urine or severe tiredness while taking any concentrated tea extract: stop it and seek medical care.
Vomiting, severe stomach pain or fever after drinking tea that was stored badly or looked mouldy: get medical care.
Marked tiredness, pale skin or breathlessness in a heavy tea drinker with low iron: see a clinician.

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 pu-erh tea?

Pu-erh is a dark tea from Yunnan, China, made from post-fermented, sun-dried tea leaves. Microbes change it during fermentation and aging. It is made from the tea plant, so it contains caffeine.

^{23 25}

Is pu-erh the same as black tea?

No. In English, black tea usually means fully oxidised tea. Pu-erh is post-fermented by microbes. Caffeine was similar in one lab study, but results for one do not apply to the other.

^{2 23}

Does pu-erh tea help with weight loss?

This is not shown. The one human trial used a pu-erh extract in barley tea in 36 adults and found lower weight and belly fat over 12 weeks. No trial of the drink was found, and reviewers say limited human trials hardly convince the claims.

^{10 23 6}

Does pu-erh tea lower cholesterol?

Not shown in people. Pooled green and black tea trials found no effect, a different dark tea lowered LDL in a trial with no no-tea group, and the pigment worked in mice.

^{9 24 7}

Does pu-erh tea help with blood sugar or diabetes?

A Chinese cohort linked dark tea drinking with less progression from prediabetes to diabetes, but pu-erh was not separated and this does not show cause. Lab work shows enzyme slowing. Ask your doctor before changing diabetes care.

^{12 26}

Is pu-erh an antioxidant tea?

Animal studies changed oxidative-stress markers, but the authors call the claim long-held with limited supporting evidence. No human trial was found.

²⁷

Does pu-erh tea contain caffeine?

One lab study measured about 13 mg per 200 mL, comparable to black tea, with more released by longer brewing. Other teas and brands will differ. The NHS counts about 75 mg in a cup of tea, so it counts toward your daily total.

^{2 30}

Is pu-erh tea safe in pregnancy?

It counts toward the caffeine limit: the NHS says no more than 200 mg a day. A 2024 review found links with pregnancy loss and low birth weight, with some seen below that level. No pu-erh-specific study was found. Ask your midwife or doctor.

^{30 17 1}

Can pu-erh tea contain mould or mycotoxins?

It is made with microbes and a review discusses mycotoxin risk. In 31 stored pu-erh samples no pesticide residues were found and mycotoxins were well below limits, even after more than 30 years. Results come from small sample sets, so they are not a guarantee. Tea that looks mouldy should not be drunk.

^{25 4 22 21}

Does pu-erh tea contain fluoride or heavy metals?

In 170 Chinese samples pu-erh had the highest average fluoride of four tea types, with estimated adult intake below the tolerable level. In a Polish study it was lower than black and green tea. Raw pu-erh metals were below Chinese limits and mercury was below the EU standard.

^{18 19 11 3}

Does pu-erh tea interact with medicines or iron?

No pu-erh-specific interaction was found. The FDA says some medicines raise sensitivity to caffeine, so ask your pharmacist. Tea lowered iron absorption in a trial (black tea 79 to 94 percent; pu-erh was not tested).

^{29 8}

Is very hot tea a problem?

Two meta-analyses of observational studies link drinking hot tea with higher esophageal cancer risk (odds ratios 1.79 and 2.04). Neither looked at pu-erh alone. Let it cool.

^{13 28}

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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 the abstracts of about 30 sources, read the NHS and FDA pages, and checked the plant name in GBIF and two compounds in PubChem. Only abstracts were read for papers. Certainty ratings are the compiler's own reading. Funding was not stated in several abstracts, so industry links are not ruled out. No study is cited that we could not verify.
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. This page is information, not a recommendation to drink or take anything.

Sources 33

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

Arafa A, Sheerah HA, Alzaydan OK, et al. The Association between Antenatal Tea Drinking and Hypertensive Disorders of Pregnancy: A Systematic Review and Meta-Analysis. Epidemiologia (Basel). 2024. PMID 38804341. DOI 10.3390/epidemiologia5020014. (abstract)
Ayakdaş G, Ağagündüz D. Determination of L-Theanine and Caffeine Contents in Tea Infusions with Different Fermentation Degrees and Brewing Conditions Using the Chromatographic Method. Foods. 2025. PMID 40647065. DOI 10.3390/foods14132313. (abstract)
Brodziak-Dopierała B, Fischer A. Analysis of Mercury Content in Various Types of Tea (Camellia sinensis) and Yerba Mate (Ilex paraguariensis). Int J Environ Res Public Health. 2022. PMID 35564885. DOI 10.3390/ijerph19095491. (abstract)
Chau SL, Zhao A, Jia W, et al. Simultaneous Determination of Pesticide Residues and Mycotoxins in Storage Pu-erh Tea Using Ultra-High-Performance Liquid Chromatography Coupled with Tandem Mass Spectrometry. Molecules. 2023. PMID 37836726. DOI 10.3390/molecules28196883. (abstract)
Guennouni M, Mannani N, Zinedine A, et al. Prevalence of mycotoxin contamination in different types of tea: a systematic review and meta-analysis. Mycotoxin Res. 2026. PMID 41627675. DOI 10.1007/s12550-025-00620-2. (abstract)
Hu Y, Huang G, Soonjae K. Tea Bioactive Compounds in Obesity Prevention and Management: Processing-Dependent Composition, Molecular Mechanisms, Human Evidence, and Translational Challenges. Int J Mol Sci. 2026. PMID 42653208. DOI 10.3390/ijms27167203. (abstract)
Huang F, Zheng X, Ma X, et al. Theabrownin from Pu-erh tea attenuates hypercholesterolemia via modulation of gut microbiota and bile acid metabolism. Nat Commun. 2019. PMID 31672964. DOI 10.1038/s41467-019-12896-x. (abstract)
Hurrell RF, Reddy M, Cook JD. Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. Br J Nutr. 1999. PMID 10999016. (abstract)
Igho-Osagie E, Cara K, Wang D, et al. Short-Term Tea Consumption Is Not Associated with a Reduction in Blood Lipids or Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Nutr. 2020. PMID 33188386. DOI 10.1093/jn/nxaa295. (abstract)
Kubota K, Sumi S, Tojo H, et al. Improvements of mean body mass index and body weight in preobese and overweight Japanese adults with black Chinese tea (Pu-Erh) water extract. Nutr Res. 2011. PMID 21745623. DOI 10.1016/j.nutres.2011.05.004. (abstract)
Li F, Lu Q, Li M, et al. Comparison and Risk Assessment for Trace Heavy Metals in Raw Pu-erh Tea with Different Storage Years. Biol Trace Elem Res. 2020. PMID 31625054. DOI 10.1007/s12011-019-01886-1. (abstract)
Li T, Rayner CK, Horowitz M, et al. The Impact of Tea Consumption on Prediabetes Regression and Progression: A Prospective Cohort Study. Nutrients. 2025. PMID 40732991. DOI 10.3390/nu17142366. (abstract)
Luo H, Ge H. Hot Tea Consumption and Esophageal Cancer Risk: A Meta-Analysis of Observational Studies. Front Nutr. 2022. PMID 35479756. DOI 10.3389/fnut.2022.831567. (abstract)
Malinowska E, Inkielewicz I, Czarnowski W, et al. Assessment of fluoride concentration and daily intake by human from tea and herbal infusions. Food Chem Toxicol. 2008. PMID 18078704. DOI 10.1016/j.fct.2007.10.039. (abstract)
Pandey AK, Samota MK, Sanches Silva A. Mycotoxins along the tea supply chain: A dark side of an ancient and high valued aromatic beverage. Crit Rev Food Sci Nutr. 2023. PMID 35452322. DOI 10.1080/10408398.2022.2061908. (abstract)
Qiu T, Zhu J, Zhang H, et al. B-Type Fumonisins in Post-Fermented Tea: Occurrence and Consumer Dietary Exposure in Guangxi, China. Toxins (Basel). 2023. PMID 37755960. DOI 10.3390/toxins15090534. (abstract)
Rohweder R, de Oliveira Schmalfuss T, Dos Santos Borniger D, et al. Caffeine intake during pregnancy and adverse outcomes: An integrative review. Reprod Toxicol. 2024. PMID 38042437. DOI 10.1016/j.reprotox.2023.108518. (abstract)
Shao L, Xu S, Wang G, et al. Fluoride in tea from Shandong Province, China and exposure assessment. Food Addit Contam Part B Surveill. 2020. PMID 31905107. DOI 10.1080/19393210.2019.1710267. (abstract)
Szmagara A, Krzyszczak A, Stefaniak EA. Determination of fluoride content in teas and herbal products popular in Poland. J Environ Health Sci Eng. 2022. PMID 36406606. DOI 10.1007/s40201-022-00811-4. (abstract)
Uhlig E, Megaelectra A, Molin G, et al. Viable and Heat-Resistant Microbiota with Probiotic Potential in Fermented and Non-Fermented Tea Leaves and Brews. Microorganisms. 2025. PMID 40431137. DOI 10.3390/microorganisms13050964. (abstract)
Wan YC, Kong ZL, Wu YS, et al. Establishment of appropriate conditions for the efficient determination of multiple mycotoxins in tea samples and assessment of their drinking risks. Food Chem. 2025. PMID 39353305. DOI 10.1016/j.foodchem.2024.141438. (abstract)
Wang L, Yang H, Xie GX, et al. [Determination of mycotoxins in pu-erh tea, black tea, and green tea samples]. Zhongguo Zhong Yao Za Zhi. 2017. PMID 29493150. DOI 10.19540/j.cnki.cjcmm.2017.0215. (abstract)
Wang S, Qiu Y, Gan RY, et al. Chemical constituents and biological properties of Pu-erh tea. Food Res Int. 2022. PMID 35337597. DOI 10.1016/j.foodres.2021.110899. (abstract)
Wang Y, Hu Q, Jiang Q, et al. A Randomized Double-Blind Trial of the Effect of Liupao Tea on Metabolic Parameters, Body Composition, and Gut Microbiota in Adults with Metabolic Syndrome. Nutrients. 2025. PMID 40732996. DOI 10.3390/nu17142371. (abstract)
Xu J, Wei Y, Li F, et al. Regulation of fungal community and the quality formation and safety control of Pu-erh tea. Compr Rev Food Sci Food Saf. 2022. PMID 36201379. DOI 10.1111/1541-4337.13051. (abstract)
Yang CY, Yen YY, Hung KC, et al. Inhibitory effects of pu-erh tea on alpha glucosidase and alpha amylase: a systemic review. Nutr Diabetes. 2019. PMID 31455758. DOI 10.1038/s41387-019-0092-y. (abstract)
Yang CY, Hung KC, Yen YY, et al. Anti-Oxidative Effect of Pu-erh Tea in Animals Trails: A Systematic Review and Meta-Analysis. Foods. 2022. PMID 35564056. DOI 10.3390/foods11091333. (abstract)
Zhong Y, Yang C, Wang N, et al. Hot Tea Drinking and the Risk of Esophageal Cancer: A Systematic Review and Meta-Analysis. Nutr Cancer. 2022. PMID 34818954. DOI 10.1080/01635581.2021.2007963. (abstract)
n/a. FDA: Spilling the Beans: How Much Caffeine Is Too Much? (content current as of 2024-08-28). n/a. 2024. (full-text)
n/a. NHS: Foods to avoid in pregnancy (caffeine section). n/a. 2026. (full-text)
n/a. PubChem: Caffeine, CID 2519 (retrieved 2026-10-25). n/a. 2026. (full-text)
n/a. PubChem: Gallic acid, CID 370 (retrieved 2026-10-25). n/a. 2026. (full-text)
n/a. GBIF Backbone Taxonomy: Camellia sinensis var. assamica (J.W.Mast.) Kitam. (retrieved 2026-10-25). n/a. 2026. (full-text)

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.