Theaflavins (black tea extract)
Summary
Theaflavins are the red-orange polyphenols of black tea. A 240-person trial of a theaflavin-enriched green tea extract lowered LDL by 16%, but a 102-person trial of purified black tea theaflavins found no cholesterol effect. A 30-person pilot reported body-fat changes, and a single 300 mg dose modestly improved small-vessel function. Evidence remains limited and inconsistent.
Key facts
- Polyphenols formed from catechins during the enzymatic oxidation of tea leaves; unique to black tea[4][3]
- 375 mg/day of a theaflavin-enriched green tea extract for 12 weeks: LDL −16.4%, total cholesterol −11.3% in 240 adults[1]
- Purified theaflavins (about 75 mg/day) did not lower cholesterol more than placebo over 11 weeks in 102 adults[2]
- 50–100 mg/day for 10 weeks improved body-fat and muscle percentages in a 30-person pilot[3]
- A single 300 mg dose modestly improved a microcirculation index in 24 adults; 500 mg showed only a non-significant trend and lower doses had no effect[4]
- 4 graded human outcomes on this page
- October 13, 2026
How it works
ProposedAnimal and lab studies suggest theaflavins inhibit pancreatic lipase, reduce cholesterol absorption by disrupting micelle formation, and activate AMPK. Human trials have not confirmed these mechanisms directly.[5]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Cholesterol | Grade C | Improved | RCT · n = 240 · 2003 | 2 rows |
| Body fat | Grade D | Improved | Pilot RCT · n = 30 · 2017 | 1 row |
| Blood vessels | Grade D | Mixed | Crossover RCT · n = 24 · 2014 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| LDL and total cholesterol in mild to moderate hypercholesterolaemia | Improved | Grade C | RCT · n = 240 · 2003 Adults with mild to moderate high cholesterol on a low-fat diet (China) Form: Theaflavin-enriched green tea extract capsule · Dose: 375 mg/day · Duration: 12 weeks Total cholesterol fell 11.3% and LDL 16.4% from baseline, with no change in the placebo group; HDL and triglycerides did not change; no significant adverse events. | 12824094 (opens PubMed)Source [1] |
| Body fat, subcutaneous fat and skeletal muscle percentage | Improved | Grade D | Pilot RCT · n = 30 · 2017 Healthy Japanese adults Form: Theaflavins · Dose: 50 or 100 mg/day · Duration: 10 weeks Body-fat and subcutaneous-fat percentages fell and skeletal-muscle percentage rose versus placebo; a 400 mg catechin arm showed no change. | 27756182 (opens PubMed)Source [3] |
| Microvascular reactivity (EndoPAT reactive hyperaemia index) | Mixed | Grade D | Crossover RCT · n = 24 · 2014 Healthy adults Form: Theaflavins (100–500 mg) or catechins (500 mg) · Dose: Single doses of 100–500 mg · Duration: Single dose 300 mg theaflavins raised the reactive hyperaemia index (0.28, p=0.02) and 500 mg showed a trend (0.19, p=0.06); lower doses had no effect. | 25514559 (opens PubMed)Source [4] |
| Total and LDL cholesterol with purified theaflavins | No effect | No effect | RCT · n = 102 · 2010 Adults with mildly to moderately raised cholesterol Form: Purified black tea theaflavins, alone or with catechins · Dose: 77.5 mg/day theaflavins (or 75 mg plus 150 mg catechins) · Duration: 11 weeks Total and LDL cholesterol did not differ among theaflavins, theaflavins/catechins and placebo (p=0.12 and p=0.11). | 19639377 (opens PubMed)Source [2] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Black tea theaflavin extract | Varies[2][3][4] | No human absorption data in the cited trials.[2][3] | No significant adverse events in the 12-week lipid trial.[1] | Lipid, body-composition and vascular trials (50–500 mg) |
| Theaflavin-enriched green tea extract | Varies[1] | No human absorption data.[1] | Well tolerated over 12 weeks.[1] | 12-week LDL trial (375 mg/day) |
Studied doses
Doses studied in human trials ranged from 50–100 mg/day of theaflavins for 10 weeks and about 75 mg/day for 11 weeks to 375 mg/day of a theaflavin-enriched green tea extract for 12 weeks, plus single doses of 100–500 mg.[1][2][3][4]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
None found in our sources.
Who should be careful
- Medicines
- No drug-interaction studies of theaflavin extracts have been published, including with statins, anticoagulants or diabetes drugs.[1][2]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
How to read the label
- What is in the capsuleThe positive cholesterol trial used a theaflavin-enriched green tea extract; a purified theaflavin product showed no effect.[1][2]
- Dose varies tenfoldTrials ranged from about 50–100 mg/day to 375 mg/day of extract; labels should state theaflavin content, not only black tea extract weight.[1][2][3]
Cost per studied dose, without the sales pitch
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Cost per studied dose
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Frequently asked questions
What are theaflavins?
Red-orange polyphenols that form from catechins when tea leaves are oxidised to make black tea.[4]
Do theaflavins lower cholesterol?
The evidence conflicts: a theaflavin-enriched green tea extract lowered LDL 16% in 240 adults, but purified theaflavins had no effect in 102 adults.[1][2]
Do theaflavins help with weight loss?
Only a 30-person, 10-week pilot reported lower body-fat percentage; larger trials are needed.[3]
Is drinking black tea the same?
Not necessarily. Trials used concentrated extracts with defined theaflavin doses; the amount in a cup of tea was not studied here.[2][3]
Are theaflavin supplements safe?
No significant adverse events were reported in trials of up to 12 weeks; long-term safety and drug interactions are not studied.[1]
Sources
- [1]Cholesterol-lowering effect of a theaflavin-enriched green tea extract: a randomized controlled trial.. Arch Intern Med, 2003. RCT
- [2]Purified black tea theaflavins and theaflavins/catechin supplements did not affect serum lipids in healthy individuals with mildly to moderately elevated cholesterol concentrations.. Eur J Nutr, 2010. RCT
- [3]Effect of oral theaflavin administration on body weight, fat, and muscle in healthy subjects: a randomized pilot study.. Biosci Biotechnol Biochem, 2017. pilot-RCT
- [4]Effect of tea theaflavins and catechins on microvascular function.. Nutrients, 2014. crossover-RCT
- [5]The Antiobesity Effects and Potential Mechanisms of Theaflavins.. J Med Food, 2024. review
- [6]Green Tea. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. National Institute of Diabetes and Digestive and Kidney Diseases, 2020. database
What changed
- Independent adversarial review: corrected an overclaim. The 500 mg theaflavin dose did not significantly improve microvascular function (p=0.06); only 300 mg did (summary and key fact fixed). Added the green tea extract liver-injury caution (LiverTox) and industry-authorship notes. All PMIDs re-verified.
- Adversarial second pass: every PMID re-checked against NCBI esummary (title, year, no retraction, erratum or expression-of-concern flags) and every number in each evidence row re-read against its PubMed abstract (PMC full text where the abstract lacked dose or duration). Countries and funding notes kept only where the abstract or full text states them; interactions listed only where a source supports them, otherwise stated as unstudied.
- First draft. Every PMID checked against NCBI E-utilities esummary (title and year taken from the record) and abstracts read for the cited rows.