Supplement evidence

041 / 575Botanical

Green tea extract

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The short answer

Concentrated catechins have small, inconsistent effects on weight or selected metabolic markers.

Evidence and scope: Mixed evidence
This status does not grade the ingredient for every goal, outcome, or person.
Important limitation: Tea-drinking associations cannot be transferred to concentrated pills or lifespan claims.
Before deciding: Concentrated extracts can cause liver injury, particularly when taken fasting.

01 / PRACTICAL GUIDE

Dose, absorption, and combinations

These are indication-specific reference or studied ranges—not a personalized prescription. Start with the objective, then check the form, label, medicines, and health conditions.

Reference range by objective

Meeting usual needsProduct-specific; avoid high-dose EGCG and follow extract standardization

Reference or studied range—not a personalized prescription. The product label or a clinician may specify a different dose.

Dose source ↗

More is not automatically better. A clinician or product label may specify a different amount.

Absorption / solubilityFormulation-dependent

Not usefully classified as a fat- or water-soluble vitamin; absorption depends on the salt, extract, delivery system, and meal.

How it is commonly taken

Always take extract with food; brewed tea has a different safety profile.

Do not combine casually

Fasting high-dose extracts increase liver-injury risk; check stimulants, warfarin, liver disease, and pregnancy.

Dose and use source ↗

Dose and use links lead to primary or official source material. Search links are discovery tools, not proof that every returned paper applies.

02 / EVIDENCE

What the research says

We keep supportive, mixed, negative, safety, and contextual findings together. The headline never replaces the underlying papers.

4research papers in this ledger

37unique primary studies represented

1,021unique participants represented

These are audited counts for this JIVANA collection, not search-result totals. Participants are counted once when multiple papers use the same cohort; review papers are not added again to participant totals.

Open the research timelineResearch timeline

Entries are ordered by publication year. A study period appears only when the source reports it.

2025

Mixed or qualifiedPMID 40497293

Effect of green tea supplementation on blood pressure in adults

Both pressures fell by about 1 mmHg on average, with high heterogeneity. This small surrogate change does not establish fewer cardiovascular events or justify replacing hypertension treatment.

Published: 202536 primary studies represented

Study design and methods

Design: GRADE-assessed dose-response meta-analysis of 36 randomized trials
Population: Adults with varied baseline blood pressure
Intervention: Green-tea supplements versus control or placebo
Outcome: Systolic and diastolic blood pressure

Open research record ↗

2017

Safety signalPMID 28765194 · NCT00917735

Effect of Green Tea Supplements on Liver Enzyme Elevation

Liver enzymes rose and 5.1% of extract users developed moderate or worse abnormalities; dechallenge and rechallenge patterns strongly implicated the extract. This is a concentrated high-dose product signal, not brewed-tea evidence.

Published: 2017Duration: 12 monthsn=1,021 participants

Study design and methods

Design: Prespecified safety analysis of a randomized, double-blind, placebo-controlled phase 2 trial
Population: 1,021 postmenopausal women with normal baseline liver enzymes
Intervention: High-dose green-tea extract or placebo
Outcome: Liver enzymes and moderate or more severe liver-test abnormalities

Open research record ↗

2016

Safety signalPMID 27188915

Liver-related safety assessment of green tea extracts in humans

Reported liver events were rare and mostly mild, but numerically more frequent with extract; the confidence interval was wide and not conclusive. Rare-event trial reporting cannot rule out clinically important idiosyncratic injury.

Published: 201634 primary studies represented

Study design and methods

Design: Systematic review and sparse-event meta-analysis of 34 randomized trials
Population: Adults in randomized green-tea-extract trials
Intervention: Green-tea extracts versus placebo
Outcome: Liver-related adverse events and enzyme elevations

Funding or conflict note: The trials may overlap the broad efficacy syntheses and are excluded from aggregate totals.

Open research record ↗

2012

Does not support the tested claimPMID 23235664 · CD008650

Green tea for weight loss and weight maintenance in overweight or obese adults

Outside-Japan trials found essentially no weight effect; heterogeneous Japanese trials ranged from small to larger losses. The review judged any average loss small, non-significant, and unlikely clinically important, with no maintenance benefit.

Published: 2012Duration: At least 12 weeksn=1,562 participants14 primary studies represented

Study design and methods

Design: Cochrane systematic review of 14 weight-loss trials plus two maintenance trials
Population: At least 1,562 overweight or obese adults in the weight-loss analyses
Intervention: Green-tea preparations versus control
Outcome: Weight, BMI, waist measures, maintenance, and adverse events

Funding or conflict note: Some interventions may overlap later blood-pressure evidence, so this review remains visible but is excluded from aggregate totals.

Open research record ↗

Unscreened discovery appendix—not evidence465 candidate publicationsSearch run: Aug 21, 2026

Complete for the displayed PubMed query at the search timestamp—not for all databases or every possible synonym. Candidates can be irrelevant, duplicate the same study, or report negative findings. They are never summed as evidence or participants until screened.

03 / SOURCES

Start with the source material

Official evidence overviewNational Center for Complementary and Integrative Health Live PubMed discovery searchNational Library of Medicine

The live search is for discovery only. Search-result counts change and are not included in the audited totals above.

Recent PubMed discovery recordsDirect links to the first 12 records returned by the reproducible search. These are discovery candidates—not reviewed summaries or a count of supportive findings.

04 / EXPERT CONTEXT

Expert context—not evidence

Expert positions are dated context—not scientific evidence. They never raise the evidence status or become consensus by repetition.

No direct, source-verified endorsement is currently recorded. Research authorship or discussion alone is not treated as endorsement.