Herb Profile

Green Tea

Camellia sinensis

Green Tea (Camellia sinensis) carries a Grade A rating — strong evidence.

Last reviewed: 3 sources citedReport a correctionProfile-wide ·A Strong

Use extra caution Liver risk at high dose extracts Details

Evidence
Strong Evidence
Typical onset
Varies by prep
Safety rating
Moderate caution
Best for
Antioxidant, Metabolic, Cardiovascular, Stress resilience
Avoid / review if
Stimulants, Hepatotoxic Drugs
Green Tea monograph visual
Generated profile category visual

At a glance

From this profile's structured data
Evidence
Grade A
Safety
Liver risk at high-dose extracts
Profile context
antioxidant, metabolic, cardiovascular
Next steps

Continue reading

Safety

Safety & Cautions

Liver risk at high dose extracts

Elevated caution

Caution level: Elevated. One caution category applies — read it before use.

  • Liver-SensitiveLiver-related caution language appears in the profile.
Detailed safety fields

Pregnancy, breastfeeding, and contraindications

  • Stimulants
  • Hepatotoxic Drugs

Safety classifications

  • Liver-Sensitive: Liver-related caution language appears in the profile.

Full safety note

  • Liver risk at high dose extracts

Safety labels

  • Liver-Sensitive

Evidence

Evidence Summary

Evidence lens

Most useful for practical interpretation when safety context also fits.

StrongStrong Evidence

Human clinical evidence: Present in source signals

Mechanistic / preclinical: Mechanism mappedOxidative Stress Modulation · Metabolic Regulation · Vascular Function Support

Research maturity: Established researchLong Term Human Evidence May Be Limited.

Safety boundary: Safety note availableLiver risk at high dose extracts

This profile cites 3 human studies.

Study design details
Evidence Grade

Grade A: Strong Evidence

Evaluation of methodological rigor, population reach, and evidence alignment.

Design Match
Meta-analysis
Risk of Bias
Low
Consistency
Consistent
Strongest recorded design is a meta-analysis, drawn from 8 recorded studies, 6 in people. No disagreement is recorded across them.
How evidence grades work

Each grade reflects the strength and consistency of published human evidence — not marketing claims. Grades are based on study count, design quality, effect size, consistency, and recency.

Strong
Multiple RCTs, consistent direction, adequate effect size
Moderate
Some RCTs or consistent observational data in humans
Preliminary / Mixed
Animal or in-vitro only, or conflicting human data
Traditional / Theoretical
Traditional use only; no controlled human trials
Clinical Study Summaries (8)6 human evidence sources · 0 human trials · Participant totals not consistently reported · Consistency not yet classifiable

Filter by study class

Showing 8 of 8 studies.

What the evidence actually shows

This table contains 8 structured sources, including 6 human evidence sources; 0 are human trials. A reliable participant total cannot be calculated because sample size is not consistently structured in the cited sources. Source-to-conclusion relationships are not classified in this structured set, so consistency is not yet classifiable.

Profile-wide evidence grade: see the profile grade above · Confidence: not separately assigned

What would change our conclusion?

Larger, well-controlled human trials using comparable populations, doses, preparations, and clinically meaningful outcomes could materially strengthen or weaken this conclusion. Replication in a different population or a high-quality synthesis resolving current disagreement could also materially change confidence.

StudyDesignNDoseDurationPopulationOutcomeResult & magnitudeSource

Effects of green tea supplementation on antioxidant status and inflammatory markers in adults: a grade-assessed systematic review and dose-response meta-analysis of randomised controlled trials

Background
Meta-analysis

Statistically combines results from multiple eligible studies; confidence still depends on the quality, consistency, and directness of those studies.

Some oxidative-stress and antioxidant markers improved, while CRP, IL-6, and TNF-alpha did not clearly improve.PubMed

The Association Between Green Tea Intake and Metabolic Syndrome: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Background
Meta-analysis

Statistically combines results from multiple eligible studies; confidence still depends on the quality, consistency, and directness of those studies.

Overall pooled effects were not significant for fasting glucose, HbA1c, blood pressure, or major lipid markers, although selected subgroups showed benefit.PubMed

Effect of Green Tea Extract Supplementation on Substrate Utilization: A GRADE-Assessed Systematic Review and Dose-Response Meta Analysis of Randomized Controlled Trials

Background
Meta-analysis

Statistically combines results from multiple eligible studies; confidence still depends on the quality, consistency, and directness of those studies.

Green tea extract increased fat oxidation during and after exercise in pooled analyses, with some dose-response signal.PubMed

Effects of green tea supplementation on obesity indices and adipokines in adults: a grade-assessed systematic review and dose-response meta-analysis of randomised controlled trials

Background
Meta-analysis

Statistically combines results from multiple eligible studies; confidence still depends on the quality, consistency, and directness of those studies.

Green tea supplementation produced modest pooled reductions in weight, BMI, waist circumference, and body-fat percentage; adiponectin was not clearly improved.PubMed

Effect of green tea supplementation on blood pressure in adults: a GRADE-assessed systematic review and dose-response meta-analysis of randomised controlled trials

Background
Meta-analysis

Statistically combines results from multiple eligible studies; confidence still depends on the quality, consistency, and directness of those studies.

Pooled systolic and diastolic blood pressure reductions were about 1 mmHg, with larger subgroup effects in some higher-risk populations.PubMed

Warfarin and food, herbal or dietary supplement interactions: A systematic review

Tan CSS et al. · Br J Clin Pharmacol · 2021

Background
Systematic review

Uses a predefined method to find and evaluate relevant studies, but may or may not pool their results statistically.

PubMed
Show 2 more studies

Green Tea (Camellia sinensis): A Review of Its Phytochemistry, Pharmacology, and Toxicology

Zhao T et al. · Molecules · 2022

Background
Narrative review

Summarizes selected literature without the full prespecified search and selection methods of a systematic review.

PubMed

Common Herbal Dietary Supplement-Drug Interactions

Asher GN et al. · Am Fam Physician · 2017

Background
Narrative review

Summarizes selected literature without the full prespecified search and selection methods of a systematic review.

PubMed

Dosing & Timing

Dose guidance
300 800 mg EGCG/day
How Green Tea works

Simplified mechanism pathway based on preclinical and pharmacological evidence. Does not confirm clinical efficacy.

Mechanism Pathway — How Green Tea Works

How Green Tea WorksGreen Tea acts on biological target pathways via antioxidant, leading to antioxidant efct.Green TeaBiological TargetBiological pathwayAntioxidantAntioxidant EfctCell protectionMetabolicRegulation
CompoundTarget / ReceptorMechanismEffect / Outcome
Mechanisms & biological pathways

Preclinical pathways. Proposed mechanisms from in vitro and animal research; these do not confirm clinical outcomes in humans.

  • Oxidative Stress Modulation
  • Metabolic Regulation
  • Vascular Function Support
  • Endothelial Function Support

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Guides that use Green Tea

Compare & Sourcing

Compare side-by-side tradeoffs or verify active marker guidelines.

Review available sources for Green Tea

Independent database mapping — evaluated separately from safety and efficacy scores.

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Safety first · Harm reduction

This information is educational and not medical advice. Start low, avoid risky combinations, and consult a licensed clinician before making health decisions—especially if you use medications, have diagnosed conditions, or are pregnant/breastfeeding.

Learn how we evaluate confidence, safety, and intensity on the methodology page.

Editorial Review

Checked against primary sources, cited evidence, and contraindication language before publication. Evidence claims, safety language, and affiliate modules are reviewed independently. Not personal medical advice.

Editorial Standards →

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Botanical profile context

How to interpret Green Tea

Green Tea herb profile with evidence context, key research topics, source notes, safety context, and references presented in an evidence-first format. Use this herb profile as a starting point for evidence review, not as a recommendation to start a new supplement. Botanical products can vary by plant part, extract ratio, standardization, dose, and contaminant testing, so two labels with the same common name may not behave the same way.

When reviewing Green Tea, compare the traditional-use context against the human evidence, mechanism notes, and safety cautions. Pay special attention to pregnancy, breastfeeding, liver or kidney disease, blood-pressure effects, sedation, stimulation, anticoagulant use, antidepressants, and any prescription medication overlap.

For product decisions, prefer transparent labels, named extracts, clear serving sizes, and third-party quality testing. Avoid treating a long list of possible mechanisms as proof that an herb will solve a specific condition.