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Metabolic Health

Green Tea

Camellia sinensis

Green tea is a widely consumed botanical beverage containing catechins, including epigallocatechin gallate (EGCG), together with naturally occurring caffeine. Human research suggests possible small effects on body weight, adiposity and selected metabolic measures, but the magnitude of benefit is modest and varies by preparation, dose, population and study design.

Evidence Emerging
Clinical confidence Low
Safety Caution
Preparation reviewed

Brewed green tea is assessed separately from concentrated green tea extracts and supplements because catechin exposure, caffeine exposure and safety can differ substantially between preparations.

Green tea leaves with a prepared cup of green tea
Botanical identity, formulation and preparation matter. Findings from one preparation should not automatically be applied to another.

Evidence assessment

What does the current evidence support?

Emerging

Current evidence summary

Recent systematic reviews and meta-analyses suggest that green tea supplementation can produce small reductions in body weight and adiposity measures in adults. A 2025 meta-analysis reported average reductions of approximately 0.74 kg in body weight, 0.29 kg/m² in BMI, 1.04 cm in waist circumference and 0.65 percentage points in body-fat percentage. A 2024 network meta-analysis also found small weight effects, while rating the certainty of evidence as low or very low for several comparisons. These findings support a possible modest adjunctive role rather than a stand-alone weight-management treatment.

Evidence limitations

The evidence base is heterogeneous. Studies use different catechin and caffeine doses, brewed tea and concentrated extracts, different intervention durations and different participant populations. Many trials assess supplements rather than ordinary brewed tea. Statistically significant changes are generally small, and findings should not be interpreted as evidence that green tea produces weight loss comparable with licensed obesity medicines or structured clinical treatment.

Clinical confidence Low

BodyRepair has low confidence in practical use because the evidence is limited, inconsistent, difficult to apply or affected by important safety or preparation concerns.

Safety assessment

Safety is assessed separately from evidence of benefit.

Caution

Current safety summary

Brewed green tea is generally considered lower risk for most adults when consumed as a beverage, although it contains caffeine. Concentrated green tea extracts require greater caution. Green tea extract supplements can cause gastrointestinal adverse effects and increased blood pressure, and uncommon cases of liver injury have been reported, particularly with tablet or capsule extracts. EFSA has identified liver-safety concern at supplemental EGCG exposure of 800 mg per day or above and was unable to establish a safe supplemental dose below that level from the available evidence.

Reported or relevant adverse effects

  • Caffeine-related effects may include sleep disturbance, nervousness, palpitations or gastrointestinal discomfort in susceptible people.
  • Green tea extract supplements may cause nausea.
  • Green tea extract supplements may cause constipation.
  • Green tea extract supplements may cause abdominal discomfort.
  • Green tea extract supplements may increase blood pressure in some people.
  • Uncommon liver injury has been reported primarily with concentrated green tea extracts in tablet or capsule form.

Interaction review

Drug, Supplement & Botanical Interactions

Potential interactions should be reviewed in relation to the botanical preparation, dose, frequency, prescribed medicines, supplements and individual health circumstances.

Caution
Prescription medicine

Nadolol

Established

High green tea intake has been shown to reduce blood levels of nadolol and may therefore reduce the effectiveness of this beta-blocker.

Recommended action

People taking nadolol should discuss regular or high green tea intake, particularly concentrated products, with their prescriber or pharmacist.

Prescription medicine

Atorvastatin

Established

Green tea extract can reduce blood levels of atorvastatin.

Recommended action

Discuss concentrated green tea extract use with a pharmacist or prescriber if taking atorvastatin.

Prescription medicine

Raloxifene

Emerging

Research funded by NCCIH has identified an interaction between green tea and raloxifene, a medicine used in osteoporosis treatment.

Recommended action

People taking raloxifene should discuss regular green tea supplement use with their pharmacist or prescriber.

General interaction review

Other prescription medicines

Under Review

Green tea and concentrated green tea extracts may interact with additional medicines. The clinical importance may depend on the medicine, product, dose and frequency of use.

Recommended action

Check concentrated green tea supplement use with a pharmacist when taking regular prescription medicines.

BodyRepair safety rule

Do not stop, replace or alter prescribed treatment because of botanical information without advice from an appropriately qualified healthcare professional.

Clinical suitability

Contraindications & Clinical Cautions

Contraindications should be considered in relation to the botanical species, preparation, dose, diagnosed conditions, age, pregnancy, breastfeeding and planned procedures.

Caution
Clinical condition

Liver disease or previous liver injury

Medical Supervision Required Established

Concentrated green tea extracts require particular caution because liver injury has been reported with extract products and higher supplemental EGCG exposure.

Recommended action

Seek professional advice before using concentrated green tea extracts. Stop use and obtain medical advice if symptoms suggestive of liver injury develop.

Life stage

Pregnancy

Caution Clinical Practice

Green tea contributes to total daily caffeine intake during pregnancy.

Recommended action

Include green tea when calculating total caffeine intake and follow current pregnancy guidance from a healthcare professional. Concentrated supplements should not be treated as equivalent to normal beverage intake.

Life stage

Breastfeeding

Caution Clinical Practice

Caffeine passes into breast milk. Low-to-moderate maternal caffeine intake is usually tolerated, while higher intake can contribute to infant fussiness or poor sleep.

Recommended action

Include green tea within total caffeine intake and seek professional advice if using concentrated extracts or consuming high amounts.

Individual sensitivity

Caffeine sensitivity

Caution Established

Green tea naturally contains caffeine unless specifically decaffeinated.

Recommended action

Reduce intake or choose a lower-caffeine preparation if caffeine causes palpitations, anxiety, sleep disturbance or other symptoms.

BodyRepair clinical rule

Where pregnancy, breastfeeding, surgery, a diagnosed condition, significant symptoms or prescribed treatment are relevant, professional review should take priority over self-directed use.

BodyRepair Interpretation

What BodyRepair concludes from the current record.

Green tea may have a small supportive role within a broader nutrition, movement and weight-management strategy, particularly where it replaces higher-calorie drinks or forms part of an established dietary pattern. The evidence does not support presenting green tea as a stand-alone obesity treatment, a rapid weight-loss intervention or an alternative equivalent to licensed weight-management medicines. BodyRepair distinguishes ordinary brewed green tea from concentrated extracts because the evidence, exposure and safety profile are not interchangeable.

Living evidence record

Evidence Timeline

New studies, safety information, corrections, editorial decisions and version changes remain visible here.

9 August 2026 Canonical Review
Human Reviewed

Green Tea upgraded to the BT-013 canonical evidence standard.

The record was expanded to include quantified weight-related evidence, clearer separation of beverage and extract safety, additional medicine interactions, breastfeeding guidance and a formal source register.

Source: BodyRepair Editorial Review BodyRepair reviewed: 9 August 2026
6 May 2025 Systematic Review
Emerging

Dose-response meta-analysis reports small reductions in adiposity measures.

A systematic review and dose-response meta-analysis of randomized controlled trials reported average reductions of approximately 0.74 kg in body weight, 0.29 kg/m² in BMI, 1.04 cm in waist circumference and 0.65 percentage points in body-fat percentage with green tea supplementation.

Source: International Journal of Food Sciences and Nutrition BodyRepair reviewed: 9 August 2026
5 November 2024 Systematic Review
Emerging

Network meta-analysis finds small weight effects with limited certainty.

A systematic review and network meta-analysis of randomized trials evaluated tea and coffee interventions for adult body weight and reported small effects, with certainty rated using GRADE and important limitations across the evidence base.

Source: British Journal of Nutrition BodyRepair reviewed: 9 August 2026
December 2024 Interaction Review
Clinical Practice

NCCIH updates green tea medicine-interaction guidance.

NCCIH records clinically relevant interactions involving nadolol and atorvastatin and notes evidence of an interaction with raloxifene.

Source: National Center for Complementary and Integrative Health BodyRepair reviewed: 9 August 2026
18 April 2018 Safety Review
Safety Alert

EFSA identifies liver-safety concern with high supplemental EGCG exposure.

EFSA concluded that catechins from traditional green tea infusions are generally safe, while supplemental EGCG doses of 800 mg per day may be associated with initial signs of liver damage. EFSA was unable to identify a safe supplemental dose from the available evidence.

Source: European Food Safety Authority BodyRepair reviewed: 9 August 2026
Living evidence record

Evidence status may change as new research, safety information and human editorial review become available. BodyRepair records material changes rather than treating botanical evidence as permanently settled.

Human review history

Editorial accountability remains visible.

Version
1.1
Reviewed by
BodyRepair Editorial Review
Last reviewed
9 August 2026
Next review
9 November 2026
AI monitoring
Active
Publication authority
Human editorial approval

Source register

Evidence sources supporting this record.

NCCIH

Green Tea: Usefulness and Safety

General evidence, extract adverse effects, liver-safety information, pregnancy and breastfeeding guidance, and medicine-interaction context.

Open source
NCCIH

Herb-Drug Interactions: What the Science Says

Nadolol, atorvastatin and wider herb-drug interaction evidence.

Open source
EFSA

EFSA assesses safety of green tea catechins

Safety distinction between green tea infusions and concentrated supplemental catechins, including the 800 mg/day EGCG concern.

Open source
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

2025 quantitative evidence for body weight, BMI, waist circumference and body-fat outcomes.

Open source
PubMed

Comparative effects of tea and coffee drinking on body weight in adults: a systematic review and network meta-analysis of randomised trials

2024 systematic review, network meta-analysis and GRADE-based certainty assessment of adult weight outcomes.

Open source

Future evidence monitoring

AI can monitor evidence. Humans retain publication authority.

BodyRepair may use artificial intelligence to identify new research, safety notices, corrections and retractions relevant to this botanical.

AI-generated findings remain drafts until reviewed and approved through the BodyRepair editorial process.

BodyRepair Botanical Therapies

Continue exploring the botanical evidence library.

Return to Botanical Therapies or explore the wider Evidence Centre.

Botanical Therapies Evidence Centre