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Herbal / botanical

Green tea and EGCG

catechin extract

Green tea contains catechins (EGCG) and caffeine, studied for weight, cholesterol and heart health.

Evidence: Limited to modest

NCCIH notes catechins and caffeine may have a modest effect on body weight; green tea extract modestly lowered total and LDL cholesterol but not HDL or triglycerides; heart benefits are seen in Asian but not Western populations; cancer results are inconsistent.

At a glance

Typical studied dose
NCCIH does not give standard doses. Brewed green tea is a typical food-level use; concentrated extracts are higher in catechins.

Food sources

Plant sources
Green tea leaves (brewed tea), matcha.

Background and testing

This is not an essential nutrient, so there is no deficiency to diagnose.

Who tends to use it
People who drink little tea and want catechin intake from food.
How it is tested
No test for need. Liver enzymes may be checked if symptoms develop.

Supplement forms

Common forms
Brewed tea, matcha, green tea extract capsules, powders, decaffeinated extracts.
More effective
Brewed or matcha tea as a food; for extracts, lower catechin doses with food and a clinician's advice.
Less effective
Concentrated EGCG capsules on an empty stomach; fat-burner blends with high caffeine; long-term high-dose use.

Safety, interactions and halal notes

Safety and interactions
Liver injury is uncommon but has been reported, particularly with concentrated extracts in tablets or capsules; about 5-15% of Americans carry a genetic variant that raises susceptibility. Extracts may cause nausea, constipation, abdominal discomfort and higher blood pressure. Green tea can reduce the effects of nadolol, atorvastatin and raloxifene.
Who should avoid it or ask a clinician first
Pregnant and breastfeeding people (caffeine), people with liver disease or the HLA-B*35:01 variant, and those on the medicines above.
Halal note
Plant-based. Check capsule shells and flavorings.

Frequently asked questions

Is green tea extract safe?

Brewed tea is generally safe in moderation. Concentrated extracts have caused liver injury in rare cases.

Sources

  1. Green Tea (NCCIH)

← Back to the full nutrient guide

This page is for education only and is not medical advice. These statements have not been evaluated by the Food and Drug Administration. Supplements are not intended to diagnose, treat, cure or prevent any disease. Talk to a qualified clinician before starting a supplement, especially if you are pregnant, breastfeeding, take medicine or have a medical condition. Daily needs are US reference intakes for adults 19-50.

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