Green tea extract
Supplement
polyphenol
energyheart & metabolic
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Body weight and LDL: small effects at best (ODS, NCCIH)
When to take
Daily
Take with
Food · usp advises this to lower the liver-injury risk
Studied for
The pooled weight trials ran 12–13 weeks
Pros & cons
Pros
- Green tea as a drink: no adverse effects reported
- Small total and LDL cholesterol drop in trials
- Catechins with caffeine raised energy expenditure
Cons
- The extract is linked to liver injury — HSA flags it
- Cochrane: no weight effect in the 6 non-japan trials
- Nausea, constipation, raised blood pressure reported
Sources
- NIH ODS — Dietary Supplements for Weight Loss (Health Professional), green tea section (read via archive.org capture; ods.od.nih.gov returned 403 to direct fetch) · read 2026-08-27
what it says
“the findings of these studies suggest that if green tea is an effective weight-loss aid, any effect it has is small and not likely to be clinically relevant”
- NIH ODS — Weight Loss fact sheet, 2012 Cochrane Review of green tea (via archive.org capture) · read 2026-08-27
what it says
“The trials lasted from 12 to 13 weeks, and doses of green tea catechins ranged from 141 to 1,207 mg … Green tea supplementation reduced body weight by a mean of 0.95 kg more than placebo.”
- NIH ODS — Weight Loss fact sheet, Cochrane non-Japan subgroup (via archive.org capture) · read 2026-08-27
what it says
“when the authors analyzed the six studies that were conducted outside of Japan … they found no statistically significant difference in weight loss for green tea compared to placebo.”
- NIH ODS — Weight Loss fact sheet, catechins and caffeine (via archive.org capture) · read 2026-08-27
what it says
“caffeine alone or in combination with catechins significantly increases energy expenditure in a dose-dependent fashion compared with placebo … Catechins combined with caffeine also significantly increase fat oxidation”
- NIH ODS — Weight Loss fact sheet, Minnesota Green Tea Trial liver enzymes (via archive.org capture) · read 2026-08-27
what it says
“women who consumed green tea extract containing 1,315 mg total catechins (including 843 mg EGCG) and 15.8 mg caffeine daily for 12 months had significantly increased liver enzymes compared to those taking a placebo”
- NIH ODS — Weight Loss fact sheet, USP review of green tea safety (via archive.org capture) · read 2026-08-27
what it says
“The USP noted that problems are more likely when green tea extract is taken on an empty stomach and, therefore, advises taking green tea extracts with food to minimize the possible risk of liver damage.”
- NCCIH — Green Tea (What Do We Know About Safety: beverage) · read 2026-08-27
what it says
“No safety concerns have been reported for green tea consumed as a beverage by adults. However, green tea does contain caffeine.”
- NCCIH — Green Tea (What Have We Learned: cholesterol) · read 2026-08-27
what it says
“Green tea reduced total cholesterol and low-density lipoprotein (LDL) cholesterol to a small extent, but it did not affect high-density lipoprotein (HDL) cholesterol or triglycerides.”
- NCCIH — Green Tea (Safety: extract side effects) · read 2026-08-27
what it says
“Side effects of green tea extract supplements include nausea, constipation, abdominal discomfort, and increased blood pressure.”
- NCCIH — Green Tea (Safety: liver injury and gene variant) · read 2026-08-27
what it says
“liver injury has been reported in some people who used green tea products, primarily green tea extracts in tablet or capsule form. Individuals with a specific variant of a gene … appear to be especially susceptible.”
- NCCIH — Green Tea (Safety: nadolol and atorvastatin) · read 2026-08-27
what it says
“Green tea at high doses has been shown to reduce blood levels and, therefore, the effectiveness of the drug nadolol … Green tea extract can reduce blood levels of the cholesterol-lowering drug atorvastatin.”
- NCCIH — Green Tea (Safety: raloxifene interaction) · read 2026-08-27
what it says
“A study funded by the National Center for Complementary and Integrative Health showed an interaction between green tea and the drug raloxifene, which is used to treat osteoporosis.”
- NCCIH — Green Tea (Safety: pregnancy and breastfeeding) · read 2026-08-27
what it says
“During pregnancy, caffeine intake should not exceed moderate levels. Green tea is a source of caffeine … Caffeine can pass to your infant through breast milk”
- HSA — Guidelines on Prohibited and Restricted Ingredients in Health Supplements and Traditional Medicines, GL-CHPB-1-012 Rev 001 (Oct 2025) — Annex B, item 2 (Camellia sinensis extract) · read 2026-08-27
what it says
“Camellia sinensis (extract) (green tea extract) — Rare and unpredictable cases of liver injury have been reported … Information to users to highlight potential liver injury risks, and stop use and consult doctor should there by symptoms of liver injury”
- HSA — Guidelines on Prohibited and Restricted Ingredients in Health Supplements and Traditional Medicines, GL-CHPB-1-012 Rev 001 (Oct 2025) — Annex B, item 1 (caffeine) · read 2026-08-27
what it says
“Caffeine — Known to have stimulatory effects … Information to advise consumers to limit concurrent use of caffeine-containing products such as tea and coffee when taking this product.”
- iHerb Singapore — Green Tea Extract category (default order, 1 - 48 of 56 results) · read 2026-08-27
what it says
“California Gold Nutrition, Green Tea Phytosome, 150 mg … NOW Foods, EGCg, Green Tea Extract, 400 mg … Life Extension, Mega Green Tea Extract, Decaffeinated … NOW Foods, Green Tea Extract, 400 mg … MRM Nutrition, Matcha Green Tea”
Updated 2026-08-29. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.