# Green tea and EGCG extracts

Source: https://onco.cc/technologies/green-tea-egcg/  
OnCo record `green-tea-egcg` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Drinking green tea is safe and pleasant, but a Cochrane review found no consistent evidence that it prevents cancer, and concentrated green tea extract capsules have caused liver injury and can interfere with some drugs.

## Summary

Epigallocatechin gallate (EGCG) and other catechins have antioxidant and signalling effects in cells. A 2020 Cochrane review of 142 studies, mostly observational plus a few randomised trials, found inconsistent and inconclusive evidence for cancer prevention by green tea, with low- to very-low-certainty results in both directions by cancer site. Randomised trials of EGCG extracts in prostate cancer precursors and chronic lymphocytic leukaemia showed biological activity without proven clinical benefit. Concentrated extracts (typically above 800 mg EGCG per day) are associated with hepatotoxicity, and EGCG can reduce the absorption or activity of bortezomib, some statins and beta-blockers. Tea as a beverage carries none of these concerns.

## Fields

- Kind: Technology
- Status: phase-2
- Last checked: 2026-09-10
- Tags: complementary; supportive-care; evidence:insufficient
- Principle: Catechins scavenge reactive oxygen species and modulate kinases and proteasome activity in vitro; effective concentrations are not reached by drinking tea.
- Strengths: Safe as a beverage; Extensive biological literature
- Limitations: No consistent prevention effect in Cochrane review; Extract hepatotoxicity; Bortezomib interaction

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Epigallocatechin_gallate
- Cochrane: green tea (Camellia sinensis) for the prevention of cancer (2020): https://doi.org/10.1002/14651858.CD005004.pub3
- MSK About Herbs: Green tea: https://www.mskcc.org/cancer-care/integrative-medicine/herbs/green-tea

## Connected records

- fronts: [Diet, Exercise & Lifestyle](https://onco.cc/fronts/nutrition-lifestyle/), [Prevention & Risk](https://onco.cc/fronts/prevention/), [Supportive Care & Survivorship](https://onco.cc/fronts/supportive-care/)
- technologies: [Coffee and tea intake](https://onco.cc/technologies/coffee-intake-cancer/), [Dietary supplements during cancer treatment: interactions and harms](https://onco.cc/technologies/dietary-supplements-treatment-interactions/), [Evidence-based integrative oncology](https://onco.cc/technologies/integrative-oncology/)
- drugs: [Bortezomib](https://onco.cc/drugs/bortezomib/)
- bottlenecks: [Misinformation and unproven therapies](https://onco.cc/bottlenecks/b-misinformation/)
- key papers: [Green tea (Camellia sinensis) for the prevention of cancer](https://onco.cc/key-papers/paper-filippini-cochrane-database-syst-rev/)

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