Epigallocatechin Gallate
Epigallocatechin-3-Gallate
Epigallocatechin gallate (EGCG) is the main catechin in green tea with antioxidant and potential chemopreventive properties (prevents the development of malignant diseases).
What is EGCG? EGCG is the main catechin found in green tea (Camellia sinensis). Green tea polyphenols (flavonoids), including EGCG, have antioxidant activity, reduce oxidative DNA damage, and inhibit the formation of carcinogens (e.g., nitrosamines).
Metabolic and glycemic effects: A 2025 systematic review/meta-analysis of 41 randomized controlled trials found that EGCG supplementation resulted in modest reductions in fasting blood glucose and HbA1c. The effect on fasting insulin was not significant, and the overall improvement in glycemic control was assessed as unlikely to be clinically meaningful as a stand-alone intervention for most populations.
Oncology and radioprotective data: Green tea / EGCG is being investigated for cancer prevention, with possible benefit in preventing some types of cancer (bladder, esophageal, pancreatic). A large randomized controlled trial of green tea extract standardized to 150 mg EGCG twice daily for 3 years in 879 patients with prior colorectal adenomas showed a nonsignificant reduction in adenoma recurrence. In a mouse model and a cohort of patients undergoing radiotherapy, oral EGCG prophylaxis reduced radiation-induced intestinal damage associated with modulation of the gut microbiota. In a double-blind study of postoperative breast radiotherapy, topical application of an EGCG solution to the radiation field reduced radiation dermatitis and lowered the symptom index. Treatment-related adverse events were limited to stinging and itching. Green tea preparations are promoted for cancer prevention, cognitive enhancement, heart disease prevention, Parkinson’s disease prevention, hypercholesterolemia, weight loss, and other conditions; overall rated as “possibly effective” for the listed uses.
Adverse Effects and Safety Considerations: Most safety data comes from green tea products (containing EGCG plus caffeine and other ingredients); reported adverse effects include agitation, anxiety, arrhythmias, insomnia, palpitations, tachycardia, gastrointestinal upset, hepatotoxicity, hypertension, hyperglycemia, elevated cholesterol, tremor, and dependence/withdrawal, among others. Caution is advised in patients with anxiety disorders, heart disease/arrhythmias, depression, diabetes mellitus, hypertension, renal disease, and peptic ulcer disease. Use of green tea products is not recommended during pregnancy and lactation due to lack of data.
References
- Effect of Epigallocatechin Gallate on Glycemic Index: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
- Green Tea Extract to Prevent Colorectal Adenomas, Results of a Randomized, Placebo-Controlled Clinical Trial
- EGCG protects intestines of mice and pelvic cancer patients against radiation injury via the gut microbiota/D-tagatose/AMPK axis
- Efficacy of Epigallocatechin-3-Gallate in Preventing Dermatitis in Patients With Breast Cancer Receiving Postoperative Radiotherapy: A Double-Blind, Placebo-Controlled, Phase 2 Randomized Clinical Trial
- Green Tea (Camellia Sinensis, Camellia Thea, Chinese Tea Green Tea In Combination) – Adverse Effects
- Green Tea (Camellia Sinensis, Camellia Thea, Chinese Tea Green Tea In Combination) – Pharmacology
- Green Tea (Camellia Sinensis, Camellia Thea, Chinese Tea Green Tea In Combination) – Suggested Uses
- Green Tea (Camellia Sinensis, Camellia Thea, Chinese Tea Green Tea In Combination) – Warnings
- Green Tea (Camellia Sinensis, Camellia Thea, Chinese Tea Green Tea In Combination) – Pregnancy & Lactation
- Green Tea (Camellia Sinensis, Camellia Thea, Chinese Tea Green Tea In Combination) – Suggested Dosing