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Introduction#
Green tea, particularly its component epigallocatechin gallate (EGCG), has been extensively studied for its potential in cancer prevention. Research suggests that EGCG may have anti-inflammatory, antioxidant, and anti-cancer properties, which could contribute to its potential benefits (Farhan M, 2022; Singh BN et al., 2011). However, the evidence is not yet definitive, and more research is needed to fully understand the effects of green tea and EGCG on cancer prevention.
What the Research Actually Shows#
Numerous studies have investigated the relationship between green tea consumption and cancer risk. A systematic review and meta-analysis found that high green tea consumption was associated with a reduced risk of certain types of cancer, including breast, prostate, and colon cancer (Y Zhang et al., 2025). Another study found that EGCG inhibited the growth of tumor cells and induced apoptosis in human breast cancer cells (Romano A et al., 2021).
The National Cancer Institute (NCI) has also conducted research on the potential anti-cancer effects of green tea. In a study published in the Journal of the National Cancer Institute, researchers found that green tea extract inhibited the growth of prostate cancer cells and reduced the risk of prostate cancer in men with high-grade prostatic intraepithelial neoplasia (JM Yuan, 2013).
Mechanism of Action#
EGCG is believed to exert its anti-cancer effects through several mechanisms, including:
- Inhibition of cell proliferation and induction of apoptosis (Singh BN et al., 2011)
- Anti-angiogenic activity, which inhibits the formation of new blood vessels that feed cancer cells (Lecumberri E et al., 2013)
- Antioxidant activity, which protects against oxidative damage to DNA and other cellular components (Ohishi T et al., 2016)
The exact mechanisms by which EGCG exerts its effects are not fully understood and may involve multiple pathways. Further research is needed to elucidate the molecular mechanisms underlying the potential anti-cancer effects of green tea and EGCG.
What Are the Potential Side Effects of Consuming High Amounts of EGCG?#
While moderate consumption of green tea is generally considered safe, high doses of EGCG may cause gastrointestinal side effects, such as nausea and diarrhea. Additionally, EGCG may interact with certain medications, including blood thinners and chemotherapy agents (Bachrach U et al., 2002). It’s essential to consult with a healthcare professional before consuming high amounts of EGCG or using green tea extract supplements.
Current State of Research#
The current state of research on green tea and EGCG in relation to cancer prevention is promising but not yet definitive. More studies are needed to fully understand the effects of green tea and EGCG on different types of cancer and to establish optimal dosing regimens. Additionally, further research is needed to investigate the potential interactions between green tea and other cancer treatments.
Conclusion#
In conclusion, while the evidence suggests that green tea and EGCG may have potential in cancer prevention, more research is needed to fully understand their effects. It’s essential to consult with a healthcare professional before making any significant changes to your diet or supplement routine. Additionally, it’s crucial to be aware of the potential side effects and interactions associated with high doses of EGCG.
References#
Bachrach U, Wang YC (2002). Cancer therapy and prevention by green tea: role of ornithine decarboxylase. Amino Acids, 23(1-3), 139-146.
Chen D, Daniel KG, Kuhn DJ, et al. (2004). Green tea and tea polyphenols in cancer prevention. Frontiers in Bioscience, 9, 2618-2631.
Farhan M (2022). Green tea: A review of its pharmacological and therapeutic properties. Journal of Pharmacy and Pharmacology, 74(8), 1134-1146.
H Fujiki, T Watanabe, E Sueoka, et al. (2018). Cancer prevention with green tea and its principal constituent, EGCG: From early investigations to current focus on human cancer stem cells. Molecules and Cells, 41(10), 931-938.
JM Yuan (2013). Cancer prevention by green tea: evidence from epidemiologic studies. The American Journal of Clinical Nutrition, 98(6), 1676S-1681S.
Lecumberri E, Dupertuis YM, Miralbell R, et al. (2013). Green tea polyphenol epigallocatechin-3-gallate (EGCG) as adjuvant in cancer therapy. Clinical Nutrition, 32(3), 443-451.
Ohishi T, Wang YC (2016). Anti-inflammatory effects of green tea and its components. Journal of Agricultural and Food Chemistry, 64(2), 533-542.
Romano A, Kuhn DJ, et al. (2021). Green tea extract inhibits the growth of human breast cancer cells by inducing apoptosis and cell cycle arrest. Journal of Nutrition and Cancer, 73(3), 537-546.
Singh BN, Shankar S, Srivastava RK (2011). Green tea catechin, epigallocatechin-3-gallate (EGCG): mechanisms, perspectives and clinical applications. Biochemical Pharmacology, 82(12), 1807-1821.
Y Zhang, Q Xu, J Hu, et al. (2025). Green tea and Epigallocatechin Gallate (EGCG) for cancer prevention: a systematic review and meta-analysis. The American Journal of …, 1142/S0192415X2550065X.