Green Tea and Health Outcomes

Green tea has long been linked with positive health outcomes. It contains antioxidants that may help to prevent DNA damage caused by free radicals, and this is why some people think that tea can help to prevent or cure cancer. However, in a recent study, researchers reported that green tea extract (GTE) does not protect against colorectal adenoma recurrence. The study findings were published in the American Journal of Gastroenterology on February 25, 2022.

Prevention of colorectal adenomas (CA) is likely to prevent colorectal cancer (CRC). Preclinical and small clinical trials suggest that epigallocatechingallate (EGCG), a major polyphenol in green tea, has a good safety profile and antineoplastic effects in the large bowel. However, larger studies exploring the effect of GTE in CA are rare. Therefore, Dr. Thomas Seufferlein and his team conducted a study to examine the effect of EGCG on the recurrence of CA.

MIRACLE Trial

The MIRACLE trial (Minimizing the Risk of Metachronous Adenomas of the Colorectum With Green Tea Extract) is a randomized, double-blind trial, in which the researchers included 879 patients who had undergone removal of one or more histologically confirmed colorectal adenomas. They were randomized to either GTE group standardized to 150mg EGCG bid (n=437) or placebo (n=477). The primary endpoint assessed was the presence of adenoma/colorectal cancer at the follow-up colonoscopy three years after randomization.

Key Findings of the Study

• The researchers noted that the safety profile of GTE was favorable with no major differences in adverse events between the two well-balanced groups.
• After 3 years, they found adenomas in 55.7% of participants in the placebo group and in 51.1% of those in the GTE group in the modified intention-to-treat population.
• They noted that this 4.6% difference was not statistically significant (adj. RR: 0.905).
• Upon per-protocol analysis, although they observed a slightly lower adenoma rate in the GTE group, they noted that it was not significant (adj. RR 0.883).

The authors concluded, "GTE was well tolerated but there was no statistically significant difference in the adenoma rate between the GTE and the placebo group in the whole study population."

For further information: DOI: 10.14309/ajg.0000000000001706

Keywords

Green tea extract, epigallocatechingallate, colorectal adenomas, colorectal cancer, MIRACLE trial, The American Journal of Gastroenterology, GTE, EGCG, antineoplastic effects, Neoplasm, Green tea.