Green tea (Camellia sinensis) has been widely studied for its potential role in cancer prevention and therapy, primarily due to its high content of polyphenols, especially epigallocatechin gallate (EGCG). Laboratory and animal studies have shown that these compounds can inhibit tumor cell proliferation, induce apoptosis (programmed cell death), and prevent the spread (metastasis) of cancer cells. They also exhibit antioxidant properties, which may help protect cells from DNA damage that can lead to cancer.

Epidemiological studies in human populations, however, have produced mixed results. Some research suggests that regular consumption of green tea may be associated with a lower risk of certain types of cancers, such as breast, prostate, and colorectal cancer. However, other studies have found no significant protective effect. Most clinical trials to date have been small, and results have been inconsistent or show only modest benefits. The evidence is stronger for cancer prevention rather than treatment, and green tea is not considered a substitute for conventional cancer therapies.

In summary, while there is promising laboratory and some epidemiological evidence to support the use of green tea in cancer prevention, robust clinical evidence in humans is limited. Thus, green tea may have a supportive role, but should not be relied upon as a primary therapy for cancer. Consult a healthcare professional before using green tea supplements, as high doses may interact with certain medications or have side effects.