Researchers have investigated green tea as a potential protectant against cancer. This review focuses on studies of green tea in humans.
Green tea contains polyphenols, chemicals that act as powerful antioxidants.
Epidemiological and human studies have shown varying results. Thirty-one human studies and four reviews were examined. Among five studies reporting on colon cancer, three found an inverse association and one reported a positive association. An inverse association is suggested for urinary bladder cancer in two of two studies. The most comprehensive of these studies supports an inverse association of green tea and stomach cancer.