Prostate cancer is a disease in which malignant (cancer) cells form in the tissues of the prostate.
The prostate is a gland in the male reproductive system. The prostate is just below the bladder (the organ that collects and empties urine) and in front of the rectum (the lower part of the intestine). It is about the size of a walnut and surrounds part of the urethra (the tube that empties urine from the bladder). The prostate gland produces fluid that makes up part of the semen. Anatomy of the male...
Catechins are polyphenol compounds in tea that are associated with many of tea's proposed health benefits.
Epigallocatechin gallate (EGCG), the most abundant catechin in tea, acts as an androgen antagonist and can suppress prostate cancer cell proliferation, suppress production of prostate-specific antigen (PSA) by prostate cancer cells, and increase prostate cancer cell death in vitro.
Results from one in vitro study showed that prostate cancer cells were less susceptible to radiation -induced apoptosis when exposed to EGCG 30 minutes before radiation exposure.
Oral intake of either a green tea catechin solution or EGCG alone was associated with reduced development of prostate cancer in studies with transgenic adenocarcinoma of the mouse prostate (TRAMP) mice.
Epidemiologic studies of Japanese men have generally not shown a relationship between reported green tea consumption and prostate cancer development, but at least one study has shown an association with the development of advanced prostate cancer.
Results from a small placebo-controlled study of green tea catechins in men with high-grade prostatic intraepithelial neoplasia (HGPIN) showed a statistically significant decrease in the development of prostate cancer among men who were randomly assigned to receive the catechin supplement. A larger, multicenter, randomized trial is now under way.
Studies of orally administered mixtures of tea catechins in men with prostate cancer have begun to provide information about biologic effects in this setting but are too preliminary to draw conclusions about clinical effectiveness.
Green tea has been well tolerated in clinical studies of prostate cancer patients, with the most common side effects being mild gastrointestinal symptoms.
General Information and History
Sailors first brought tea to England in 1644, although tea has been popular in Asia since ancient times. After water, tea is the most consumed beverage in the world. All tea originates from the C. sinensis plant, and the methods by which the leaves are processed determine the type of tea produced. To make green tea, the leaves are steamed and dried; this type of processing results in minimal oxidation, and the compounds in the tea are stabilized. Black tea is produced by crushing tea leaves to encourage enzymatic oxidation. Oolong, the third major type of tea, contains polyphenols that are partially oxidized.
Some observational and interventional studies suggest that green tea may have a protective effect against cardiovascular disease, and there is evidence that green tea may protect against various forms of cancer. Many of the health benefits associated with tea have been attributed to polyphenols. Catechins compose most of the polyphenols found in tea; of these, epigallocatechin-3-gallate (EGCG) has been the most widely researched.