Prostate cancer (PCa) is becoming a widespread problem worldwide as our population continues to age. Prevention is increasingly important! As well, early treatment will likely be beneficial since PCa is often slow to progress. Selenium, alpha-tocopheral, isoflavones, lycopene, green tea polyphenols, calcium and resveratrol are proposed beneficial in preventing the progress of PCa.
The lowest rates of this cancer have been found in Japan and throughout Asia. With the increasing use of the Western diet by the Japanese, the risk of PCa has rapidly increased. (The Western diet contains high-fat, high-protein and low-fiber foods with low plant antioxidants, low isoflavones and low polyphenols.) The easiest chemoprevention of PCa is dietary changes or supplements. However, most men seem to prefer taking supplements and resist changing their diets. (Finasteride and dutasteride are current pharmaceutical chemopreventives of PCa which inhibit an enzyme called 5-alpha reductase*.)
Selenium is a trace mineral found in vegetables, grains, red meat, fish, poultry and eggs. Antioxidant enzymes require selenium, selenium has been shown to reduce cancer in general. There is a possibility that selenomethionine may be a better form of selenium, and high selenium yeast needs to be studied for PCa prevention. Genetic factors are involved.
Vitamin E, an antioxidant, is a fat soluble vitamin found in oils (soy, corn, olive) as well as nuts, seeds and green leafy vegetables. Vitamin E is antioxidant, and alpha-tocopherol is the most active form of vitamin E. One study of alpha-tocopherol showed a 32% reduction of PCa on a dose of 50 mg/day.
Genistein, daidzein and glycitein (isoflavones from soy) are plant estrogens which cause apoptosis of PCa cells in vitro. Genistein inhibits PCa at high doses in vivo, but promotes cancer at low doses. Epidemiologic studies support the benefit of isoflavones against PCa.
Lycopene, associated with reduced PCa risk, is a carotenoid that gives red coloring to tomato products, watermelons, pink grapefruit and papayas. Tomato sauce shows very high risk reduction of PCa.
Studies of Asians show that green tea protects from PCa. Polyphenols include chemicals from green tea called catechins. EGCG (epigallocatechin-3-gallate) is a catechin which has been highly studied as an antioxidant and anticancer agent. Green tea catechins have been shown to reduce various lower urinary tract symptoms.
Calcium intake reduces PCa risk in several studies; however high dose calcium studies have shown conflicting results. Resveratrol comes from red wine, grapes, berries, peanuts and dietary supplements. Studies confirm that resveratrol can cause apoptosis of PCa cells.
CONCLUSION: Soy isoflavones, lycopene and green tea polyphenols show promise for chemoprevention of PCa. Some studies of selenium, alpha-tocopheral and lycopene have shown negative results, possibly due to study design. Resveratrol and calcium need appear to need more study.
NOTE: *Kudzu (Pueraria lobata) is a natural 5-alpha reductase enzyme inhibitor. Such products have been shown to be preventive of PCa.