SELENIUM & PROSTATE CANCER
Key points:
- Eskimo/Inuit men in Greenland have the among the highest Se and omega-3 fatty acid intakes in the world (resulting in blood plasma Se levels commonly around 2000 µg/l, compared with South Australian levels of around 100 µg/l), and the lowest prostate cancer rates (whether early [microfocal] or advanced prostate cancer) in the world (Dewailly et al, 2003).
- Se’s strongest anti-cancer effect in the US Nutritional Prevention of Cancer Trial was against prostate cancer, where a 52% reduction in incidence was observed (Duffield-Lillico et al, 2002).
- Oxidative stress may enhance prostatic carcinogenesis. A mutation of the gene for manganese superoxide dismutase, the major antioxidant enzyme in mitochondria, has been studied. Men with the AA (aberrant) genotype who were in the bottom 25% for Se, vitamin E & lycopene intake combined, had a 10-fold higher risk for aggressive prostate cancer than AA men in the highest 25% for these nutrients (Li et al, 2005). [Link to the Article Abstract]. Supplementation with the same three nutrients in a mouse prostate cancer model study dramatically inhibited prostate cancer development (Venkateswaran et al, 2004).
- Numerous studies show associations between low Se status and increased risk of prostate cancer, particularly advanced prostate cancer. For example, in the Baltimore Longitudinal Study on Aging, low Se status was associated with a 4-fold increase in prostate cancer risk (Brooks et al, 2001).
- Smoking appears to be a risk factor for advanced prostate cancer. A US study found that the risk of advanced prostate cancer increased with increasing cumulative smoking in the 10 years before surgery in men younger than 55 years (Roberts et al, 2003). Another study found that Se/cadmium (cadmium is a carcinogen) ratio fell more steeply and consistently with age in smokers than in nonsmokers (Drasch et al, 2005).
- Dietary factors cause between 10 and 80% of cancers, depending on the type of cancer, and prostate cancer is at the upper end of this scale. Anti-prostate cancer dietary/exercise recommendations (from Graham Lyons B Agric Sci, M Public Health, PhD, nutrition and cancer preventive researcher, University of Adelaide): Eat a varied diet that includes a range of fruit (including apples and berries), vegetables (including broccoli, carrots, onions, beetroot, tomatoes, spinach, avocadoes), whole grain, legumes, fish and lean meat. Cook with olive oil, drink 1-2 glasses of wine (preferably red) per day, and don’t overeat…limit your total caloric intake. And importantly: get plenty of exercise (30-45 minutes of vigorous activity that increases the heart rate appreciably, per day…including some aerobic work and light weights). Don’t smoke. Limit your intake of dairy products and fatty meat. NB: in addition to the supplements listed below, I recommend supplementary magnesium (around 300 mg/day) and B-vitamins for most adults. The “A Team” comprises those supplements with the strongest evidence for anti-prostate cancer effect (in terms of prevention, and, in most cases, inhibition of cancer progression as well) at the present time. The “B Team” members may be effective and some may soon be promoted to the top team, but they need a stronger evidential base at this stage.
A Team: Selenium; vitamin E (both alpha- and gamma-tocopherol); lycopene (the red carotenoid in tomatoes; tomato paste is a rich source); green tea polyphenols; soy polyphenols; omega-3 fatty acids (DHA & EPA); resveratrol (from grapeseed & red wine); beta-sitosterol (from the Saw Palmetto palm); vitamin C (best as calcium or sodium ascorbate); vitamin D3 (from sunlight & cod liver oil).
B Team: Boron (avocadoes, nuts, boric acid); Epilobium (Willow herb); aspirin (one-third tablet/day); Pau d’Arco (South American tree bark herbal preparation); beta-glucan (from the Shiitake mushroom); phytate (in legumes & whole grain cereals); curcumin (from turmeric); alpha-lipoic acid (a thiol); gamma-linolenic acid (from borage, blackcurrant seed, Evening Primrose oil); coenzyme Q10; dark chocolate (about the highest antioxidant capacity of any food).
References
Brooks JD, Metter EJ, Chan DW, Sokoll LJ, Landis P, Nelson WG, Muller D, Anres R, Carter HB 2001. Plasma selenium level before diagnosis and the risk of prostate cancer development. J Urol 166: 2034-2038.
Dewailly E, Mulvad G, Pedersen HS, Hansen JC, Behrendt N, Hansen JPH 2003. Inuit are protected against prostate cancer. Cancer Epidemiol Biomarkers Prev 12: 926-927.
Drasch G, Schopfer J, Schrauzer GN 2005. Selenium/cadmium ratios in human prostates: indicators of prostate cancer risk of smokers and nonsmokers, and relevance of the cancer protective effects of selenium. Biol Trace Elem Res 103(2): 103-108.
Duffield_Lillico AJ, Reid ME, Turnbull BW, Combs GF, Slate EH, Fischbach LA, Marshall JR, Clark LC 2002. Baseline characteristics and the effect of selenium supplementation on cancer incidence in a randomized clinical trial: a summary report of the Nutritional Prevention of Cancer Trial. Cancer Epidemiol Biomarkers Prev 11: 630-639.
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