Reporting in the Journal of the National Cancer Institute Dr. Walter Willett of Harvard University provided data to suggest that as much as 75% of prostate cancer is avoidable by dietary influences. Considering that prostate cancer is the most frequently diagnosed cancer among U.S. and Canadian men and the second leading cause of cancer death, researchers are actively investigating nutritional agents that can minimize risk of this common degenerative disease.
Within the category of vitamins and vitamin-like compounds that may reduce risk of prostate cancer according to recent evidence, are vitamin D, vitamin E, lycopene (a compound related to beta-carotene and vitamin A) and selenium.
For instance, a recent report demonstrated that men with low blood levels of vitamin D had a significantly higher risk of prostate cancer development. Important advances in understanding how to suppress prostate cancer development appears to involve the role of vitamin D and its effects on regulating prostate cell maturation and cell division rate (differentiation and proliferation).
Prostate cancer cells are known to have vitamin D receptors and vitamin D has been shown to significantly inhibit the growth of prostate cancer under clinical and experimental conditions. The same is true in rat studies using a synthetic vitamin A analogue (N-4-hydroxyphenyl-retinamide). The importance of controlling and regulating the growth and replication rate of prostate cells is the most likely mechanism that vitamin D may reduce prostate cancer development. Further research is underway to better understand this relationship. In the meantime I suggest that healthy adult men ensure that they are ingesting 1000I.U. to 2,000 I.U. of vitamin D per day as part of a vitamin and mineral support.
Another proposed mechanism for the development of prostate cancer involves free radicals. A number of studies suggest a link between free radicals (oxidative stress) and tumor development in various tissues.
In several studies higher intake and/or blood levels of the antioxidants vitamin E and Lycopene have been associated with a decrease in prostate cancer incidence. Vitamin E and Lycopene are capable of quenching free radicals thereby minimizing their ability to damage genetic material (DNA), enzymes and other cellular components.
As pointed out by Olson and Pienta, vitamin E has the potential to decrease DNA damage and inhibit malignant transformation through its antioxidant function. Additionally, Vitamin E affects the immune system; decreased vitamin E is associated with decreased immune response while high levels exert a stimulatory effect on immune function.
In the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, long-term supplementation with vitamin E was associated with a 32% decrease in the incidence of prostate cancer compared with those not receiving vitamin E supplementation. Moreover, death from prostate cancer was 41% lower among men receiving the vitamin E supplement. The length of this supplementation study was 5-8 years and the dosage of vitamin E was 50 mg (alpha-tocopherol).
Previous studies have observed that low blood levels of vitamin E in smokers are associated with an increased risk of prostate cancer.
Many researchers believe that antioxidant function is an important means to prevent prostate cancer initiation and promotion. This contention is further supported by the work of Clark et al. who demonstrated that supplementation with the mineral selenium (mean time period 4.5 years) was associated with a 63% lower incidence of prostate cancer. Selenium has indirect antioxidant properties of its own. The Health Professionals Follow-up Study also supports the hypothesis that antioxidant function can prevent prostate cancer. In this study of nearly 48,000 subjects Giovannucci et al. reported that a significant decrease in risk of developing prostate cancer was associated with of lycopene. Lycopene is found in tomatoes and certain tomato products and is known for its potent antioxidant properties.
Lycopene is the most effective quencher of singlet oxygen (a very aggressive and harmful free radical) of the major carotenoids (beta-carotene-like compounds) and is the primary carotenoid in the blood and various tissues, including the prostate gland.
An intake level of at least 6 mg per day or more of lycopene was associated with approximately a 21% reduction in prostate cancer incidence in The Health Professionals Follow-up Study, compared with men consuming less than 2.3 mg per day.
Taken together the emerging research appears to suggest that vitamin D and the antioxidants vitamin E, selenium and lycopene may significantly reduce the risk of prostate cancer and premature death. Dietary interventions including these nutrients may well hold part of the answer to reducing the risk of this common disease.
Prostate cancer is the most common cancer in males in North America. As part of a good chemo-preventive program to reduce the risk of developing this disease, healthy male adults should consider a multiple vitamin that contains 400 I.U.of vitamin D, 400 I.U. of vitamin E, 200 mcg. of selenium and 6 mg. of lycopene extract.
Be advised that other nutritional factors may also help to prevent prostate cancer and are discussed in other review papers within this site.
Copyright 1998 Dr. James Mescino D.C., M.S., N.D.
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