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Selenium and vitamin E supplements may increase risk of prostate cancer

Harold Mandel's picture
Health check

Contrary to popular belief selenium and vitamin E supplements do not appear to prevent prostate cancer, and may instead increase the risk of prostate cancer. As men age concerns about being hit with prostate cancer heighten. Therefore, the search for safe and effective natural interventions to prevent this dreaded cancer are anticipated. It has been suggested over the years that selenium and vitamin E may help prevent prostate cancer, but recent research shows to the contrary these supplements may increase the risk for prostate cancer.

The researchers have concluded selenium supplementation did not benefit men who had low selenium status but increased the risk of high-grade PCa among men who had high selenium status, reported the Journal of the National Cancer Institute. Vitamin E was found to increase the risk of PCa among men with low selenium status. It is therefore advised that men should avoid selenium or vitamin E supplementation at doses which exceed recommended dietary intakes.

Selenium and vitamin E supplements have been found to increase the risk of prostate cancer in some men, reports the Fred Hutchinson Cancer Research Center in a discussion of this research.

It has been found in a multi-center study which was led by Fred Hutchinson Cancer Research Center that high-dose supplementation with both the trace element selenium and vitamin E increase the risk of high-grade prostate cancer. It is significant to note that this risk depends upon a man’s selenium status prior to taking the supplements.

This study was originally intended to determine whether taking high-dose vitamin E and/or selenium supplements could protect men from prostate cancer. The study began in 2001 and was intended to last 12 years. The study was however stopped early in 2008 because no protective effect from selenium was observed, and there was a suggestion that vitamin E actually increased risk.The men who took vitamin E were found to have a statistically significant 17 percent increase in the risk of prostate cancer.

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Selenium supplementation was found to increase cancer risk in men who had a high selenium status at baseline. At the genesis of the study there was some evidence that selenium supplementation would not actually benefit men who already had an adequate intake of the nutrient. Therefore, the researchers measured the concentration of selenium in participants’ toenails and they planned to test whether selenium supplementation would serve to benefit only the subset of men with low selenium status at baseline.

What the researchers found was taking selenium supplements increased the risk of high-grade cancer by 91 percent among men with high selenium status at baseline. Therefore, if men who had high selenium status to begin with, selenium supplements caused the levels of selenium to become toxic.

It was also observed in this study that only a subgroup of men was at increased risk of prostate cancer from taking vitamin E. Among men who had a low selenium status at baseline, vitamin E supplementation increased their total risk of prostate cancer by 63 percent and increased the risk of high-grade cancer by 111 percent. First author Alan Kristal, Dr.P.H., a faculty member in the Public Health Sciences Division of Fred Hutchinson, has said, “Many people think that dietary supplements are helpful or at the least innocuous. This is not true.”

Kristal has pointed out that other studies show that some high-dose dietary supplements, which refers to supplements that provide far more than the daily recommended intakes of micronutrients, increase cancer risk. This was known based on studies for folate and beta carotene, and now we know this is also true for vitamin E and selenium. The bottom line is the study demonstrated no benefits to any men from either selenium or vitamin E supplements, and for a significant proportion of men in the study these supplements were harmful.

It is the position of these researchers that men who are using these supplements should simply stop. In view of the findings in this research this is clearly good advice. It appears it will be hard to break down the myth that these supplements beyond a doubt are beneficial in the fight against prostate cancer. Therefore, the findings in this study should be shared with patients. There appears to be no risks from taking a standard multivitamin, while the effects of high-dose single supplements
have been found to be unpredictable, complex and even harmful. It is important to advise patients that a healthy diet is essential for good overall health, but that mega doses of supplements may not be very healthy.

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