Selenium and Vitamin E Supplements Increase Risk of Prostate Cancer

Hand Full of SupplementsMen with high levels of selenium who begin taking high doses of selenium and vitamin E supplements may increase their risk of prostate cancer, suggests a new study recently published in the Journal of the National Cancer Institute.

Selenium is a mineral that plays a key role in reproduction, thyroid hormone metabolism, and DNA syntheses and protects against oxidative damage and infection. The nutrient is naturally found in foods such as nuts (Brazil nuts, walnuts), fish (tuna, cod, red snapper, herring), beef and poultry, and grains. The recommended daily dosage of selenium is 55 micrograms per day for individuals over the age of 14.

Vitamin E is fat-soluble vitamin found in many foods including vegetable oils, cereals, meat, poultry, eggs, fruits, vegetables, and wheat germ oil. Vitamin E is an important vitamin required for the proper function of many organs in the body. The vitamin also provides antioxidative benefits.

Previous research on selenium has suggested that men with adequate levels of the mineral will not benefit from additional supplementation.

For the present study, researchers led by Dr. Alan Kristal of the Public Health Sciences Division of the Fred Hutchinson Cancer Research Center in Seattle, Washington investigated the effects of selenium and vitamin E supplementation conditional upon baseline selenium status. The researchers analyzed 1,739 patients with prostate cancer and 3,117 matched controls from the Selenium and Vitamin E Cancer Prevention Trial (SELECT).

Although the study originally sought to determine whether selenium and vitamin E supplements reduced the risk of prostate cancer, the researchers discovered that men with high selenium levels at the beginning of the study who took selenium and vitamin E supplements had a 91 percent increased risk of high-grade prostate cancer.

Men with adequate levels of selenium who take additional selenium supplements increase their selenium levels to toxic levels.

Additionally, men with low selenium levels at the beginning of the study who took vitamin E supplements experienced a 63 percent increased total prostate cancer risk and a 111 percent high-grade prostate cancer risk.

Comments Dr. Kristal:

“Many people think that dietary supplements are helpful or at the least innocuous. This is not true. We know from several other studies that some high-dose dietary supplements – that is, supplements that provide far more than the daily recommended intakes of micronutrients – increase cancer risk. We knew this based on randomized, controlled, double-blinded studies for folate and beta carotene, and now we know it for vitamin E and selenium.”

Individuals taking vitamin E or selenium supplements should stop because the use of both supplements does not provide any clear benefits but does increase the risk of many health problems.

Adds Dr. Kristal, “Taking a broad view of the recent scientific studies, there is an emerging consistency about how we think about optimal intake of micronutrients. There are optimal levels, and these are often the levels obtained from a healthful diet, but either below or above the levels there are risks.”

Individuals should obtain vitamins, minerals, and other nutrients naturally through foods rather than relying on supplements.

Another recent study suggested that vitamin E and vitamin C supplements may hinder athletic training.


Baseline Selenium Status and Effects of Selenium and Vitamin E Supplementation on Prostate Cancer Risk:
Selenium and Vitamin E Supplements ‘Increase Prostate Cancer Risk’:

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