Selenium is an important mineral that has been extensively studied over the past 20 years. Already recognized as a powerful antioxidant, selenium has been associated with reduced incidence of several types of cancers as well as a stimulant for the immune system. Selenium also appears to protect against cardiovascular disease and to support male fertility. In areas of the United States where selenium soil levels are low, incidence of stroke and cancer are much higher.
Anti-Cancer Effects of Selenium
Evidence has shown that selenium, added to the food or water of laboratory animals, reduced incidences of cancer of the liver, skin, colon and mammary glands. A study on selenium was conducted at Cornell University and its results published in "The Journal of the American Medical Association." Gerald F. Combs Jr., a Cornell professor of nutritional sciences and member of the study team, explained that this was the first placebo-controlled, double-blind cancer prevention study on humans that showed selenium could reduce the risk of cancer.
Researchers at the University of Arizona compiled data from three large clinical trials. Study results published in November 2004 in the "Journal of the National Cancer Institute" found that people with the highest blood levels of selenium had a 34 percent lower risk of abnormal cell growth and developing new polyps in the colon and rectum.
Male Sex Drive and Potency
In a 1998 double-blind study published in the "British Journal of Urology," 69 infertile men with reduced sperm motility were treated with either a placebo, selenium or a combination of selenium with other antioxidants (vitamins A, C and E) for 90 days. At the conclusion of the study, both selenium-treated groups of men noted significant improvements in sperm motility. An interesting side note: 11 percent of the men successfully impregnated their partners during the trial.
Uses
Preventing cellular oxidation with antioxidants is one of selenium's chief uses. Selenium is also attributed with the ability to decrease platelet aggregation (stickiness), which provides further protection against coronary artery disease, heart attack and stroke. There is extensive evidence that selenium plays a role in inhibiting many aging processes and the development of chronic diseases associated with aging, such as arthritis, emphysema, cirrhosis of the liver and arteriosclerosis.
Warning
In spite of its purported benefits, selenium is toxic in high doses and should not be supplemented with a "more is better" approach. Andrew Weil, M.D., director of the Arizona Center for Integrative Medicine and author of "Eating Well for Optimum Health," recommends that adults supplement their diet with 200 mcg selenium per day. A recent study published in the "Journal of Clinical Oncology," conducted at the Dana-Farber Cancer Institute the University of California San Francisco, concluded that high levels of selenium in the blood may worsen prostate cancer in men diagnosed with the disease.
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