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Selenium's Secrets Probed

A study of selenium, under way in northern California, may reveal important clues about the role of this essential nutrient in the human body. The research will help determine whether tomorrow's breads, pastas and other flour-based foods should be fortified with selenium to boost health. That's according to research chemist Chris Hawkes of the ARS Western Human Nutrition Research Center at Davis, Calif.

Hawkes is leading the study and is collaborating with investigators from the Nutrition Center, the University of California at Davis School of Medicine and Medical Center and the University of California at San Francisco.

The researchers are scrutinizing selenium's effects on the immune, cardiovascular and reproductive systems and on body composition--that is, the relative amount of fat-to-lean tissue such as muscle. They’re doing that by regularly testing more than 30 healthy men, aged 18 to 45, who have volunteered for the investigation. The study eventually will encompass 48 volunteers.

In the first year of the two-year study, half of the volunteers take a daily capsule that provides five-and-one-half times the Recommended Dietary Allowance of selenium in the form of high-selenium yeast. The other volunteers take a daily placebo, a capsule that looks the same but contains yeast, but no selenium.

At prescribed intervals over the two-year period, volunteers report to the Nutrition Center to give samples of blood and other specimens and to undergo tests. A test of cardiovascular fitness, for example, will indicate whether increasing selenium intake enhances blood flow in arteries. Studies done elsewhere showed that arteries did not properly expand and contract in laboratory animals raised on selenium-deficient feed.

Seafood--and grains and meats from regions with selenium-rich soils--are good sources of this mineral. Other sources include dairy products and vegetables.

The March 2002 issue of the agency's Agricultural Research magazine tells more.

ARS is the U.S. Department of Agriculture's chief scientific research agency.