Common essential mineral may reduce the risk of some cancers
Selenium is one of the most promising antioxidant supplements. The essential mineral is crucial for immune and thyroid function, sperm development and activating certain enzymes -- a role that could provide clues as to how it might help prevent cancer. The majority of people in the U.S. don’t have trouble getting enough to stay healthy; the mineral is found in most plant foods and nuts, as well as animal products and seafood. Tuna, eggs, wheat germ, chicken, liver, garlic and Brazil nuts are all particularly good sources. Selenium deficiency (common in people with HIV) has been linked to asthma, anxiety, depression, arthritis, heart disease and pregnancy complications.
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Uses: Selenium supplements are taken in efforts to prevent and treat cancer, particularly prostate, lung and colon cancer. They’re also taken to improve immune function and heart health.
Dose: The Food and Drug Administration recommends about 70 micrograms a day for adults and children older than 4; most people in the U.S. get close to 100 micrograms per day. In most studies examining selenium’s effect on cancer risk, subjects took up to 200 micrograms per day.
Precautions: Taking high doses (hundreds or thousands of micrograms or more a day) over a long period of time can cause nausea, bad breath, dizziness, weakness, rash and cold symptoms. Pregnant women should limit their selenium intake to no more than 60 micrograms a day to avoid increasing their risk of complications such as miscarriage.
Research: Several human studies suggest that selenium may reduce the risk of lung, colorectal, gastrointestinal and bladder cancer, but at least one study suggests it may increase the risk of certain types of skin cancer. A recent study suggested that selenium may be more effective at preventing cancer in men than in women. The mineral seems most promising in reducing the risk of prostate cancer. According to one study, men with low selenium intake had four times higher risk of developing prostate cancer than those who got enough of the mineral. The National Cancer Institute is sponsoring a study of more than 35,000 men in the U.S., Canada and Puerto Rico to determine whether selenium can help prevent prostate cancer. Final results aren’t expected for several years.
Dietary supplement makers are not required by the U.S. government to demonstrate that their products are safe or effective. Ask your healthcare provider for advice on selecting a brand.
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-- Elena Conis
