Selenium: Supplements, What Works
Selenium is a trace mineral that has been the subject of extensive research and controversy. Found in brown rice, seafood, enriched white rice, whole-wheat flour, and Brazil nuts, it is a powerful antioxidant, and is also a component of glutathione peroxidase, an antioxidant enzyme that helps to protect against free radical damage.
Much of the world's soil is deficient in selenium, which leads to low selenium intake. According to epidemiological studies, this accounts for an increased risk in certain regions of many kinds of cancer, including breast and colon cancer, and increased heart disease in certain regions. For example, people in selenium-depleted north-central China suffer some of the world's highest rates of esophageal and stomach cancer. However, these rates declined when some inhabitants were given selenium and vitamin E.
People need very little selenium to protect their health. For men, the RDA is 70 mcg (micrograms, or millionths of a gram), and for women it is 55 mcg. Many authorities now advise 200 to 400 mcg per day. However, 700 to 800 mcg a day may be toxic. Chronic ingestion of 5,000 mcg a day has been reported to result in fingernail changes, hair loss, nausea, abdominal pain, diarrhea, nerve problems, fatigue, and irritability. Because vitamin E enhances the effects of selenium, it can increase this possible toxicity.
Among the claims made for selenium are that it protects against cancer, improves immunity, protects against oxidative stress, prevents and treats AIDS-related pathology, and treats infertility. In actuality, though, RCTs present rather sketchy evidence of most of these claims.
Other conditions that showed an inconclusive reaction to selenium were myotonic dystrophy, asthma, and infertility. Also, selenium showed no ability to reduce oxidative stress in children with cystic fibrosis.
People with special antioxidant needs may benefit from moderate selenium supplementation, but most claims about selenium remain unproven.
From THE BEST ALTERNATIVE MEDICINE: WHAT WORKS? WHAT DOES NOT? by Dr. Kenneth R. Pelletier.
Copyright © 2000 by Dr. Kenneth R. Pelletier, Inc.
Reprinted by permission of Simon & Schuster, Inc., New York, New York.
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Dr. Kenneth R. Pelletier. All Rights Reserved.