Selenium Keeps Aging Muscles Strong
September 6, 2007—Low selenium levels are associated with muscle weakness in seniors, according to a recent study published in the American Journal of Clinical Nutrition.
Selenium is a trace mineral known for its antioxidant nature and its antiviral and anticancer properties. Garlic, Brazil nuts, sesame seeds, legumes, fish, meat, and poultry are rich in selenium, but the amount depends on how much is in their environment or the soil in which they are grown. Selenium deficiency is more common in areas known to have selenium-poor soil, such as the Pacific Northwest. The mineral is increasingly stripped from the soil by modern agricultural practices.
Selenium’s antioxidant effects help protect muscles from oxidative damage, one of the factors that contributes to the loss of strength that generally occurs with age. Severe selenium deficiency can cause damage to both skeletal and heart muscles, but less is known about milder deficiency.
The new study included 891 men and women age 65 and older who lived in their communities and not in nursing homes. Researchers measured their blood selenium levels and tested their muscle strength by looking at hip flexion, knee extension, and hand grip.
After noting that 30% of the men and women had suboptimal selenium levels, the researchers divided them into four groups based on how much selenium they had in the blood. People with the highest levels had the greatest upper and lower body strength, performing better on hip, knee, and hand strength tests. People with the lowest selenium levels were 1.5 to 2 times as likely as people in the highest group to be in the lowest range for muscle strength.
“To our knowledge, this is the first study to show an association between plasma selenium concentrations and poor muscle strength in older adults,” the study authors stated. “These results suggest that there may be a continuum in the relation between plasma selenium concentrations and muscle strength, from those with severe selenium deficiency and muscle weakness to community-dwelling older adults with marginal selenium concentrations.”
During six years of follow-up, those with the lowest selenium levels and weakest muscles were found to be the least likely to survive. This finding is consistent with those from previous studies linking both muscle weakness and low selenium levels to increased mortality.
The US Recommended Dietary Allowance for selenium is 55 mcg per day, but supplementing with up to 200 mcg per day is generally considered to be safe. Dr. Luigi Ferrucci, at the National Institute on Aging in Baltimore, and one of the coauthors of the study, advises people to check their multivitamins before adding selenium supplements, noting that “most multivitamin–mineral preparations used by the older population already contain selenium.”
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(Am J Clin Nutr 2007;86:347–52)
Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, VT, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.
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