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07-06-2011 | Cardiometabolic | Article

Selenium supplementation shows ‘modest benefits’ in older adults

Abstract

Free abstract

MedWire News: Daily supplementation with selenium may have beneficial effects on plasma lipid levels in older adults, results from a UK study suggest.

Selenium supplementation was associated with modest reductions in total and non-high-density lipoprotein (nonHDL) cholesterol levels, and, at higher doses, with increases in HDL cholesterol levels, say Margaret Rayman (University of Surrey, Guildford) and colleagues.

They add that previous studies have found conflicting evidence about the effect of selenium status on plasma lipids and heart disease.

For the current study, the team randomly assigned 501 volunteers, aged 60-74 years, to one of four treatment groups: selenium 100 mcg (n=127), 200 mcg (n=127), or 300 mcg (n=126) daily, or a yeast-based placebo (n=121). Measures for total and HDL cholesterol concentrations were available for 454 participants at baseline and 394 at 6 months.

The mean plasma selenium concentration was 88.8 ng/g at baseline, which, the authors note, is relatively low. However, selenium levels significantly increased across all treatment groups, reaching 143.9, 188.1, and 225.4 ng/g in the selenium 100, 200, and 300 mcg/day groups, respectively, after 6 months of treatment.

Increasing plasma selenium levels were significantly associated with increasing total and HDL cholesterol levels, and with a decreasing total/HDL cholesterol ratio.

For example, the adjusted mean differences in change in total cholesterol levels for selenium compared with placebo were -0.22, -0.25, and -0.07 mmol/l (-8.49, -9.65, and -2.70 mg/dl) in the selenium 100, 200, and 300 mcg/day groups, respectively. Of note, the difference in the 300 mcg/day group did not reach statistical significance.

Similar reductions were observed for nonHDL cholesterol levels and the total/HDL cholesterol ratio decreased progressively with increasing selenium dose.

For HDL cholesterol, there were no significant differences in change in the selenium 100 and 200 mcg/day groups compared with placebo, but treatment with selenium 300 mcg/day resulted in a significant adjusted change of 0.06 mmol/l (2.32 mg/dl).

Writing in the Annals of Internal Medicine, the researchers caution that the clinical significance of their findings is "unclear," and "should not be used to justify the use of selenium supplementation as additional or alternative therapy for dyslipidemia."

They add that "this is particularly true for persons with higher selenium status," given the "relatively low" selenium status of the study population.

"Further clinical trials are needed to corroborate our findings," they conclude.

MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Nikki Withers