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Selenium for age-related cognitive decline.

Thirty-one elderly Brazilian individuals (mean age, 78 years) who had mild cognitive impairment were randomly assigned to consume 1 Brazil nut per day (providing daily an estimated 289 [micro]g of selenium) or no Brazil nuts for 6 months. At baseline, the serum selenium concentration was below normal in all but 1 participant. Twenty individuals completed the trial. Serum selenium levels increased in the Brazil nut group but not in the control group. After 6 months, improvements in verbal fluency (p = 0.007) and constructional praxis (p = 0.03) were significantly greater in the Brazil nut group than in the control group.

Comment: Brazil nuts are among the richest dietary sources of selenium. In the present study of elderly individuals with low serum selenium levels and mild cognitive impairment, consumption of 1 Brazil nut per day for 6 months had a positive effect on certain measures of cognitive function. Although Brazil nuts contain many nutrients other than selenium, the amounts present in 1 nut are presumably not sufficient to produce a measurable effect on cognitive function. Therefore, the improvements observed in this study are probably due to the selenium.

The selenium content of the Brazil nuts used in this study was analyzed by flame atomic absorption spectrometry, but according to other sources, the selenium content of Brazil nuts is much lower (50-80 [micro]g per nut). Because of these discrepancies, it is not clear how many Brazil nuts one should consume if the goal is to improve selenium status without risking selenium toxicity. Therefore, it may be better to use selenium supplements than to consume an unknown amount of selenium from Brazil nuts.

Rita Cardoso B et al. Effects of Brazil nut consumption on selenium status and cognitive performance in older adults with mild cognitive impairment: a randomized controlled pilot trial. Eur J Nutr. Epub 2015 Jan 8.

by Alan R. Gaby, MD

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Title Annotation:Literature Review & Commentary
Author:Gaby, Alan R.
Publication:Townsend Letter
Article Type:Brief article
Date:Oct 1, 2015
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