A recent study involving 2,000 rural Chinese people aged 65 years or more suggests that low levels of selenium throughout life are associated with lower cognitive function in old age. Scientists collected nail samples and analyzed them for selenium levels. Cognitive function was assessed based on scores in a variety of clinical testing methods. The researchers found that lower nail sample selenium levels were significantly associated with lower cognitive scores.
Source: Am J Epidemiol. 2007 Apr 15;165(8):955-65
