Low vitamin D levels may impair thinking

NEW YORK (Reuters Health) - New research suggests that low vitamin D levels in the body are associated with thinking or "cognitive" impairments in older men, but whether vitamin D supplements can help is not yet known.

In the study, an investigation of European men, subjects with low levels of vitamin D scored worse on a standard test of cognitive ability than did their peers with normal levels, Dr. David M. Lee, from the University of Manchester, UK, and co-researchers found. Although, the authors emphasize, the difference in scores was not that great.

Included in the investigation were 3133 men, 40 to 79 years of age, who were enrolled in the European Male Aging Study (EMAS). The average level of 25-hydroxyvitamin D, an inactive form of vitamin D used to measure levels of the vitamin, was 63 nanomoles per liter. Levels of 90 to 140 nanomoles per liter are typically considered optimal.

The researchers report their findings report in the Journal of Neurology, Neurosurgery, and Psychiatry.

As vitamin D levels fell, so did cognitive performance. Further analysis indicated that this relationship was largely confined to men over age 60 and was strongest with vitamin D levels below 35 nanomoles per liter.

While the magnitude of the association was small, Lee and colleagues note, if a simple measure, such as vitamin D supplementation, could improve cognition, then the findings could have important public health implications.

SOURCE: Journal of Neurology, Neurosurgery, and Psychiatry, May 21, 2009 online issue.