Consumers are already flocking in for vitamin D to strengthen bones and boost circulatory health, but now they may start turning to the nutrient for brain health. Research published in the May issue of the Journal of Neurology, Neurosurgery, and Psychiatry showed that low vitamin D levels were linked to lower cognitive function. Among 3,133 men ages 40 to 79, those with the lowest vitamin D levels -- particularly men over age 60 -- experienced greater risk of thinking impairment. The researchers did not study whether supplementation with the vitamin improved cognition. Vitamin D has also been shown to aid longevity and prevent colon cancer recurrence.