[Read the Article] About 42 percent of the general U.S. population has low vitamin D levels. In addition to promoting calcium and bone health, vitamin D may also affect the brain and cognitive function. A new study by JAMA Neurology looked at the association between baseline vitamin D levels and the rate of cognitive decline in a group of ethnically diverse older adults. A researcher from Rutgers University, along with colleagues from the University of California Davis, studied 382 older adults with an average age of 75. Among the group, 61 percent of participants were women, 41 percent white, about 30 percent were African American and 25 percent were Hispanic. At study enrollment, about 18 percent had dementia, 33 percent had mild cognitive impairment and half were cognitively normal. Vitamin D levels and cognitive function were measured at baseline. Cognitive function was also followed in 318 of the participants for an average of 5 years. Researchers found:- About 60 percent of the group, regardless of their race or ethnicity, was low in vitamin D.- Vitamin D levels were lower for African American and Hispanics, compared with their white counterparts.- ...