Vitamin D plays an important role in maintaining bone health, but a new study led by University of Kentucky researchers claims that deficiency of this vitamin may cause damage to the brain and other organs. The results, published in Free Radical Biology and Medicine, showed that when middle-aged rats were fed a diet low in Vitamin D for several months, they developed free radical damage to the brain. They also performed less well in cognitive functioning tests for learning and memory. The researchers say that several brain proteins were found to have significantly higher levels and that this contributes to significant nitrosative stress in the brain, possibly leading to cognitive decline.