Called the sunshine vitamin, vitamin D is formed naturally in the skin by exposure to sunlight. But when an individual does not get enough sun exposure, their body cannot make sufficient vitamin D. Vitamin D supplementation is especially important because it’s hard to get enough during our long, dark northern winters. Vitamin D is a vitamin and hormone that stimulates the body to absorb calcium, and it is needed to keep bones strong. People deficient in vitamin D levels tend to have softer, thin bones, predisposing them to fractures. Vitamin D is especially important for the elderly because of their difficulty synthesizing vitamin D from sunlight as some medications interfere with vitamin D absorption.