What is Vitamin D and what does it do? Vitamin D is a nutrient found in some foods that is needed for health and to maintain strong bones. It helps the body to absorb calcium (one of bone’s main building blocks) from food and supplements. People who get too little Vitamin D may develop soft, thin and brittle bones, a condition known as rickets in children and osteomalacia in adults. Vitamin D is important for our body in many ways….