Vitamin D’s main job is to maintain normal blood levels of calcium and phosphorus. Vitamin D aids in the absorption of calcium, helping to form and maintain strong bones. It’s also known as the “sunshine vitamin,” because the body manufactures the vitamin after being exposed to sunshine. Ten to 15 minutes of sunshine 3 times weekly is enough to produce the body's requirement of vitamin D, and it’s also found in foods such as fortified milk, eggs, butter, margarine, herring, salmon, and fish liver oils. Vitamin D deficiency can lead to osteoporosis in adults and rickets (a disease of bone softening, particularly in the legs) in children.