Vitamin D is the most important nutrient for both your bones and teeth. There are actually two forms of Vitamin D that are crucial for proper nutrition, known as Vitamin D2 and Vitamin D3. Vitamin D2 often comes from foods such as cereal and milk. Vitamin D3 is actually synthesized by your body when exposed to sunlight, and is also found in eggs, salmon, tuna, and mackerel. Vitamin D is not only important for nutrition, abnormal levels of Vitamin D can result in bone disorders, nutrition problems, organ damage, and other medical conditions. Nearly half the U.S. population is Vitamin D deficient.