Vitamin D is a fat-soluble vitamin most notably known for its protective effects on bone. Vitamin D has been used for building bone mass and preventing bone loss, protecting against muscle weakness and promoting strong teeth. It is also used for preventing rickets and postmenopausal osteoporosis. Interestingly, very few foods naturally contain Vitamin D. Some dietary sources include eggs from chickens that have been fed Vitamin D and fatty fish such as herring, mackerel, sardines and tuna. We acquire most of our Vitamin D from daily exposure to sunlight.