The document discusses vitamin D, including that it is vital for healthy teeth and bones by promoting calcium absorption, daily requirements are 5-20 mcg depending on age, and the main source is sunshine. However, vitamin D is also found in some foods like fatty fish and fish liver oils, as well as fortified milk, cereal and supplements. The history of vitamin D research shows it was found to prevent rickets and many countries instituted fortifying foods like milk to increase intake.