Vitamin D exists in several different types, but the two most famous is ergokalsiferol (vitamin D2) and cholecalciferol (vitamin D3). These were previously thought to have the same biological effect. But recent research shows that vitamin D3 has a greater biological aktivetet The form that occurs commonly in humans is cholecalciferol, since it is this that forms the skin and found in animal foods (eg. Oily fish and cod liver oil).
Vitamin D can be supplied to the body through the oily fish (mackerel, herring, halibut, trout, salmon) and fish liver. Butter and margarine and a few milk types are usually enriched with vitamin D so that these also are good sources. If the body is not supplied enough vitamin D through diet, supplements can be used as fish oil, capsules of vitamin D or multivitamin tablets.
The recommended intake is 7.5 micrograms a day for children aged two years and adults up to sixty years. For children up to two years and older than sixty years, the recommended intake 10 micrograms a day. Proffesional athletes and others with a very active lifestyle usually consume x2-x4 this amount with the help of specialized diet and Vitamin D Supplements.