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Among the vitamins, vitamin D is unique because the body can make enough to satisfy its needs. This requires adequate nutritional status and external conditions, (such as sun exposure). Otherwise, vitamin D is also available from supplements and some food sources.

Compared to most vitamins, relatively few foods naturally contain significant amounts of vitamin D. Cod liver oil and fatty fish (including salmon, mackerel and tuna) are among the few sources that provide large amounts. Small quantities are also found in eggs, cheese and liver. Other dietary options include fortified foods, such as milk and margarine, which have inactive forms of vitamin D added during processing. For vegans and others who avoid eating animal products, fortified breakfast cereals and fruit juices are also available.

For many people, sunlight provides most or all the vitamin D the body needs and dietary intake is less important. For light-skinned people, exposing the arms and legs for about 10 minutes a day may provide sufficient vitamin D. The amount of exposure required increases with darker skin color, due to higher levels of the skin pigment melanin. In addition, the skin’s ability to produce vitamin D diminishes with age, and people living in the northern areas of the United States do not get adequate sunlight to produce vitamin D in the winter.

Under certain conditions a physician may recommend supplements. Vitamin D is available individually, coupled with calcium or as part of many multivitamins. It’s best to check with your doctor before taking vitamin D supplements due to the health risks that may occur if you take too much over a period of time.