Sources of Vitamin D

Vitamin D is sometimes called the "sunshine vitamin" because your skin can make it when exposed to sunlight. It plays an essential role in helping the body absorb calcium, which is why it is so important for strong bones and teeth. Vitamin D also supports muscle function and the immune system. Yet many people do not get enough — making it worth knowing where this nutrient actually comes from and how to keep your levels healthy.

This article is for general education only and is not a substitute for professional medical advice. Do not start high-dose supplements without guidance; ask your healthcare provider whether testing or supplementation is right for you.

Why Vitamin D Matters

Without enough vitamin D, the body cannot absorb calcium efficiently, no matter how much calcium you eat. Over the long term, a shortfall can weaken bones — causing rickets in children and contributing to bone-thinning conditions in adults. Adequate vitamin D, paired with calcium, is one of the foundations of lifelong bone health.

Sunlight: The Body's Own Supply

When sunlight reaches the skin, it triggers vitamin D production. The amount made depends on the season, time of day, latitude, skin tone and how much skin is exposed. People who spend most of their time indoors, live in northern climates, or cover their skin may make less than they need from sun alone — which is where food and, sometimes, supplements come in. Sensible sun exposure should always be balanced against skin-cancer risk.

Food Sources of Vitamin D

Relatively few foods are naturally rich in vitamin D, which is why fortified foods are important. Good dietary sources include:

Fatty fish such as salmon, mackerel, sardines and trout
Fish-liver oils
Egg yolks and some mushrooms exposed to ultraviolet light
Fortified foods — many milks, plant-based drinks, breakfast cereals and some juices have vitamin D added

Reading nutrition labels makes it easier to spot fortified products and build them into the kind of varied diet described in nutrition basics.

When a Supplement May Help

For people who get little sun and few vitamin-D-rich foods — including some older adults, those who are housebound, and people with certain medical conditions — a supplement can help close the gap. More is not always better, however: very high doses over time can be harmful. A blood test can show whether your level is low, and your healthcare provider can recommend an appropriate amount.

Authoritative Resources

For more on vitamin D, see the NIH Office of Dietary Supplements fact sheet, MedlinePlus on vitamin D, and the NIH bone-health nutrition resources.

Related reading: Nutrition Basics, Dietary Fiber and Why It Matters, and Eating for a Healthy Heart. Return to the health article index.