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What Is Vitamin D?

Contributors: Sarah Klemm, RDN, CD, LDN

Reviewers: Academy Nutrition Information Services Team

Published: March 11, 2022

Reviewed: January 10, 2023

What Is Vitamin D?
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Vitamin D is a nutrient needed for health and to maintain strong bones. Vitamin D aids in the absorption of calcium and phosphorus in our bodies, helps bring calcium and phosphorus to our bones and teeth, and helps regulate how much calcium remains in our blood. Together with calcium, vitamin D helps protect against the loss of bone mass.

Vitamin D's importance does not end there. It also helps muscles function and allows the brain and body to communicate through nerves. The immune system also uses vitamin D. There are three ways to get vitamin D: from sunlight, through food and drinks or with supplements.

Vitamin D from the Sun

Your body converts sunlight into vitamin D after it hits unprotected skin — hence the nickname "the sunshine vitamin." However, be careful to avoid extended exposure to sunlight without sunscreen.

Vitamin D from Food and Drinks

Very few foods naturally have vitamin D. Fatty fish such as salmon and trout are among the best sources of vitamin D. Beef liver, cheese and egg yolk provide small amounts. Mushrooms also contain this vitamin if grown under UV lights.

Fortified foods and drinks provide most of the vitamin D in our diets. Most milk and some cereals are fortified with vitamin D, as are many plant-based beverages such as soymilk. Orange juice, yogurt and cheese may or may not be fortified, so it is always good practice to check the Nutrition Facts Label for vitamin D content.

Vitamin D from Supplements

Some people may need extra vitamin D, such as older adults; breastfed infants; people with dark skin; those with certain medical conditions including liver disease, cystic fibrosis, celiac disease and Crohn's disease; and those with obesity or who have had gastric bypass surgery. Always check with your health care provider before taking a vitamin D supplement.

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