Vitamin D is a nutrient needed for health and to maintain strong bones. It helps the body absorb calcium (one of bone’s main building blocks) from food and supplements. It is found in fatty fish such as salmon and tuna, fortified breakfast cereals, fortified milk, beef liver, eggs, cheese, and mushrooms,among other foods. The body makes vitamin D when skin is directly exposed to the sun, and most people meet at least some of their Vitamin D needs this way. It is also available in supplements.
Muscles need vitamin D to move, nerves need it to carry messages between the brain and every body part, and the immune system needs it to fight off invading bacteria and viruses. Together with calcium, vitamin D also helps protect older adults from osteoporosis.
The amount you need each day depends on your age. Average daily recommended amounts from the Food and Nutrition Board for different ages are listed below in International Units (IU):
Birth to 12 months: 400 IU
Children 1–13 years: 600 IU
Teens 14–18 years: 600 IU
Adults 19–70 years: 600 IU
Adults 71 years and older: 800 IU
Pregnant and breastfeeding women: 600 IU
Source: National Institutes of Health Office of Dietary Supplements