Overview

Vitamin D is a nutrient the body needs, along with calcium, to build bones and keep them healthy. The body can absorb calcium only if it has enough vitamin D. Calcium is a major part of bones.

Vitamin D also has many other uses in the body. It supports immune health and helps keep muscles and brain cells working.

Vitamin D isn't in many foods unless it's added. It's added to fortified milk and cereal. And it's in fish such as salmon, mackerel, and sardines. The body also makes vitamin D from direct sunlight on the skin.

How much vitamin D the body makes depends on many things. These include the time of day you're in the sun, what season it is, where you live, and the color of your skin. Depending on where you live and your lifestyle, you might get little to no vitamin D from the sun during winter. Although you need sunscreen to prevent skin cancer, using it also can lessen how much vitamin D your body makes.

Many older adults don't get enough direct sunlight. They also may have trouble taking in vitamin D. Other people who may not get enough vitamin D are breastfed babies, people with Black or brown skin, and people who have obesity or have had gastric bypass surgery. People with conditions that affect how the body absorbs fat, such as ulcerative colitis and Crohn's disease, also may not get enough vitamin D.

If you think you don't get enough vitamin D, talk with your healthcare professional. A simple blood test can check the levels of this vitamin in your blood.

Taking a vitamin D supplement or a multivitamin with vitamin D may help improve bone health. The recommended daily amount of vitamin D is 400 international units (IU) for children up to age 12 months, 600 IU for people ages 1 to 70 years, and 800 IU for people over 70 years.