Health Topic

Vitamin D

Vitamin D helps your body absorb calcium. You can get Vitamin D in three ways: through your skin, from your diet, and from supplements.

Reviewed Reviewed by a registered pharmacistGeneral information

Also called: Cholecalciferol · Ergocalciferol

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About Vitamin D

Vitamins are substances that your body needs to grow and develop normally. Vitamin D is important to your body because:

  • It helps your body absorb calcium. Calcium is one of the main building blocks of bone. A lack of vitamin D can lead to bone diseases such as osteoporosis or rickets.
  • It also has a role in your nerve, muscle, and immune systems: Your muscles need it to move
  • Your nerves need it to carry messages between your brain and your body
  • Your immune system needs vitamin D to fight off bacteria and viruses

You can get vitamin D in three ways: through your skin, from your diet, and from supplements. Your body forms vitamin D naturally after exposure to sunlight. However, too much sun exposure can lead to skin aging and skin cancer. So many people try to get their vitamin D from other sources.

Very few foods naturally contain vitamin D. Most people get vitamin D in their diet from foods that are fortified. This means that vitamin D is added to the food. These foods may include milk, cereal, and yogurt. Foods that naturally have vitamin D include egg yolks, saltwater fish, and liver.

Vitamin D is available in supplements. It is also included in many multivitamins. The two forms of vitamin D in supplements are D2 and D3. Both types increase vitamin D in your blood, but D3 might raise it higher and for longer than D2. Vitamin D is fat soluble. You can absorb it better when you take your supplements with a meal or snack that includes some fat.

The amount of vitamin D you need each day depends on your age. The recommended amounts, in international units (IU), are:

  • 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
  • If you are pregnant or breastfeeding: 600 IU

But certain people may need extra vitamin D, such as:

  • Older adults
  • Breastfed infants
  • People with dark skin
  • People with certain conditions that limit the absorption of fat, such as Crohn's disease, celiac disease, and ulcerative colitis
  • People who have obesity or have had gastric bypass surgery

Check with your health care provider to see if you need to take vitamin D supplements, and if so, how much you should take. Your provider may want to first do a vitamin D test to see if you are getting enough of it.

It sits within Food and Nutrition.

The lead U.S. institute for this subject is the NIH Office of Dietary Supplements.

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Research on Vitamin D

2,629 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

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Diagnosis and Tests

Related Issues

Statistics and Research

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Vitamin D. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Vitamin D, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.