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Vitamin D: What You Need to Know
Vitamin D: What You Need to Know
What does vitamin D do?

Vitamin D helps your body absorb calcium. Your body needs calcium to build strong bones and teeth in childhood and adolescence. As an adult, you need vitamin D and calcium to maintain bone mass. This helps prevent osteoporosis. Vitamin D also helps your body keep the right amount of calcium and phosphorus in your blood.

Scientists continue to study vitamin D. Recent medical studies have shown that vitamin D may also help protect your body against other conditions, such as cancer, muscle weakness, mood disorders, type 1 and type 2 diabetes, kidney disease, heart disease and high blood pressure.

Does my body create vitamin D?

Vitamin D is sometimes called the "sunshine vitamin" because your body creates vitamin D after you are exposed to sunlight. Depending on where you live, 10 minutes of summer sunshine 3 to 4 times a week may be enough to help your body create the vitamin D it needs.

How much vitamin D do I need?

The amount of vitamin D your body needs can vary depending on your weight, your genetic makeup, your skin color, whether you have any chronic conditions, and even where you live and how much sun exposure you get. Talk to your doctor about how much vitamin D you should be getting in your diet.

Adults need at least the following amounts of vitamin D:

  • 70 years of age and under: 600 international units (IU) daily
  • Over 70 years of age: 800 IU daily

For children from birth to 12 months of age, the recommended daily dose is 400 IU. For children from 1 year of age to 18 years of age, the recommended daily dose is 600 IU. If you breastfeed your baby, your doctor will prescribe a vitamin supplement that has vitamin D (because human milk only has a small amount of vitamin D). Talk to your doctor before giving older children vitamin supplements.

Who is at risk for vitamin D deficiency?
  • Older adults
  • Breastfed infants
  • People who are obese
  • People with darker skin
  • People with limited exposure to sunlight
  • People who live in the northern United States
  • People who have difficulty absorbing dietary fat (because of diseases such as inflammatory bowel disease and cystic fibrosis)
  • People who take medicines called glucocorticoids (one example: prednisone)
What happens if I don't get enough vitamin D?

Many people do not get enough vitamin D. If you don't get enough vitamin D, your body will not be able to absorb calcium well, and your muscles may feel weak.

Children who don't get enough vitamin D are at risk for rickets. Rickets is a disorder that affects the bones, causing them to soften and break easily. Rickets can also cause delayed growth, pain in the bones of the spine, pelvis and legs, and muscle weakness. It can also cause problems with your child's teeth, such as cavities and problems with teeth structure.

Adults who don't get enough vitamin D are at risk for osteomalacia (muscle weakness and weak bones) and osteoporosis (thin bones). New medical studies show that not getting enough vitamin D over a long period of time may also raise a person's risk for other chronic diseases, such as certain kinds of cancer, heart disease and diabetes.

How can I get more vitamin D?

Foods that naturally contain vitamin D include fish, fish oil, eggs, cheese and butter. There are also vitamin-D fortified foods, such as milk and milk alternatives, orange juice and breakfast cereals.

Vitamin D supplements are available over the counter and by prescription. Talk to your doctor if you think that you may not be getting enough vitamin D. He or she will ask you about your diet and your exposure to sunlight, as well as any other risk factors that you may have. Your doctor may also suggest testing your vitamin D level to help you decide if a supplement is needed.

  1. This content was developed with general underwriting support from Nature MadeĀ®.
  2. High Prevalence of Vitamin D Inadequacy and Implications for Health by Holick M(Mayo Clinic Proceedings 03/01/06,
  3. Vitamin D Deficiency by Holick M(New England Journal of Medicine 2007;357:266-281 )
  4. Mayo Foundation for Medical Education and Research. Vitamin D. Accessed 05/12/10
  5. Medline Plus. Vitamin D. Accessed 05/12/10
  6. National Institutes of Health Office of Dietary Supplements. Dietary Supplement Fact Sheet: Vitamin D. Accessed 05/12/10
  7. Vitamin D Council. Understanding Vitamin D Cholecalciferol. Accessed 05/12/10
  8. MedlinePlus. Vitamin D. Accessed 05/12/10