Vitamin D: Getting Enough

Topic Overview

Why is it important to get enough vitamin D?

Your body needs vitamin D to absorb calcium. Calcium keeps your bones and muscles, including your heart, healthy and strong.

People who do not get enough vitamin D throughout life have an increased chance of having thin and brittle bones (osteoporosis) in their later years. Thin and brittle bones break easily and can lead to serious injuries. This is why it is important for you to get enough vitamin D as a child and as an adult. It helps keep your bones strong as you get older and protects against possible breaks.

Your body also uses vitamin D to help your muscles absorb calcium and work well. If your muscles don't get enough calcium, then they can cramp, hurt, or feel weak. You may have long-term (chronic) muscle aches and pains. Getting enough vitamin D helps prevent these problems.

Children who don't get enough vitamin D may not grow as much as others their age. They also have a chance of getting a rare disease called rickets, which causes weak bones.

Research suggests that low levels of vitamin D also may be linked to a number of other problems such as high blood pressure, cancer, and heart disease.

What is the recommended daily amount of vitamin D?

Recommendations vary, but experts recently have suggested that people need to get more vitamin D than listed in the dietary reference intakes (DRIs) guideline. The amount of vitamin D you need changes as you get older.

  • Infants starting by age 2 months, children, and teens need 200 to 400 IU a day.1, 2
  • Adults up to age 50 need 400 to 800 IU a day.3, 2
  • Adults age 50 or older need 800 to 1,000 IU a day.3, 2

How can you get enough vitamin D?

You can get enough vitamin D three ways—pills or drops, diet, and sunshine.

Pills or drops. There are different ways you can get vitamin D in pills:

  • You can take a vitamin D pill that you can buy without a prescription.
  • You can also get vitamin D by taking a multivitamin pill. Most multivitamins contain about 400 IU of vitamin D. But don't just take two multivitamins to get 800 IU. Taking more than one pill means that you will also get more of the other vitamins and minerals in the pill, and that can be harmful.
  • Many calcium pills also contain vitamin D, but not enough to meet the recommended daily amount.

You can also take vitamin D drops that you can buy without a prescription. This may be a good choice for infants and for people who don't like to take pills.

Diet. Another way to get vitamin D is from the foods you eat. But most people don't get enough vitamin D through diet alone. That's because there aren't many foods rich in vitamin D. And you would have to eat a lot of them to get 800 to 1,000 IU a day.

Vitamin D is in foods such as4:

  • Eggs. An egg contains about 20 IU of vitamin D. Vitamin D is found in the yolk.
  • Liver. A 3.5 oz (99.2 g) serving of beef liver has about 15 IU of vitamin D.
  • Oily fish like tuna, mackerel, and salmon. A 3 oz (85.1 g) can of tuna packed in oil has about 200 IU of vitamin D. A 3.5 oz (99.2 g) serving of cooked mackerel contains about 345 IU of vitamin D, and a 3.5 oz (99.2 g) serving of cooked salmon contains about 360 IU.
  • Foods with added (fortified) vitamin D, including milk and other dairy products, orange juice, and breakfast cereals. The amount of vitamin D in fortified foods varies. But as a guide, 1 cup of nonfat, reduced fat, or whole milk may contain about 98 IU of vitamin D. A cup of fortified breakfast cereal may contain about 40 IU.

Sunshine. Because your body uses sunshine to make vitamin D, spending time in the sun without sunscreen can help give you the vitamin D you need. People with lighter skin need to let the sun shine on their arms and legs for 10 to 15 minutes a day for a few days a week. People with dark skin would need to spend more time in the sun.

But experts disagree about whether people should spend even 10 to 15 minutes a day in the sun without sunscreen, because sunscreen helps prevent skin cancer. For that reason, you may want to get vitamin D from eating a healthy diet that includes foods fortified with vitamin D and by taking vitamin D pills.

Talk with your doctor about how much and what sources of vitamin D are right for you and your child.

Who may not get enough vitamin D?

Most people don't get enough vitamin D.

Your body uses sunshine to make vitamin D. But in the winter, people often spend more time indoors and don't get enough sun. And using sunscreen, which helps prevents skin cancer, reduces the amount of sun your body gets.

Other things that reduce how much vitamin D your body makes include:

  • Dark skin, such as many African Americans have.
  • Age, especially if you are older than 65.
  • Digestive problems, such as Crohn's or celiac disease.
  • Liver and kidney disease.

Are there any risks from taking vitamin D?

Too much of any vitamin can make a child sick. Be sure to follow your doctor's instructions about using vitamin drops so that you don't give your child too much.

For children and adults, too much vitamin D can cause:

  • Nausea and vomiting.
  • Constipation.
  • Confusion.
  • Heart rhythm problems.
  • Weakness.

Vitamin D may interact with other medicines. A drug interaction happens when a medicine you take changes how another medicine works. One medicine may make another one less effective, or the combination of the medicines may cause a side effect you don't expect. Some drug interactions are dangerous.

Before you start taking vitamin D, tell your doctor about all of the medicines you take, including over-the-counter drugs, herbs, and pills. Also tell your doctor about all of your current medical problems.

References

Citations

  1. Wagner CL, et al. (2008). Prevention of rickets and vitamin D deficiency in infants, children, and adolescents. American Academy of Pediatrics Clinical Report. Pediatrics, 122(5): 1142–1152.
  2. Food and Nutrition Board, Institute of Medicine (2008). Dietary reference intakes (DRIs): Recommended intakes for individuals, vitamins. In LK Mahan, S Escott-Stump, eds., Krause's Food and Nutrition Therapy, 12th ed. St Louis: Saunders Elsevier.
  3. National Osteoporosis Foundation (2008). Prevention. Available online: www.nof.org/prevention/index.htm.
  4. Office of Dietary Supplements, National Institutes of Health (2008). Dietary supplement fact sheet: Vitamin D. Available online: http://www.ods.od.nih.gov/factsheets/vitamind_pf.asp.

Credits

Author Ralph Poore
Editor Patrick Kilby
Associate Editor Michele Cronen
Primary Medical Reviewer Kathleen Romito, MD - Family Medicine
Specialist Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Last Updated April 3, 2009

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