What is vitamin D and why is it important?
Vitamin D is an essential nutrient that is an important part of your overall good health. Your body requires vitamin D to absorb calcium and phosphorus. Calcium and phosphorus are essential in building and maintaining strong bones and teeth.
Maintaining an adequate level of vitamin D is important for all stages of life. It helps to promote bone formation in children and can slow or stabilize bone loss in older adults. The benefits of vitamin D reach far beyond bone health. Sufficient levels of vitamin D in the body may protect against various health conditions, such as some cancers, muscle weakness, mood disorders, diabetes, kidney disease, heart disease, and high blood pressure.
What happens if I do not get enough vitamin D?
A low level of vitamin D in the body is referred to as a “vitamin D deficiency.” When the body is low in vitamin D, calcium and phosphorus cannot be absorbed, which can cause serious health problems. Long-term vitamin D deficiency may also raise a person’s risk for other chronic diseases, such as certain kinds of cancer, heart disease, and diabetes.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 do not get enough vitamin D are also at risk for osteomalacia (weak bones), osteoporosis (thin bones), and muscle weakness. This can increase the risk of bone fractures and falls.
How do I get vitamin D?
There are 3 ways to get vitamin D: exposure to sunlight, vitamin D-fortified foods, and dietary supplements.
Vitamin D is sometimes called the “sunshine vitamin” because your body can create its own vitamin D when you are exposed to sunlight. Depending on where you live, you might only need 10 minutes of summer sunshine 3 to 4 times a week to help your body create the vitamin D it needs. This can happen while you’re taking your dog for a run or your children to the local park to play. On the other hand, at some times of the year, especially in northern states, there may not be enough of the right sunlight to make vitamin D, even if you are outside all day.
Vitamin D-fortified foods:
Most people get very little vitamin D from the foods they eat, because there are very few foods that contain vitamin D. Foods that naturally contain vitamin D include fatty fish, fish oil, eggs, cheese, and butter. There are also foods and drinks that have been fortified with vitamin D, such as milk, milk alternatives, some brands of orange juice, and some vitamin-fortified breakfast cereals. Read the food nutrition labels to learn if the products you choose are sources of vitamin D.
Vitamin D is available both over the counter and by prescription. If you are concerned that you are not getting enough vitamin D, be sure to talk to your family doctor. 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 family doctor may also suggest testing your level of vitamin D; this will help you decide if a supplement is needed and how much you should take.
If you are a senior, a vegetarian or vegan, a nursing mother, or a pregnant woman, talk to your family doctor about whether you should take a vitamin D supplement.
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.Adults need at least the following amounts of vitamin D:
- 70 years of age and younger: 600 international units (IU) daily
- Older than 70 years of age: 800 IU daily
For children from 1 year of age to 18 years of age, the recommended daily dose is 600 IU. For children from birth to 12 months of age, the recommended daily dose is 400 IU. If you breastfeed your baby, your family doctor will prescribe a vitamin supplement that has vitamin D for him or her (because breast milk only has a small amount of vitamin D). Talk to your family doctor before giving older children vitamin supplements.
Am I at risk for vitamin D deficiency?
People who are at risk for vitamin D deficiency include:
- Infants who are only breastfed
- Babies and toddlers who are given non-milk food products or foods that are not fortified with vitamin D
- Seniors or older adults
- People who have darker skin
- People who get limited exposure to sunlight, including people who are homebound
- People who have difficulty absorbing dietary fat (because of conditions such as colitis, inflammatory bowel disease, and cystic fibrosis)
- People with dietary restrictions, such as vegan, milk-allergic, ovo-vegetarian, and lactose-intolerance
- People who are obese (body mass index [BMI] ≥30)
- People with kidney disease, including kidney transplant recipients
- People who take medicines called glucocorticoids (one example: prednisone)
- People who live in the northern states, especially during the winter months (in other words, the farther south you live, the easier it is to get your vitamin D from sun exposure all year round)
- High Prevalence of Vitamin D Inadequacy and Implications for Health by Holick M (Mayo Clinic Proceedings March 01, 2006)
- Vitamin D Deficiency by Holick M (New England Journal of Medicine 2007;357:266-281 )
- Mayo Foundation for Medical Education and Research. Vitamin D. Accessed May 12, 2010
- Medline Plus. Vitamin D. Accessed May 12, 2010
- National Institutes of Health Office of Dietary Supplements. Dietary Supplement Fact Sheet: Vitamin D. Accessed May 12, 2010
- Vitamin D Council. Understanding Vitamin D Cholecalciferol. Accessed May 12, 2010
- MedlinePlus. Vitamin D. Accessed May 12, 2010
Copyright © American Academy of Family Physicians
This information provides a general overview and may not apply to everyone. Talk to your family doctor to find out if this information applies to you and to get more information on this subject.