Low levels of vitamin D3 are linked to several health conditions, including a higher risk of osteoporosis, diabetes and breast cancer. Understanding the function of vitamin D in the body and correct vitamin D3 levels can help you, with the guidance of your physician, make choices about vitamin D supplementation.
Vitamin D
Vitamin D helps maintain appropriate blood levels of calcium and phosphorus, aiding in the absorption of calcium. Vitamin D exists as two types, ergocalciferol, or vitamin D2, and cholecalciferol, or vitamin D3. Vitamin D3 is the type synthesized by humans. Foods can be supplemented with either type of vitamin D. The liver converts both types of vitamin D into calcidiol in the body.
Considerations
Some individuals are at especially high risk of vitamin D deficiencies, including the elderly, those with limited sun exposure and individuals with certain disorders, including Crohn's disease and cystic fibrosis. Individuals with darker skin tones and the obese might also be at higher risk of deficiencies. Limited sun exposure might be the result of lifestyle, or simply living in a Northern climate that receives less sunlight.
Testing
If you're concerned about your vitamin D levels, ask your health care provider for a 25-hydroxyvitamin D test, a simple blood test to measure the level of calcidiol in the bloodstream. Levels from 20 to 50 ng/mL are considered normal, but consult your physician about the correct vitamin D level for you. If your levels are low, your doctor might recommend a vitamin D supplement.
Foods and Supplementation
While the body can produce vitamin D through sunlight absorption, some foods contain vitamin D. Milk and cereals contain supplemental vitamin D, while fatty fish are a naturally occurring source of the essential vitamin. If your physician has indicated it is necessary, or you are at high risk for vitamin D deficiency, you might wish to add an additional vitamin D supplement. The U.S. Food and Drug Administration recommends 600 to 800 international units, or IU, of vitamin D daily, depending on age. Avoid supplementing with more than 2,000 IU of vitamin D without your physician's supervision, recommends Dr. Edward Giovannucci at the Harvard School of Public Health.
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