Only a few foods are a good source of vitamin D. These include fortified dairy products and breakfast cereals, fatty fish, beef liver, and egg yolks. Besides increasing sun exposure, the best way to get additional vitamin D is through supplementation. Traditional multivitamins contain about 400 IU of vitamin D, but many multivitamins now contain 800 to 1,000 IU. A variety of options are available for individual vitamin D supplements, including capsules, chewable tablets, liquids, and drops. Cod liver oil is a good source of vitamin D, but in large doses there is a risk of vitamin A toxicity.
The two forms of vitamin D used in supplements are D2 (ergocalciferol) and D3 (cholecalciferol). D3 is the preferred form, as it is chemically similar to the form of vitamin D produced by the body and is more effective than D2 at raising the blood concentration of vitamin D. Since vitamin D is fat soluble, it should be taken with a snack or meal containing fat. In general, 100 IU of vitamin D daily can raise blood concentrations 1 ng/mL after 2 to 3 months (TABLE 2). Once the desired blood concentration is achieved, most people can maintain it with 800 to 1,000 IU of vitamin D daily. Even though dosages up to 10,000 IU daily do not cause toxicity, it generally is not recommended to take more than 2,000 IU daily in supplement form without the advice of a health care provider. Individuals at high risk for deficiency should have a vitamin D blood test first; a dosage of up to 3,000 to 4,000 IU may be required to restore blood concentrations.
US Pharmacist © 2010
Cite this: Vitamin D Supplementation: An Update - Medscape - Oct 01, 2010.