You may know vitamin D as the nutrient that helps keep your bones healthy. But vitamin D actually refers to a group of vitamins. When it comes to your diet and health, the two forms you need to be most concerned about include ergocalciferol, or vitamin D2 and cholecalciferol, or vitamin D3. Your body can use either one of these forms, but their sources vary.
Vitamin D3
Vitamin D is an important vitamin for good health, but is not an essential nutrient because your body can manufacture it on its own. Vitamin D3 is the form of vitamin D manufactured by your body. Through UV radiation, your body converts 7-dehydrocholesterol, found in the top layers of your skin, into vitamin D3. In this form, vitamin D3 is considered a pro-hormone and not really a vitamin because it is not supplied from an outside source.
Vitamin D2
Vitamin D2 is the form of vitamin D found in plants. The plants convert ergosterol through UV radiation into vitamin D2. It differs from vitamin D3 by its chemical structure. However, whether your source of vitamin D is through sun exposure in the form of vitamin D3, or through food in the form of vitamin D2, your body uses it in the same manner. Both forms have been shown to raise your serum 25(OH)D levels, the blood measurement for vitamin D status.
Function
The primary role of vitamin D in your body is to maintain serum calcium and phosphorus levels. It also helps your body absorb calcium, and plays a role in the mineralization of your bones, helping to keep the healthy and strong. Adequate intakes of vitamin D also helps prevent rickets and osteomalacia, causing brittle, thin and misshapen bones. Vitamin D also important for cell growth, nerve function and immune health.
Food Sources
There are very few natural food sources of vitamin D. Fatty fish, such as salmon and mackerel, and fish oil are the best sources and contain vitamin D3. A 3 oz. serving of salmon contains 447 IU of vitamin D. Other food sources of vitamin D3 include egg yolks, cheese and beef liver. Most of the vitamin D in the American diet comes from foods fortified with vitamin D, such as milk, cereal and cheese, in the form of vitamin D3. Mushrooms are your primary source of vitamin D2, mostly found in mushrooms exposed to ultraviolet light in controlled conditions.
Recommended Needs
Your vitamin D needs vary depending on your age. Infants, 0 to 12 months, need 400 IU a day. From age 1 until 70, you need 600 IU of vitamin D a day. All adults over the age of 70 need 800 IU of vitamin D a day.
References
- Office of Dietary Supplements: Vitamin D
- MayoClinic.com; Vitamin D; December 2010
- "Krauses Food, Nutrition and Diet Therapy"; L.Kathleen Mahan, Sylvia Escott-Stump; 1996
Member Comments