Vitamin D is known as the sunshine vitamin because most people obtain the majority of their vitamin D from sun exposure. Vitamin D can also be found in dietary sources such as dairy products, fish and fortified breakfast cereals and is available in supplement form. It is known to aid in bone health, according to the Mayo Clinic, and is currently being researched for its uses in many other areas of health such as diabetes, cancer and heart disease.
Types of Vitamin D
Vitamin D is found in two forms: vitamin D2, also known as erogcalciferol, and vitamin D3, also known as cholecalciferol. Vitamin D2 is formed by plants and vitamin D3 is formed in humans through exposure to ultraviolet-B (UVB) rays from the sun. Vitamin D fortified foods may be fortified with either vitamin D2 or D3.
Vitamin D2
Vitamin D2 is not the naturally occurring form of the vitamin in the human body. Vitamin D2 can be found in supplemental forms, and your doctor may prescribe a high-dose of vitamin D2 if you are found to be deficient. The prescription dose of 50,000 International Units (IU) weekly may seem high but is considered safe because Vitamin D2 is about half as strong as vitamin D3.
Vitamin D3
When people say vitamin D, they are typically talking about vitamin D3. This is the naturally occurring form of vitamin D in the body and is found in most over-the-counter supplements. Vitamin D3 is produced through exposure to UVB radiation, and exposure to the sun for 20 to 30 minutes can produce 10,000 IU of vitamin D in light-skinned people, according to the Vitamin D Council. You don't have to worry about toxicity from sunlight, because the body is very good at preventing the use of any excess vitamin D that is created.
Vitamin D Deficiency
Vitamin D deficiency has become a major concern. It is estimated that a billion people worldwide have either an insufficiency or a deficiency of vitamin D. Deficiency is diagnosed through a serum blood sample. A serum level of less than 30 nanograms per milliliter (ng/ml) is considered an insufficiency, while a level of less than 20 ng/ml is considered to be a deficiency. If you have very little intake of vitamin D in your diet or you live in a northern part of the world with limited sunlight for part of the year, you may find it difficult to maintain adequate levels of the vitamin.
Current Vitamin D Recommendations
Because vitamin D has not only been linked to bone health but could also potentially affect other health conditions, you may benefit from supplementation with vitamin D if you do not get enough in your diet. The Institute of Medicine recommends an adequate intake of 200 IU of vitamin D daily for children and adults up to 50 years of age. For adults 51 to 70 years of age an adequate intake of 400 IU is recommended, and for those 71 years and older, 600 IU is recommended. Many experts believe that the current recommendations are too low, and intakes of between 800 to 1000 IU per day in children and adults may be necessary, especially for those with limited sun exposure. The Vitamin D Council recommends 5000 IU per day for those who avoid the sun.
If you plan to start a new supplement of any kind, be sure to first talk with your doctor to determine if it is appropriate for you.
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