Uses of Vitamin D2

Sometimes called the "sunshine vitamin" because the skin can produce it through contact with the ultraviolet rays of the sun, vitamin D performs several significant bodily functions, including assisting calcium absorption. Very few food sources provide this fat-soluble vitamin, and deficiencies often occur among the elderly, strict vegetarians, people living in northern climates and those who limit sun exposure. Supplementation is common, with two distinct forms available: ergocalciferol, or vitamin D2, and cholecalciferol, or vitamin D3. Research on their differences has been mixed.

Difference Between Vitamin D2 and Vitamin D3

Vitamin D2 is plant-derived and is the form of this vitamin contained most often in prescriptions, supplements and fortified foods. Some research suggests that vitamin D2 is not the best form of this vitamin available and may contain less than one-third the potency of vitamin D3; for this reason, some multivitamin manufacturers have switched to D3. However, a study in the "Journal of Endocrinology and Metabolism" in 2008 found no difference in the effects of supplementation with 1,000 IU of vitamin D2 and the same amount of vitamin D3. To prevent deficiency, the recommended daily allowance of vitamin D for ages 1 to 70 is 600 IU. Ask your doctor or nutritionist which form of vitamin D is best for you.

Sources of Vitamin D

The best source of vitamin D appears to be direct contact with sunlight. According to Dr. Michael F. Holick, writing in the journal "Mayo Clinic Proceedings" in 2003, exposure to sunlight for 5 to 15 minutes from 11 a.m. to 2 p.m. a few times a week is sufficient for making adequate vitamin D. Dark-skinned people will have a difficult time absorbing enough of this vitamin from the sun, however, and those with skin cancer need alternate sources. Mushrooms supply vitamin D2, while foods with vitamin D3 include canned salmon, tuna and sardines and cod liver oil.

Bone Support

The best-known use of vitamin D is helping the body absorb calcium, and the type most frequently linked to this function is D2. In the 1930s, researchers discovered that fortification of milk with vitamin D2 successfully prevented rickets, a softening of the bones in children. Vitamin D works in conjunction with both calcium and magnesium to build bone, and also helps decrease the loss of calcium through the urinary tract. Deficiency of vitamin D may also manifest in adults as osteoporosis, a decrease in bone density that may lead to fracture, or osteomalacia, a weakening of the bones that may result in deformity.

Anti-Cancer

Vitamin D may have benefits for several types of cancer, particularly colorectal, breast and prostate. Test-tube studies show that vitamin D may suppress cancer cell growth, and human studies have also been promising for these cancers, according to the Linus Pauling Institute. For example, one five-year study of 120,000 men found that high vitamin D intake reduced colorectal cancer risk by 29 percent. Likewise, a study that followed 88,000 women for 16 years found a link between high vitamin D intake and reduced breast cancer risk. In this study, the authors recommended intake of 2,000 IU daily plus mild sun exposure to reap the anti-cancer benefits.

Other Uses

Vitamin D may also treat medical conditions such as insulin-dependent, or type 1, diabetes, rheumatoid arthritis and multiple sclerosis. A 30-year study in Finland of subjects born in 1966 and given a vitamin D supplement during their first year of life found they had a significantly lower risk of developing type 1 diabetes. In other uses of vitamin D, a meta-analysis performed in 2007 at the International Agency for Research on Cancer linked intake of this vitamin with a general decrease in mortality rates due to any causes. However, a reanalysis of the findings in 2010 concluded that research was "inconsistent."