Vitamin D is necessary for a healthy body, particularly for strong bones. It also may play a critical role in serious conditions such as cancer and multiple sclerosis, however further research is necessary to confirm its role. While you can obtain vitamin D from sun exposure and food, often there are factors that don't allow you to obtain enough for good health. In these cases, vitamin D supplements are recommended, and they come in two forms -- vitamin D2 and vitamin D3.
Benefits of Vitamin D
Vitamin D plays an important role in bone health. It helps with the absorption of calcium, the mineral most abundant in bone and required for bone strength. A growing body of research points to vitamin D's possible role in many other conditions, including cancer prevention, reducing falls in elderly people and decreasing the risk for multiple sclerosis, among others, notes Medline Plus. Without vitamin D, bones can become soft and brittle causing a painful condition called rickets in children and osteomalacia in adults. An increased risk for osteoporosis, a condition of weak bones more susceptible to fracture, also occurs with a lack of vitamin D.
Sources
Most vitamin D -- about 80 to 90 percent -- is obtained through sun exposure, but many factors may inhibit production including geographical location, skin pigmentation and amount of time spent outdoors. Also, with the use of sunscreen to prevent sun damage and skin cancer, natural vitamin D generation by the skin is limited. For these reasons, vitamin D deficiency is a widespread problem.
Foods also contain vitamin D, but in small amounts that are usually insufficient to meet daily requirements. Salmon, sardines, liver, egg yolk and fortified milk are some vitamin D food sources. When you don't have enough vitamin D in your system, supplements are often recommended.
Vitamin D Supplements
Vitamin D can be formed in a lab. Vitamin D2, called ergocalciferol, comes from lab manipulation of yeast, while vitamin D3, called cholecalciferol, is a byproduct of cholesterol. Both forms are structurally very similar with just one side chain difference. Previous research indicated that D3 was more effective at raising vitamin D blood levels, but both D2 and D3 appear to be equally effective. The Office of Dietary Supplements notes that vitamin D3 may be more potent at high doses, but at nutritional doses D2 and D3 appear equally effective.
Recommendations
Because of debate about vitamin D's growing role in many aspects of good health, some experts called for an increase in recommended daily intake. In 2010 the Institute of Medicine raised daily adequate intake recommendations from 200 to 600 IUs for children and adults under 70. For adults over 70, 800 IUs per day of vitamin D is recommended. The safe upper limit of daily vitamin D intake was also raised from 2,000 IUs per day to 4,000 IUs. Supplements are generally considered safe and are often prescribed by doctors when low levels of vitamin D are detected via blood tests or to treat bone conditions.
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