<unk>  appears to stimulate the body's interferon type I signaling system that protects against bacteria and viruses, unlike vitamin D2. Vitamin D deficiency<unk>  is a form of vitamin D which is naturally synthesized in skin and functions as a pro-hormone, being converted to calcitriol. This is important for maintaining calcium levels and promoting bone health and development. As a medication,<unk>  may be taken as a dietary supplement to prevent or to treat vitamin D deficiency. One gram is 40,000,000 (40x106) IU, equivalently 1 IU is 0.025 µg or 25 ng. Dietary reference intake values for vitamin D<unk>  and/or ergocalciferol) have been established and recommendations vary depending on the country: *In the US: 15 µg/d (600 IU per day) for all individuals (males, females, pregnant/lactating women) between the ages of 1 and 70 years old, inclusive. For all individuals older than 70 years, 20 µg/d (800 IU per day) is recommended. *In the EU (except France): 20 µg/d (800 IU per day) *In France: 25 µg/d (1000 IU per day) Low levels of vitamin D are more commonly found in individuals living in northern latitudes, or with other reasons for a lack of regular sun exposure, including being housebound, frail, elderly, obese, having darker skin, or wearing clothes that cover most of the skin. Supplements are recommended for these groups of people. The Institute of Medicine in 2010 recommended a maximum uptake of vitamin D of 4,000 IU/day, finding that the dose for lowest observed adverse effect level is 40,000 IU daily for at least 12 weeks, and that there was a single case of toxicity above 10,000 IU after more than 7 years of daily intake; this case of toxicity occurred in circumstances that have led other researchers to dispute it as a credible case to consider when making vitamin D intake recommendations. Patients with severe vitamin D deficiency will require treatment with a loading dose; its magnitude can be calculated based on the actual serum 25-hydroxy-vitamin D level and body weight. There are conflicting reports concerning the relative effectiveness of<unk>  <unk>  versus ergocalciferol (D2), with some studies suggesting less efficacy of D2, and others showing no difference. There are differences in absorption, binding and inactivation of the two forms, with evidence usually favoring<unk>  in raising levels in blood, although more research is needed. A much less common use of<unk>  therapy in rickets utilizes a single large dose and has been called stoss therapy. Treatment is given either orally or by intramuscular injection of 300,000 IU (7,500 µg) to 500,000 IU (12,500 µg = 12.5 mg), in a single dose, or sometimes in two to four divided doses. There are concerns about the safety of such large doses. Other diseases A meta-analysis of 2007 concluded that daily intake of 1000 to 2000 IU per day of vitamin<unk>  could reduce the incidence of colorectal cancer with minimal risk. Also a 2008 study published in Cancer Research has shown the addition of vitamin<unk>  (along with calcium) to the diet of some mice fed a regimen similar in nutritional content to a new Western diet with 1000 IU<unk>  per day prevented colon cancer development. In humans, with 400 IU daily, there was no effect of<unk>  supplements on the risk of colorectal cancer. Supplements are not recommended for prevention of cancer as any effects of<unk>  are very small. Although correlations exist between low levels of blood serum<unk>  and higher rates of various cancers, multiple sclerosis, tuberculosis, heart disease, and diabetes, the consensus is that supplementing levels is not beneficial. It is thought that tuberculosis may result in lower levels. It, however, is not entirely clear how the two are related.
Cholecalciferol
Ergocalciferol
Calcitriol
Calcium/cholecalciferol
Folate
Tocopherol
Calamine
Retinol