Excessive doses can result in vomiting, constipation, weakness, and confusion. Other risks include kidney stones. Normal doses are safe in pregnancy. It may not be effective in people with severe kidney disease.
Cholecalciferol is made in the skin following UVB light exposure. It is converted into calcifediol (25-hydroxyvitamin D) by the liver and into calcitriol (1,25-dihydroxyvitamin D) by the kidney. One of its actions is to increase the uptake of calcium by the intestines. It is found in food such as some fish, cheese, and eggs. Certain foods such as milk have cholecalciferol added to them in some countries.
Cholecalciferol was first described in 1936. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. Cholecalciferol is available as a generic medication and over the counter.
Cholecalciferol 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, cholecalciferol 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. Dietary reference intake values for vitamin D (cholecalciferol and/or ergocalciferol) have been established and recommendations vary depending on the country:
Many question whether the current recommended intake is sufficient to meet physiological needs. Individuals without regular sun exposure, the obese, and darker skinned individuals all have lower blood levels and require more supplementation.