7-dehydrocholesterol

Windaus discovered 7-dehydrocholesterol, which is the chemical precursor of vitamin D, and he showed that it is a steroid. He discovered that it is converted into the vitamin when one of its chemical bonds is broken by the action of sunlight. This explained why exposure to sunlight…

…reaction is the conversion of 7-dehydrocholesterol to vitamin D in the skin. Lack of exposure to solar radiation can cause a deficiency of vitamin D, which leads to a debilitating decalcification of the bones called rickets. This disorder was first described by Roman physicians in the 2nd

…other animals the provitamin (7-dehydrocholesterol), which is found in skin, can be converted by sunlight to vitamin D₃ and thus is an important source of the vitamin. Both vitamin D₂ and vitamin D₃ can be utilized by rats and humans; however, chicks cannot use vitamin D₂ effectively. The form…