Although known since 1922, vitamin D3 or cholecalciferol was identified only as recently as the late 1960s as the precursor of the active steroid 1,25-dihydroxyvitamin D3 or calcitriol, and this active steroid was known for its involvement in the metabolism of calcium—i.e., for its effects on bone mineralization. For this reason, children were administered fish oils, which are highly concentrated in vitamin D3. Food supplementation with vitamin D is common today and benefits the entire population.
Initially, the metabolism of vitamin D3 to calcitriol was thought to occur only in the liver and kidneys. However, the vitamin D receptor (VDR) for 1,25-dihydroxyvitamin D3 was more recently discovered in more than 30 tissues or organs including the skin, thus initiating new studies and reports on the activities of vitamin D metabolites and their regulation of important cellular skin functions.
