MICROANATOMY

Detailed explanation-1: -Vitamin D refers to vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol). Ergocalciferol is produced from irradiated fungi or yeast. Cholecalciferol is produced in skin or found naturally in fatty fish such as salmon or mackerel.

Detailed explanation-2: -Production in Skin Previtamin D3 isomerizes to form vitamin D3 (cholecalciferol), which is subsequently transported into the circulation via a binding protein (11).

Detailed explanation-3: -The epidermis is the major source of vitamin D for the body. Under the influence of sunlight (ultraviolet radiation, action spectrum 280–320nM or UVB) 7-dehydrocholesterol in the epidermis is converted to vitamin D.

Detailed explanation-4: -Vitamin D is the sunshine vitamin that has been produced on this earth for more than 500 million years. During exposure to sunlight 7-dehydrocholesterol in the skin absorbs UV B radiation and is converted to previtamin D3 which in turn isomerizes into vitamin D3.

Detailed explanation-5: -The two major forms are vitamin D2 and vitamin D3. Vitamin D2 (ergocalciferol) is largely human-made and added to foods, whereas vitamin D3 (cholecalciferol) is synthesized in the skin of humans from 7-dehydrocholesterol and is also consumed in the diet via the intake of animal-based foods.