Vitamin D - an important part of nutrition

Vitamin D is also called as Calciferol.  There are two types of vitamin D known as vitamin D₂ (ergocalciferol) and vitamin D₃ (cholecalciferol) in animal body. The body can synthesize it from cholesterol when the sun exposer is adequate. Hence the nickname for vitamin D is “sunshine vitamin”.  Vitamin D enables the body to absorb calcium and phosphorous from food materials. Most of the body’s vitamin D is made in the skin by the action of sunlight. So in prolonged dull weather extra supplies are required. In the liver vitamin D is converted in to calcidiol. Part of the calcidiol is converted in to calcitriol by the two kidneys. Calcidiol is also converted in to calcitriol outside of the kidney for other

purposes like proliferation, differentiation and apoptosis of cells .calcitriol affects neuromuscular function and inflammation too. The calcitriol is the biologically active form of vitamin D. And also this is a hormone which circulates in the blood to regulate the concentration of calcium and phosphate in the bloodstream. It also promotes the healthy growth and remodeling of bones. Vitamin A is stored in the liver.

Most of the natural foods are low in vitamin D, except oily fishes like mackerels, sardines and herring, fish liver oils and egg yolk. Nowadays vitamin D supplement is added to some foods such as margarine (to which it must be added by law) and some breakfast cereals.