COMBEL DROPS

Vitamin Dis a group of structurally related,fat-solublecompounds responsible for increasing intestinal absorption ofcalciumandphosphate, along with numerous other biological functions.In humans, the most important compounds within this group are vitamin D3(cholecalciferol) and vitamin D2(ergocalciferol). Unlike the other twelve vitamins, vitamin D is only conditionally essential in the diet, as with adequate skin exposure to theultraviolet B (UVB) radiationcomponent ofsunlightthere issynthesisof cholecalciferol in thedeeper layers of the skin's epidermis. Vitamin D can also be obtained through diet,food fortificationanddietary supplements.For most people, skin synthesis contributes more than dietary sources.In the United States,milkand plant-basedmilk substitutesare fortified with vitamin D3, as are many breakfast cereals. US dietary guides generally assume that all of a person's vitamin D is taken orally, given the potential for insufficient sunlight exposure due to urban living, cultural choices for the amount of clothing worn when outdoors, and use ofsunscreenbecause of concerns aboutsafe sunlight exposure. Cholecalciferol is converted in the liver tocalcifediol(also known as calcidiol or 25-hydroxycholecalciferol), while ergocalciferol is converted to ercalcidiol (25-hydroxyergocalciferol). These two vitamin D metabolites, collectively referred to as 25-hydroxyvitamin D or 25(OH)D, are measured in serum to assess a person's vitamin D status. Calcifediol is further hydroxylated by the kidneys and certain immune cells to formcalcitriol(1,25-dihydroxycholecalciferol; 1,25(OH)2D), the biologically active form of vitamin D.Calcitriol attaches tovitamin D receptors, which arenuclear receptorsfound in various tissues throughout the body. The discovery of the vitamin in 1922 was due to an effort to identify the dietary deficiency in children withrickets.Adolf Windausreceived theNobel Prize in Chemistryin 1928 for his work on the constitution ofsterolsand their connection with vitamins.Present day, government food fortification programs in some countries and recommendations to consume vitamin D supplements are intended to prevent or treat vitamin D deficiency rickets and osteomalacia. There are many other health conditions linked to vitamin D deficiency. However, the evidence for the health benefits of vitamin D supplementation in individuals who are already vitamin D sufficient is unproven.