Vitamin D is a group of fat-soluble pro-hormones consisting of 5 different vitamins: Vitamin D1, D2, D3, D4 and D5. The two most important forms in which vitamin D can be found are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol), both of which have very similar biological activity.
Ergocalciferol (D2) is of vegetable origin, while cholecalciferol (D3), deriving from cholesterol, is synthesized in animal organisms. The main source of vitamin D for the human body is exposure to solar radiation. Vitamin D obtained from sun exposure or through diet is present in a biologically inactive form and must undergo two hydroxylation reactions to be transformed into calcitriol, the biologically active form.
The study: Vitamin D, the natural way, published on the Clinical nutrition ESPEN, explains the importance of vitamin D above all as a natural element. We can read the abstract: "Vitamin D is a fat-soluble vitamin whose main function in the body is the regulation of bone mineral metabolism.
In the last two decades, there has been an intensive research for possible vitamin D benefits in non-skeletal health but as today it still remains unclear. The aim of this article is to review vitamin D metabolism and the natural sources to encourage lifestyle changes to avoid deficiency.
Universal screening for vitamin D deficiency is not warranted and it should only be done in cases with risk factors for vitamin deficiency. Vitamin D is measured in the body by determining 25-hydroxycholecalciferol; values below 20 ng / mL (50 nmol / L) are considered inadequate.
The three sources of vitamin D are the ultraviolet sun radiation, diet and supplementation. The role of vitamin D supplementation out of the osteoporosis treatment and prevention still remain controversial. Healthy sun exposure and diet should be discussed with all patients with vitamin D deficiency and in general population in promoting health.
The skin, through solar radiation, is the main source of vitamin D and provides 90% of the body's needs. Changing lifestyle habits, encouraging a controlled sun exposure and proper vitamin D diet is a preventive strategy that should be applied in our daily practice to prevent osteoporosis and other diseases associated with low vitamin D."