Vitamin D in the light of current knowledge.

Vitamin D, i.e., 1.25(OH)2D, is an essential factor, not only of homeostasis of calcium and phosphorus, but also of cell proliferation, differentiation and apoptosis, immune and hormonal regulation, as well as other body processes.Thus, its optimal presence in the body is of exceptional significance for health, both of children, as well as adults and elderly persons. Today, it is known that the lack of vitamin D, besides having negative effects on the skeleton and teeth, also contributes to the development of various malignancies, primarily of the large bowel, prostate and breasts, as well as of autoimmune and allergic diseases, diabetes mellitus type II, arterial hypertension and others. Considered from the biological aspect, physiological requirements in vitamin D are achieved by cutaneous synthesis from 7-dehydrocholesterol during sun exposure, while, except rarely, it is very scarce in food. Having in mind extensive evidence that sun exposure presents a high risk for the development of skin malignancies, primarily melanoma, it is clear that humans are deprived of the natural and basic source of vitamin D. In accordance, as well as based on numerous epidemiological studies showing the increase of diseases, in the basis of which vitamin D deficiency plays the important role, next led to the recommended dietary allowance of vitamin D, regardless of age. According to current attitudes, it is recommended that the daily dietary allowances of vitamin D, i.e., the quantity of oral intake that would safely cover the optimal body requirements should be 400 IU for ages 0-18 years, 600 IU for ages 19-70 years and 800 IU for persons aged over 70 years.