Influence of vitamin D in endocrine metabolic diseases

Abstract

The vitamin D deficiency has been linked to the development of several endocrine metabolic diseases such as metabolic syndrome, obesity, hypertension and Type 2 diabetes mellitus. This paper presents an overview of the available scientific evidence for some of the non- calcemic actions of vitamin D in humans, through literature search in scientific databases. The deficiency of vitamin D may predispose to glucose intolerance, changes in insulin secretion and thus the development of type 2 diabetes mellitus. This mechanism is possible due to the presence of the vitamin D receptor in several tissues and cells, including pancreatic ? cells, adipocyte and muscle tissue. In obese individuals, the changes of the vitamin D endocrine system, characterized by high levels of parathyroid hormone and 1,25-dihydroxycholecalciferol are responsible for the negative feedback of hepatic synthesis of 25-hydroxycholecalciferol and also by increased influx of calcium into the intracellular environment, which can damage the secretion and insulin sensitivity. In hypertension, vitamin D could act on the renin-angiotensin system and also in vascular function. There is some evidence that 1,25-dihydroxycholecalciferol inhibits the renin gene expression and blocks the proliferation of vascular smooth muscle cell. Further prospective studies and randomized clinical trials, including studies of supplementation, are required to establish better clinical and metabolic effects of variations in the concentration of 25-hydroxycholecalciferol in the clinical course of these diseases.