VITAMIN D BEYOND THE BONE

Abstract

The discovery of vitamin D receptor (VDR) in many tissues opens a new era in vitamin D (VD) research, far beyond the mineral homeostasis and bone metabolism. The enormous data on the epidemic VD deficiency focused the attention on its role for prevention of numerous diseases, such as cancer, diabetes etc. The calcitriol molecular mode of action ranges from immediate nongenomic responses to long-term genomic effects, linked to cell proliferation, differentiation and survival. In vitro and in vivo studies demonstrate the antiproliferative role of VD. In accordance with this data we have studied prostate cancer patients and determined that VD deficiency was negatively correlated with tumor aggressiveness. The immunomodulatory role of VD has been recognized for many years. Recently, multiple studies have been focused on the role of the VD status on immune response to infection and on the novel effects of VD related to gut microbiota. Studying the effect of VD status in hepatitis C viral infection patients we found VD deficiency correlating with the viral load, liver fibrosis and the effect of antiviral therapy. In an effort to examine the role of VD on gut microbiota, we studied the relation between VD status and the frequency and severity of diarrhea syndrome in toddlers. In all studied children VD deficiency was related to a more severe diarrhea syndrome. By its noncalcitropic effects VD regulates the function of numerous organs and systems including endocrine pancreas, liver, and fat tissue. It is supposed that subclinical VD deficiency may result in insulin resistance, beta-cell dysfunction, diabetes and metabolic syndrome. Our study on normal weight and obese pre-pubertal children revealed VD deficiency in more than 50% of them, correlating with poor metabolic status. In relation to the noncalcemic effects of VD it might be supposed that defining and correcting the VD status of risky groups may reduce the risk of development of socially significant diseases, such as cancer, metabolic and immunodeficient diseases .