Relationship between vitamin D deficiency and metabolic disorders

Abstract

The relationship between vitamin D deficiency and the metabolic syndrome has recently been revealed. Vitamin D deficiency was hypothesized to cause increased insulin resistance and decreased insulin secretion, which can result in the development of diabetes mellitus and obesity. Cardiovascular diseases are also closely related to the metabolic syndrome. Vitamin D has been shown to have complex multistep metabolism and act as a hormone at many extraskeletal targets. In this literature review, a comprehensive analysis of publications from Scopus, Web of Science, MedLine, The Cochrane Library, EMBASE, Global Health databases, as well as scientific libraries of Ukraine, European Union, Great Britain, USA and other countries was performed. Our goal is to identify and analyze scientific publications discussing various biological effects of vitamin D and its use in the comprehensive treatment of various diseases. In addition to the previously known role of vitamin D in calcium metabolism and the musculoskeletal system functionality, a wide range of its pleiotropic effects has been discovered recently. Modern studies have shown a relationship between low levels of vitamin D and development of neurocognitive dysfunction, mental and neurological disorders, infertility, immune reactivity and autoimmune disorders, various types of cancer, and cardiovascular pathologies. More recent data also revealed a relationship of vitamin D deficiency with practically all aspects of metabolic syndrome, namely diabetes mellitus type 2 and type 1, hyperglycemia, dyslipidemia, obesity, hypertension, and insulin resistance. It was concluded that the data of the modern literature regarding the effectiveness of vitamin D in the treatment and prevention of metabolic disorders and structural and functional changes of the liver in diabetes and non-alcoholic fatty liver disease are quite contradictory: at the same level as the numerous publications on the effective use of vitamin D, there are studies with unconfirmed effectiveness of therapy and even its toxicity for the indicated pathologies.