Vitam D 3 and metabolic syndrome

Metabolic syndrome is defined as a simultaneous coexistence of four cardiovascular risk factors – hypertension, insulin resistance, obesity, and atherogenic dyslipidemia (Huang, 2009). It represents one of the greatest burdens of modern society, giving the estimations that there is an increasing incidence of metabolic syndrome, not just in adults, but also in children (Harrell, Jessup, & Greene, 2006). Current prevalence of metabolic syndrome is over 20% in the population aged 20 years and older, and over 40% in population older than 40 (Kereiakes & Willerson, 2003). The definition and criteria for diagnosing metabolic syndrome was changed several times the past few decades. In 1988, Raven named it “syndrome X”, and defined it as a group of metabolic disorders including hypertension, insulin resistance, and various types of lipid abnormalities. In 1999, World Health Organization (WHO) came up with a new definition which characterized metabolic syndrome as insulin resistance combined with two or more of following risk factors: Hypertension, increased plasma triglyceride level and/or low HDL cholesterol, central obesity, and microalbuminuria. This definition has been amended by European Group for Study of Insulin Resistance, National Centers for Environmental Prediction (NCEP), American Association of Clinical Endocrinologists, and many others, so now we have several different criteria to diagnose metabolic syndrome (Parikh & Mohan, 2012). There are many possible factors influencing the increasing trend of metabolic syndrome, including changed lifestyle, disturbed nutritional and increased caloric value of the food, stress, etc. Besides macronutrients, it has been shown that the occurrence of metabolic syndrome, especially the obesity component, is associated with the lack of some important micronutrients in food (Garcia, Long, & Rosado, 2009). One of the micronutrients that received the greatest attention is vitamin D3, due to its possible strong connection with metabolic syndrome, especially with insulin resistance component (Martini & Wood, 2006). Vitamin D is a fat-soluble vitamin also known as calciferol. There are two most important forms of calciferol – vitamin D2 (ergocalciferol), and vitamin D3 – (cholecalciferol). Vitamin D3 is the only known vitamin that can be synthesized in human organism. Its production is accomplished through the series of metabolic pathways taking place in skin, liver, and kidneys. The other way of obtaining calciferol is by ingestion of food or dietary products rich in this vitamin. Positive effects of vitamin D have been scientifically confirmed in persons with various disorders. There are data suggesting that it reduces tumor growth, modifies the course autoimmune diseases, strengthens the immune system, improves the symptoms of neurological disorders, and improves heart muscle function. The importance of vitamin D in adequate development and dynamic properties of bone tissue physiology is well established (Bergink et al., 2009). This paper is aimed to provide a review of currently available scientific literature dealing with relationship between vitamin D deficiency and metabolic syndrome, and to try to investigate the existence and nature of this relationship in selected group of individuals.