Hypovitaminosis D and metabolic syndrome

Metabolic syndrome is a complex disorder characterized by the co-occurrence of several known cardiovascular risk factors, including obesity, insulin resistance, atherogenic dyslipidemia and hypertension. As such, metabolic syndrome is associated with an increased risk of cardiovascular disease and type 2 diabetes mellitus. Of note, metabolic syndrome is defined by the presence of at least three of the following conditions: abdominal obesity (or central obesity), high blood pressure (≥130/≥85 mmHg), abnormal fasting plasma glucose (≥100 mg/dL), elevated serum triglycerides (≥150 mg/dL) and low high-density lipoprotein (HDL)-cholesterol level (<40 mg/dL in men, <50 mg/dL in women). Over the last years, the global prevalence of metabolic syndrome has progressively increased as a consequence of the increasing rates of overweight/obesity, population ageing, and lifestyle changes favoring sedentary behaviors, physical inactivity and unhealthy dietary habits. On the other hand, the global prevalence of vitamin D deficiency has concurrently increased. To date, vitamin D deficiency is regarded as a global pandemic afflicting more than one billion individuals across all age groups worldwide. Since growing evidence suggests that vitamin D exerts several pleiotropic extraskeletal actions beyond its well-established role in the regulation of bone homeostasis, researchers have proposed that vitamin D deficiency may be involved in the pathophysiology of metabolic syndrome. Therefore, this brief Report article aims to summarize the current scientific evidence regarding the possible causal relationship between vitamin D deficiency and metabolic syndrome, as well as the potential favorable effects