Role of vitamin D in obesity

Hypovitaminosis D and obesity represent global public health problems. Plasma concentrations of 25 (OH) D\r\nare more strongly correlated with visceral adipose tissue than subcutaneous fat, suggesting a link between\r\nvitamin D levels, insulin resistance and cardiometabolic risk, particularly in younger subjects. Various studies\r\nhave shown that obesity is an important risk factor for vitamin D deficiency and how adiposity has a\r\ndetermining role in the serum level of vitamin D. The association between these two factors is complex and the\r\nmultiple studies carried out to clarify this association have not provided univocal indications. Some hypotheses\r\npropose that the deficiency of vitamin D may remain a cause of obesity. However, the possible\r\npathophysiological mechanisms do not exclude a multifactorial origin, thus supporting the importance of\r\nsupplementing vitamin D in obese patients. Since adipose tissue is a major reserve of vitamin D, its role in the\r\nregulation of adipogenesis, insulin sensitivity, and in the reduction of cytokine release and adipose tissue\r\ninflammation has been demonstrated. Moreover, studies on the vascular effect of vitamin D have been carried\r\nout. This review attempts to summarize the current understanding regarding the causes of the reduced vitamin D\r\nlevels in obese patients, the effects of vitamin D supplementation in these individuals, and the prevention of the\r\ncomplications associated to obesity such as the chronic inflammatory state and vascular complications which\r\npredispose to cardiovascular risk.