Hypovitaminosis D and adipose tissue – cause and effect relationships in obesity

Abstract

In recent years, attention has been focused on pleiotropic directions of effects exerted by vitamin D. Epidemiological data indicate that deficiency of vitamin D in various population groups represents an increasingly widespread phenomenon, while a decreased serum concentration of calcitriol correlates with manifestation of civilization-linked diseases, including visceral obesity. This study aims at a review and synthesis of data linked to relationships between lowered vitamin D concentrations in blood and manifestation of obesity, and potential mechanisms which affect the concentration of the vitamin in conditions of an excessive accumulation of adipose tissue. Several variables are distinguished which can affect the status of vitamin D in obesity, but the key role in this respect is ascribed to the metabolic activity of visceral adipose tissue. Among others, the activity favours sequestration and modulation of calcitriol turnover. On the other hand, the effects of vitamin D on the process of adipogenesis and its involvement in remodelling of adipose tissue are pointed out. Also, several factors of an environmental nature (e.g. time of year/day, dietetic supply of vitamin D), genetic nature (e.g. genetic polymorphisms) and other conditioning (e.g. coexisting diseases, age, content of melanin in skin) cannot be bypassed as they may affect the concentration of vitamin D. Nevertheless, it still remains unresolved to what extent hypovitaminosis D represents the cause and to which it is the effect of obesity.

Serum Lipid, Vitamin D Levels, and Obesity in Perimenopausal and Postmenopausal Women in Non-Manual Employment

“…Previous studies have shown that obesity may be associated with lower serum vitamin D levels, although the underlying mechanism is not clear [ 17 , 18 ]. One of the possible explanations could be reduced bioavailability of vitamin D due to sequestration in excess adipose tissue [ 1 ].…”

Protective Effects of Fluvastatin on Reproductive Function in Obese Male Rats Induced by High-Fat Diet through Enhanced Signaling of mTOR

“…It is closely related to many diseases such as cardiovascular diseases, insulin resistance, hypertension and endocrine disorders. Furthermore, in recent years, growing evidence suggests that men who are obese due to consumption of HFD have lower quantity and quality sperm, which result in low fertility rate, in comparison with normal weight men [21][22][23]. Weight loss in obese patients can improve or prevent many of the obesity-related risk factors for reduced spermatogenesis and can improve semen quality [24].…”

Correlation of serum 25-hydroxy vitamin D with Leptin and visceral fat area in T2DM patients combined with osteoporosis

“…Vitamin D deficiency is a reliable indicator for OP and increased fracture risk and is an independent risk factor for diabetic osteoporosis [20]. There are indications that the expression of genes such as CYP2J2 and CYP27B1, which encode enzymes responsible for vitamin D synthesis, are reduced in subcutaneous tissues in obese individuals and may, therefore, result in vitamin D deficiency [21]. Over the past few decades, there has been the realization that vitamin D not only affects bone metabolism but also interacts with many other tissues and affects several metabolic pathways including the fat cell metabolism [22].…”