**4. Conclusions**

The prevalence of obesity and VDD is growing exponentially in recent decades, and several studies have been conducted worldwide, particularly, the signs of VDR and hydroxylase enzymes in AT (SAT and VAT). VD is a nutrient with important role in the genesis of obesity and also in diseases associated with chronic inflammation. It features an anti-inflammatory effect in AT, anti-adipogenic activity, exerts immunoregulatory effect, and has the capacity to limit the expression of inflammatory markers in AT. Scientific evidences suggest that AT is a target for VD action, as CYP27B1 and VDR genes that are expressed by adipocytes. All evidence suggests that 25(OH)D, 1,25(OH)2D, and VDR are involved in the AT, through the endocrine system as well as autocrine/paracrine actions of VD.

Based on news researches, there is a hypothesis that AT is not only a stock of VD but also has a dynamic ability to activation and deactivation of this vitamin in obesity. Low VD status in obesity may have implications for AT biology based on recent data from different research groups which are converging to highlight the impacts of VD on AT/adipocyte biology. Therefore, some key points have yet to be elucidated in relation to VD metabolism and its regulation on AT, especially in obese environment.
