Vitamin D Storage in Adipose Tissue of Obese and Normal Weight Women

ABSTRACT Although vitamin D deficiency is prevalent among obese individuals, its cause is poorly understood. Few studies have measured vitamin D concentrations in adipose of obese (OB) subjects, and none have included normal weight controls (C). The goal of this study was to investigate whether the relationship between body composition, serum 25‐hydroxyvitamin D (25OHD), vitamin D in subcutaneous (SQ) and omental (OM) adipose, and total adipose stores of vitamin D differ among OB and C. Obese women undergoing bariatric surgery and normal‐weight women undergoing abdominal surgery for benign gynecologic conditions were enrolled. Subjects had measurements of serum 25OHD by high‐performance liquid chromatography (HPLC) and body composition by dual‐energy X‐ray absorptiometry (DXA). Vitamin D concentrations in SQ and OM adipose were measured by mass spectroscopy. Thirty‐six women were enrolled. Serum 25OHD was similar between groups (OB 27 ± 2 versus C 26 ± 2 ng/mL; p = 0.71). Adipose vitamin D concentrations were not significantly different in either SQ (OB 34 ± 9 versus C 26 ± 12 ng/g; p = 0.63) or OM compartments (OB 51 ± 13 versus C 30 ± 18 ng/g; p = 0.37). The distribution of vitamin D between SQ and OM compartments was similar between groups. Serum 25OHD was directly related to adipose vitamin D in both groups. Total body vitamin D stores were significantly greater in OB than in C (2.3 ± 0.6 versus 0.4 ± 0.8 mg, respectively; p