Vitamin D in adipose tissue and serum 25-hydroxyvitamin D after roux-en-Y gastric bypass

Abstract

Vitamin D is stored in body fat. The purpose of this study was to determine vitamin D concentration in abdominal fat of obese patients who underwent roux-en-Y gastric bypass (RYGB), and to describe changes in serum 25-hydroxyvitamin D (25(OH)D) levels in relation to loss of body fat. Subjects from a single clinic who were scheduled for RYGB were invited into the study. Abdominal subcutaneous, omental, and mesenteric fat were obtained at time of surgery. Adipose vitamin D 2 and vitamin D 3 concentrations were measured by high-performance liquid chromatography (HPLC). Weight and serum 25(OH)D were assessed at baseline and every 3 months up to 1 year. Seventeen subjects were included, and fat samples were available from eleven. Total vitamin D content in subcutaneous abdominal fat was 297.2 727.7ng/g tissue, and a wide range was observed (4-2,470ng/g). Both vitamin D 2 and vitamin D 3 were detected in some of the fat samples. At baseline, 25(OH)D was 23.1 12.6ng/ml. Average weight loss was 54.8kg at 12 months, of which ∼40kg was fat mass. Despite daily vitamin D intake of 2,500 IU throughout the study, no significant increase in serum 25(OH)D was observed, with mean serum concentration of 25(OH)D at 1 year of 26.2 5.36ng/ml (P = 0.58). We conclude that vitamin D in adipose tissue does not significantly contribute to serum 25(OH)D despite dramatic loss of fat mass after RYGB. © 2011 The Obesity Society.