Vitamin D Supplementation Efficacy: Sleeve Gastrectomy Versus Gastric Bypass Surgery

Background: Vitamin D deficiency is common with bariatric surgery, and few prospective studies comparing different surgical procedures have evaluated appropriate vitamin D supplementation levels. Therefore, vitamin D₃ and calcium supplementation were evaluated following gastric bypass and sleeve gastrectomy. Methods: Women consumed 2,000 international units (IU) of vitamin D₃ and 1,500 mg calcium citrate daily for 3 months following gastric bypass (n = 11) and sleeve gastrectomy (n = 12). Height, weight, body mass index (BMI), serum 25-hydroxyvitamin D [25(OH)D], and serum PTH concentrations were measured preoperatively and at 3 months. Wilcoxon signed rank analyses compared body weight parameters, serum 25(OH)D and PTH concentrations, and dietary intakes of vitamin D and calcium preoperatively and at 3 months. Vitamin D deficiency was defined as a serum 25(OH)D concentration <20 ng/mL (50 nmol/L). Results: Vitamin D deficiency decreased from 60.6 % preoperatively to 26.1 % after 3 months (P < 0.005). Serum 25(OH)D concentrations increased an average of 8 ng/mL (P < 0.001), and PTH concentrations decreased an average of 9 ng/L, although reductions were not significant. Overall, the response to supplementation following gastric bypass and sleeve gastrectomy did not differ. Conclusions: Reduced food intake increased the risk of vitamin D deficiency following bariatric surgery. However, daily supplementation with 2,000 IU of vitamin D₃ and 1,500 mg calcium citrate significantly increased 25(OH)D concentrations and reduced the percent of women who were vitamin D deficient. Although serum 25(OH)D concentrations did not reach levels associated with detrimental health effects, several women remained vitamin D deficient and more aggressive supplementation may be indicated.