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.