Background: The degree of bariatric surgery (BS) induced vitamin D (VD) malabsorption is not well established.
Objective: The aim of this study is to evaluate the efficacy and safety of achieving 25-hydroxy VD (25(OH)D) levels ≥75 nmol/L with two regimens of VD supplementation after BS.
Methods: We performed two open-label, prospective studies in patients undergoing BS from 2009 to 2011. Postoperatively, all patients received Ca citrate 1,000 mg and 800 IU of VD3/day. In the first study, additional VD3 was prescribed according to preoperative 25(OH)D levels- < 25 nmol/L:2,800 IU/day; 26-50 nmol/L:2,000-1,200 IU/day, 51-62 nmol/L:1,000 IU; >63 nmol/L:0 IU/day-and we evaluated the patients at baseline and at 4 months. In the second study, an additional fixed high dose of 2,000 IU/day of VD3 was administered, and we evaluated patients at baseline and at 4 and 12 months after BS.
Results: The first study included 176 patients [mean age 44 (11)]; 140 were females. Before BS, 171 subjects (98 %) presented 25(OH)D levels <75 nmol/L. Postoperatively, the mean 25(OH)D levels increased from 40 (17) to 77 nmol/L (29) (p < 0.001) with no differences in parathormone (PTH) or 25(OH)D levels between dose groups. In the second study, we enrolled 52 patients [mean age 45 (10)]; 32 were females. Postoperatively, the mean 25(OH)D levels increased from 32 (12) to 80 (22) and to 75 nmol/L (15) (p < 0.001) at 4 and 12 months, respectively. In both studies, a high percentage of patients achieved 25(OH)D ≥75 nmol/L levels and no subject reported any serious adverse event.
Conclusions: Both schedules of daily VD3 supplementation were effective and safe under conditions of clinical practice.