Severe obesity and vitamin D deficiency treatment options before bariatric surgery: a randomized clinical trial.

Background: Obesity, which has various complications and co-morbidities, is an epidemic issue worldwide. Vitamin D deficiency (VDD) is a well-known metabolic disorder among patients with severe obesity. While they are good candidates for bariatric surgery, this deficiency can affect the outcome of surgery negatively.

Objectives: The aim of this study was to compare 3 different VDD treatment strategies for use before bariatric surgery and compare serum vitamin D levels after 7 weeks.

Settings: University hospital, Isfahan, Iran.

Methods: This was a single-blinded, randomized clinical trial on 100 patients who were referred for bariatric surgery from 2016 to 2018. Vitamin D (VitD) level was checked before surgery for the patients included in the study, if their VitD level was <30 ng/mL. We rechecked their serum VitD in the 8 week, after 7 weeks of treatment. The participants were randomly allocated into 3 groups: 33 patients were treated with 50,000 units VitD capsules every week for 7 weeks; 33 patients were treated with a single dose of 300,000 units VitD ampoule; and 34 patients were treated with a combination of a half of the injection dose, followed by the oral capsule for 4 weeks.

Results: No case was lost during the follow-up time. No significant differences were found among the 3 groups in terms of their age (P = .654), body mass index (P = .434), sex (P = .799), initial 25(OH) VitD level (P = .273), and history of supplement use (P = .45). Mean serum VitD levels were 15.21, 13.16, and 13.37 ng/mL, respectively, before the surgery and reached 32.91, 24.74, and 29.49 ng/mL after 7 weeks of treatment in oral, injection, and combined groups, respectively. Finally, the 7-week oral treatment option had significantly higher levels of VitD (P value = .034).

Conclusion: VDD treatment with 50,000 units VitD capsule every week for 7 weeks before bariatric surgery yields a higher level of VitD. Based on our findings, injectable supplements are not recommended for VDD treatment.