Trends in Serum Vitamin D Levels within 12 Months after One Anastomosis Gastric Bypass (OAGB)

To assess serum vitamin D trend from baseline to 12 months after one anastomosis gastric bypass (OAGB).

In this observational cohort analysis of longitudinal data, we assessed the trend of serum vitamin D, and its associations with anthropometric, and biochemical measurements in 98 patients undergoing OAGB in a bariatric surgery center. All participants were on >800 IU/day vitamin D supplementation.

Vitamin D, lipid profile, creatinine, and albumin levels significantly improved at 12 months post-surgery. Vitamin D concentrations significantly increased from 26.52 ± 12.32 to 54.52 ± 27.90 ng/mL at 12 months. The correlations between vitamin D concentrations and weight, body mass index, lipid profile, ferritin, glycemic indices, and albumin were not significant. In addition, the correlations between vitamin D and parathormone, vitamin D receptor, calcium, phosphorus, body composition, and basal metabolic rate (BMR) did not reach the threshold of statistical significance at 12 months following bariatric surgery. Although there was a significant correlation between body weight and body composition (P < 0.001) and basal metabolic rate (BMR) (r = 0.762, P < 0.001) at 12 months, there were no significant correlations between weight change percent and body composition (P > 0.05), BMR (r = −0.101, P = 0.350), and vitamin D (r = 0.120, P = 0.271) at 12 months.

Our results showed that supplementation of vitamin D with dosage of >800 IU/day is sufficient for prevention of vitamin D deficiency within 12 months after OAGB surgery.