Comparison of Micronutrient Deficiencies Following Roux-en-Y Gastric Bypass and One-Anastomosis Gastric Bypass

Introduction: Obesity is a chronic disease that can be effectively managed with bariatric surgery, such as gastric bypass. Both Roux-en-Y gastric bypass (RYGB) and one-anastomosis gastric bypass (OAGB) surgeries are associated with malnutrition. OAGB is associated with higher weight loss and remission of diabetes. However, it is also associated with a significantly greater incidence of malnutrition than RYGB. We conducted this study to assess the association of both procedures with different micronutrient deficiencies. Methods: A retrospective single-center cohort study was conducted. Patients undergoing RYGB and OAGB between January 1, 2022, and June 30, 2023, were included. Micronutrient deficiencies following RYGB and OAGB were compared. Vitamin B12, vitamin D, ferritin, and folate levels were assessed preoperatively and between six months to one year after the surgery. Results: A total of 116 patients underwent gastric bypass surgery, from which 50 (43.1%) patients were excluded due to loss of follow-up, and 66 (56.9%) were included. There were 50 (75.8%) RYGB cases and 16 (24.2%) OAGB cases. There were 24 (36.0%) males. The mean age was 46.2 ± 9.6 years, and the mean preoperative body weight was 131.8 ± 27.9 kg. The mean height was 165.8 ± 9.9 cm, and the mean body mass index (BMI) was 47.7 ± 7.6 kg/m2. Both groups were comparable in age, gender distribution, and height. However, patients' mean weight in the OAGB group was higher than in the RYGB group, with a correspondingly higher BMI. Folate deficiency was more common following OAGB (30.8%; N = 4) than RYGB (8.0%; N = 4) (p = 0.028). A fall in folate levels from the initial value was found in the OAGB group, while a rise was found in the RYGB group. However, the two groups had no statistically significant differences in vitamin B12, vitamin D, and ferritin deficiencies (or fall from the initial values). Conclusion: Both RYGB and OAGB are associated with micronutrient deficiencies. However, OAGB is associated with an increased incidence of micronutrient deficiencies compared to RYGB after six months to one year following the surgery, especially folate deficiency (p = 0.028). Larger, prospective studies and randomized controlled trials are needed, with standardization of the BP limb, the inclusion of multiple ethnicities, and longer follow-up periods.