Postoperative micronutrient changes in bariatric surgery patients compliant with nutritional supplementation

Background Bariatric surgery is commonly used in patients with body mass indexes over 35 kg/m and obesity-related comorbidities. Despite the significant clinical benefits of bariatric surgery, nutritional deficiencies post-surgery remain a challenge for both patient and healthcare provider [Toninello et al. in Nutrients 13:1565, 2021, Gasmi et al. in Eur J Nutr 61:55–67, 2022]. Nutritional supplementation is a way of reducing the likelihood of postoperative deficiencies; however, prior studies have shown varying degrees of mostly poor to moderate patient adherence [Spetz et al. in Obes Res Clin Pract 16:407–412, 2022, Mahawar et al. in Obes Surg 29:1551–1556, 2019, Santonicola et al. in J Am Nutr Assoc 41:11–19, 2022, Sherf Dagan et al. in Obes Surg 27:2258–2271, 2017]. Our present study aims to provide insights into the micronutrient biochemical profile in patients previously found to be compliant with supplementation following roux-en-y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG). Methods An 11-point outpatient survey was administered to consecutive patients ≥ 18 years who had undergone either RYGB or VSG to determine adherence with nutritional supplementation. Medical records were retrospectively reviewed to determine preoperative and postoperative lab values, including vitamins A, B1, B12, and D, thyroid stimulating hormone (TSH), iron binding capacity, transferrin, ferritin, folate, iron, albumin, hemoglobin A1C, zinc, glomerular filtration rate (GFR, and liver function values. Values were classified as “abnormal” or “normal.” Preoperative and postoperative values were compared for differences. Postoperative values were also compared between RYGB and VSG. Results There were no significant differences between preoperative and postoperative values for any nutritional marker aside from vitamin B12. A total of 51/60 patients (85.0%) had normal preoperative B12 measurements, compared with 40/65 (61.5%) patients postoperatively ( P = 0.03). Notably, of 25 “abnormal” postoperative measurements, 20 (80%) were elevated values. There were no differences in postoperative deficiencies between RYGB and VSG. Conclusions Patients in our sample did not have worsened micronutrient deficiencies following bariatric surgery, and there were no differences in micronutrient deficiencies between surgical technique. Graphical abstract