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Postoperative micronutrient changes in bariatric surgery patients compliant with nutritional supplementation

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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).


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.


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.


Patients in our sample did not have worsened micronutrient deficiencies following bariatric surgery, and there were no differences in micronutrient deficiencies between surgical technique.

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Editorial support was provided by Millie Hollandbeck (Phoenix, Arizona). The authors also acknowledge support from the 2021 SAGES Medical Student Research Award, which was granted to Mr. Rohan M. Shah.


This project was supported by the SAGES 2021 Medical Student Award.

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Correspondence to Lakhvir Kaur Sandhu.

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Lakhvir Sandhu and Rohan Shah have no conflicts of interest to disclose. Lakhvir Kaur Sandhu, Rohan M. Shah, Bipan Chand have no conflicts of interest or financial ties to disclose. Bipan Chand reports consulting fee, educational grant, travel, lodging, food and beverage reimbursements from W.L Gore, payments by Intuitive Surgical for education and Davol Inc for honoring him as a speaker.

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Sandhu, L.K., Shah, R.M. & Chand, B. Postoperative micronutrient changes in bariatric surgery patients compliant with nutritional supplementation. Surg Endosc 37, 8532–8539 (2023).

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