Zinc status following different bariatric procedures: systematic review and meta-analysis.

INTRODUCTION: This study evaluated perioperative changes in serum zinc levels following different bariatric procedures and provided evidence-based recommendations for postoperative monitoring and supplementation. METHODS: PubMed, Embase, the Cochrane Library, Web of Science and CNKI were systematically searched from inception to July 2025. Eligible studies compared pre- and postoperative serum zinc levels in individuals with obesity undergoing bariatric surgery. Study quality was assessed using the Newcastle-Ottawa Scale (NOS), and the certainty of evidence was graded using the GRADE approach. Pooled analyses were conducted with StataSE 17.0. RESULTS: Twelve studies including 2,529 participants were analysed, with overall quality rated as high. Compared with baseline, pooled standardized mean differences (SMDs) in serum zinc at 3 months, 6 months, 1 year, and 2 years postoperatively were -0.12 (95% CI: -0.27 to 0.04, I2 = 57.9%, τ2 = 0.0265, p = 0.149), -0.36 (95% CI: -0.58 to -0.14, I2 = 82.2%, τ2 = 0.1043, p = 0.001), -0.35 (95% CI: -0.53 to -0.16, I2 = 81.9%, τ2 = 0.0769, p = 0.001), and -0.36 (95% CI: -0.95 to 0.24, I2 = 97.2%, τ2 = 0.3515, p = 0.240), respectively. Subgroup analysis showed no significant changes at 3 months across procedures. However, zinc levels significantly decreased at 6 and 12 months after Roux-en-Y gastric bypass (RYGB) and mini-gastric bypass (MGB), but not after sleeve gastrectomy (SG). At 2 years, no significant reduction was observed in any group. The certainty of evidence for zinc changes was rated as moderate. CONCLUSION: Serum zinc levels decline significantly during the first postoperative year, particularly after RYGB and MGB, while SG shows minimal impact. Routine zinc monitoring and individualized supplementation are recommended within the first year after surgery to prevent deficiency-related complications. REGISTRATION: https://www.crd.york.ac.uk/PROSPERO/view/CRD420251138846.