Impact of Zinc Supplementation in Adults With Chronic Kidney Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Abstract Context Zinc deficiency is prevalent in people with chronic kidney disease (CKD) and has significant clinical implications. Previous systematic reviews have only evaluated the impact of zinc supplementation on a limited range of biochemical outcomes in people receiving hemodialysis. Objective In this analysis we sought to evaluate the impact of zinc supplementation on all outcomes in adults with CKD, including kidney replacement therapies. Data Sources We conducted a systematic search across Cochrane, MEDLINE, CINAHL, PubMed, Scopus, and Google Scholar to identify randomized controlled trials assessing any outcomes in adults with CKD. Data Extraction Three authors independently assessed trial eligibility, extracted data, and assessed the risk of bias using the Cochrane Risk of Bias Tool and the quality of evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology. Data Analyses We identified 41 studies, with 23 included in meta-analyses. In total, 176 outcomes were reported, of which 11 were meta-analyzed. Zinc supplementation resulted in a significant increase in body weight (weighted mean difference WMD, 2.52 kg; 95% CI, 1.58-3.45; P .00001), serum zinc (WMD, 24.96 µg/dL; 95% CI, 20.43-29.50; P .00001), high density lipoprotein cholesterol (HDL-C; WMD, 8.05 mg/dL; 95% CI, 0.22-15.88; P = .04), albumin (WMD, 0.38 g/dL; 95% CI, 0.07-0.69; P = .02), and dietary energy intake (WMD, 271.80 kcal; 95% CI, 172.70-370.90; P .00001). No significant difference was observed in body mass index, total cholesterol, triglycerides, creatinine, and dietary protein and zinc intakes. Qualitative synthesis suggests that zinc supplementation may improve gastrointestinal symptoms, intensity of pruritus, quality of life, and quality of sleep. Conclusions In patients with CKD, znc supplementation is associated with increases in body weight, serum zinc, high-density lipoprotein–cholesterol (HDL-C), albumin, and dietary energy intake. The current body of evidence is of low quality, highlighting the need for further high-quality research to substantiate these findings and for the translation of findings into clinical practice. Systematic Review Registration PROSPERO registration no. CRD42024574253.