Effect of zinc supplementation on premenstrual symptoms: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to evaluate the efficacy of zinc supplementation for alleviating premenstrual symptoms (PMS) in women of reproductive age. A literature search was conducted across six electronic databases. Five randomized controlled trials were included in the qualitative synthesis and four were eligible for meta-analysis. All studies had some concerns for risk of bias. The certainty of the evidence was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation framework. Zinc supplementation reduced total PMS scores and emotional symptoms with moderate certainty of evidence, while physical symptoms were supported by low certainty of evidence. Meta-analyses revealed that zinc supplementation significantly reduced total PMS scores (Hedges's g =  -0.384), emotional symptoms (g =  -0.347), and physical symptoms (g =  -0.512), all favoring the intervention. Sensitivity analyses confirmed the robustness of results for the total and emotional domains, but the effect sizes for physical symptoms were moderately influenced by individual studies. In conclusion, zinc supplementation shows promise as a non-pharmacological intervention for reducing PMS. However, its generalizability is limited by the small number of trials and methodological heterogeneity. Further, multicenter RCTs with standardized protocols are warranted to establish clinical utility and explore dose - response relationships.