Zinc Fortification and Supplementation to Reduce Diarrhea in Children: A Literature Review

Background: Zinc deficiency is a major global health issue and appears to be responsible for risk of diarrhea and death, particularly in children under 5 years. This review therefore aimed to summarize the existing literature related to zinc supplementation and fortification for the prevention of diarrhea. Methods: In this literature review, we discussed the zinc-related biochemistry and pathophysiology of diarrhea and role of zinc in reducing the risk of diarrhea in children. Moreover, this literature review particularly analyzed studies published between 2014 and 2025, including systematic reviews, meta-analyses, and randomized controlled trials focusing on zinc fortification and supplementation for the prevention of childhood diarrhea. The studies covered a range of zinc dosing regimens (5–20 mg daily), preventive and therapeutic approaches, and combined interventions in children. Main outcomes such as diarrhea duration, severity, recurrence, growth, and side effects were assessed across diverse low- and middle-income populations. Results: Routine zinc supplementation helps to reduce all-cause diarrhea and respiratory infections. Zinc supplementation consistently reduced both the duration and severity of diarrhea in children. Also, diarrhea episodes and frequency were reduced in children taking zinc supplementation. Lower doses (5–10 mg) were mostly recommended to reduce vomiting. Combined zinc and vitamin A supplementation further improved outcomes, while long-term low-dose zinc supplementation prevented diarrhea and infections. Conclusion: This review confirms that zinc supplementation and fortification are effective, affordable strategies for reducing childhood diarrhea. Supplementation during diarrheal episodes reliably shortens duration and severity, with long-term benefits lasting for months. Continued research and integrated approaches for dosing and delivery are needed for both low- and middle-income countries.