The Malnutrition-Infection Cycle in Children Under Five: A Systematic Review and the GROW-WELL Integrated Nutrition and WASH Model

Malnutrition and infection are closely interrelated in children under five, with inadequate nutrition increasing susceptibility to infection and illness further compromising nutritional status. Water, sanitation, and hygiene (WASH) conditions can intensify this cycle, yet nutrition and WASH interventions are often implemented separately. This review examines the evidence on the relationship between malnutrition and infection and the potential value of integrated approaches. A systematic review was conducted using searches of PubMed, ScienceDirect, Dimensions AI, and the World Health Organization repository. The review included 16 publications: 11 empirical studies and five policy documents. Two reviewers independently screened records, and methodological quality was assessed using the Mixed Methods Appraisal Tool (MMAT, 2018) for empirical studies and the Appraisal of Guidelines for Research and Evaluation II (AGREE II) instrument for policy documents. Findings were synthesized narratively. The included literature highlighted interconnected relationships among nutritional status, infectious disease, and environmental conditions, including inadequate water, sanitation, and hygiene. Nutrition-specific interventions and WASH measures addressed complementary pathways, although findings on the effectiveness of combined interventions were heterogeneous. The evidence therefore supports considering nutrition and WASH together while underscoring the need to account for contextual factors, implementation challenges, and differences in intervention design. Drawing on the synthesis, the review proposes the GROW-WELL integrated nutrition and WASH model to illustrate how coordinated actions could address multiple pathways contributing to the malnutrition–infection cycle. The findings highlight the importance of understanding malnutrition and infection as interconnected challenges and suggest that coordinated nutrition and WASH strategies warrant further investigation. GROW-WELL is an evidence-informed conceptual framework derived from the reviewed literature; it has not yet been validated through pilot implementation or empirical evaluation. Future research should assess its feasibility, acceptability, and effectiveness in diverse settings before conclusions about its practical impact can be drawn.