The Role of Probiotics and Probiotic-Fortified Product Supplementation in Improving Nutritional Outcomes in Children under Five with Acute Malnutrition: A Systematic Review and Meta-Analysis of Randomized, Controlled Trials Protocol

Background: Acute malnutrition, including severe acute malnutrition (SAM) and moderate acute malnutrition (MAM), affects over 45 million children under five globally and remains a leading cause of childhood morbidity and mortality. Despite therapeutic feeding programs using ready-to-use therapeutic foods (RUTFs) and fortified blended foods (FBFs), relapse and suboptimal treatment outcomes persist. Emerging evidence links gut microbiota dysbiosis to impaired nutrient absorption and immune function in malnourished children. Probiotic supplementation has been proposed as a strategy to restore microbial balance, enhance intestinal health, and improve nutritional recovery. However, clinical trial evidence remains inconsistent, particularly for children with MAM. Methods: This protocol outlines a systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating the effects of probiotic or probiotic-fortified product supplementation in children under five diagnosed with SAM or MAM. Databases to be searched include PubMed, Embase, CENTRAL, CINAHL, Web of Science, and Scopus, along with clinical trial registries. Eligible studies will compare probiotic interventions with placebo, standard care, or no treatment. Primary outcomes include weight gain, weight-for-height z-scores (WHZ), mid-upper arm circumference (MUAC), recovery rate, and time to nutritional recovery. Two reviewers will independently conduct study selection, data extraction, and risk of bias assessment using the Cochrane Risk of Bias 2.0 tool. Random-effects meta-analyses will be performed where appropriate. Subgroup analyses (e.g., by strain, dosage, duration) and sensitivity analyses will address heterogeneity. Certainty of evidence will be assessed using the GRADE approach. Discussion: This will be the first systematic review to rigorously evaluate probiotic supplementation for both SAM and MAM populations using PRISMA2020 guidelines and GRADE methodology. Strengths include a focus on high-quality RCTs, comprehensive search strategies, and transparent bias and evidence quality assessments. Limitations may include variability in probiotic strains, formulations, dosages, and outcome measures, as well as limited subgroup data. Systematic Review Registration: This protocol is registered with PROSPERO with Registration: ID CRD420251091133