Nutrition and Gut Microbiome in the Prevention of Food Allergy

Background: Food allergies are increasingly recognized as a global health concern, influenced by early-life nutrition and the gut microbiome. This systematic review examined randomized controlled trials from 2005 to 2025 assessing the effects of probiotics, prebiotics, and synbiotics in preventing food allergies. Methods: Fourteen studies involving 5685 participants, including pregnant women, infants, and children with or without diagnosed food allergies, were analyzed. While several interventions demonstrated modulation of gut microbiota and immune responses, most trials reported no statistically significant reduction in IgE-mediated food allergy compared with placebo. Results: Some evidence suggested benefits from early exposure to allergenic foods and specific probiotic strains, such as Lactobacillus rhamnosus GG, particularly in cow's milk allergy. However, heterogeneity in study designs, strains, dosages, and diagnostic criteria limited generalizability. Conclusions: Overall, microbiome-targeted nutritional interventions show biological plausibility but inconsistent clinical efficacy. Future large-scale, standardized, and mechanistic studies integrating microbiome, genetic, and environmental data are warranted to define optimal strategies for allergy prevention.