The Effects of a Healthy Diet on Asthma and Wheezing in Children and Adolescents: A Systematic Review and Meta-Analysis

Background: Asthma is a public health problem requiring focused attention. This study aimed to systematically evaluate the association between dietary structure and asthma or wheezing in children. Methods: The study protocol of this meta-analysis has been registered in the International Prospective Register of Systematic Reviews (PROSPERO) with the registration code CRD42023390191. A total of 8397 articles were retrieved, searching PubMed, Medline, Embase, Web of Science, and Scopus databases as of November 21, 2022. Two independent authors were responsible for independently conducting the literature screening process. Effect-size estimates were expressed as odds ratio (OR) in cross-sectional studies and risk ratio (RR) in cohort studies with a 95% confidence interval (CI). Summary effect estimates were evaluated with random-effect models. Meanwhile, subgroup and sensitivity analyses were performed to assess the potential sources of heterogeneity and the robustness of the pooled estimation. Results: A total of 65 studies, including 567,426 subjects had been analyzed. Overall analyses of cross-sectional studies revealed that a healthy diet was protective against asthma (adjusted OR=0.85, 95% CI: 0.80-0.89, P <0.001, I-2=69.8%, Tau(2)=0.026) and wheezing (adjusted OR=0.85, 95% CI: 0.81-0.89, P <0.001, I-2=66.8%, Tau2=0.015) in children and adolescents. Conversely, unhealthy diets can exacerbate asthma (adjusted OR=1.28, 95% CI: 1.20-1.36, P <0.001, I-2=64.9%, Tau(2)=0.019) and wheeze (adjusted OR=1.09, 95% CI: 1.02-1.16, P =0.006, I-2=75.2%, Tau(2)=0.023) in children and adolescents. The same trend was found in cohort studies (adjusted RR=0.72, 95% CI: 0.58-0.90, P =0.003, I-2=83.5%, Tau(2)=0.105). A clear trend was observed between high-frequency healthy diets (OR=0.80; 95% CI: 0.71-0.89; P <0.001) is more protective against asthma than low-frequency healthy diets (OR=0.81; 95% CI: 0.70-0.94; P =0.007). Conclusion: Our findings highlight the protective effects of a healthy diet on asthma and wheezing in children, including fruit, seafood, cereals, and the Mediterranean diet.