Prebiotics and Synbiotics in Asthma: An Integrative Review of Human Trials and Murine Meta-Analysis

Background/Objectives: The objectives of this study were to systematically review the literature on the effects of prebiotics and synbiotics on asthma control, lung function and asthma-associated inflammation from murine and human trials. Methods: A systematic review was performed following the PRISMA guidelines across multiple databases. A meta-analysis was performed on murine trials assessing asthma-associated inflammation and airway hyperresponsiveness, whilst a narrative review of human studies assessed asthma control, lung function, and inflammation. Results: Seventeen studies met the eligibility criteria for inclusion; eleven murine studies were included for meta-analysis and six human studies were for narrative review. The meta-analysis revealed significant effects of prebiotics and synbiotics on multiple markers of asthma-associated inflammation. Prebiotic intervention significantly reduced airway hyperresponsiveness (AHR) and type 2 cytokines (IL-4, IL-5, IL-13) and various cell counts, including neutrophil, macrophage, lymphocyte, eosinophil, and total bronchoalveolar (BALF). Synbiotics were also effective in reducing type 2 cytokines, including, IL-4, IL-5, IL-13, and lymphocytes, eosinophils, and total BALF cell count. A narrative review of human intervention trials of prebiotics and/or synbiotics revealed improvements in lung function, asthma control, and systemic and airway inflammation. Conclusions: This review indicates that dietary prebiotics and synbiotics may be suitable adjunct treatments to support asthma management, but further well-controlled human RCTs are required.