Efficacy of probiotics as adjuvant therapy in bronchial asthma: a systematic review and meta-analysis

Background: Asthma is a chronic, heterogeneous disease characterized by airway inflammation. Asthma exacerbations significantly increase the disease burden, necessitating new therapeutic approaches. Emerging evidence suggests probiotics, through the gut-lung axis, may benefit asthma management by modulating immune responses and reducing inflammation. Methods: This systematic review and meta-analysis adhered to PRISMA guidelines and was registered with PROSPERO (CRD42023480098). A comprehensive search of PubMed, Scopus, Web of Science, and Embase was conducted up to March 2024. Inclusion criteria encompassed randomized controlled trials (RCTs) evaluating probiotic interventions in asthma patients. Statistical analysis was done using RevMan 5.3, with odds ratios (OR) and 95% confidence intervals (CI) calculated, and heterogeneity assessed using I² statistics. Results: Twelve RCTs, comprising 1401 participants, met the inclusion criteria. The probiotic strains investigated included various Lactobacillus and Bifidobacterium species. Meta-analysis revealed significant improvements in asthma control test scores (OR 1.18, 95% CI: 1.18–3.64, p = 0.0001) following probiotic supplementation. Probiotics also improved fractional exhaled nitric oxide (FeNO) in one study, but pooled FeNO and eosinophil data were not statistically significant (p = 0.46 and p = 0.29, respectively). One study observed fewer asthma exacerbations in the probiotic group (24/212) compared to placebo (67/210), with no difference in exacerbation duration. Conclusion: Probiotic supplementation may be beneficial in improving asthma symptom control with no significant impact on lung function indices or eosinophil levels. Probiotics can be a potential adjunctive therapy in asthma management, particularly for asthma symptom control.