The Efficacy and Safety of Probiotics for Allergic Rhinitis: A Systematic Review and Meta-Analysis

Frontiers in Immunology
Q1
May 2022
Citations:46
Influential Citations:5
Systematic Reviews / Meta-Analyses
93
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Methods
Systematic review and meta-analysis of randomized controlled trials. Participants with allergic rhinitis aged 2–65 years (SAR and PAR), including both adults and children; 15 adult-only trials, 11 pediatric trials, 2 mixed-age trials; 28 trials overall.
Intervention
Regimens varied across trials; oral probiotic regimens were delivered as capsules, yogurt, fermented milk, probiotic drinks, or powders. Daily doses ranged roughly from 1×10^7 to 1×10^12 CFU; durations spanned about 4 weeks up to 12 months; some regimens used live bacteria while others used heat-killed preparations; several studies combined probiotics with antihistamines (e.g., loratadine or levocetirizine) or with other AR therapies.
Results
Probiotic supplementation significantly improved allergic rhinitis symptoms (SMD −0.29; 95% CI −0.44 to −0.13; p=0.0003) and reduced Rhinoconjunctivitis QoL scores (SMD −0.64; 95% CI −0.79 to −0.49; p<0.00001). It favored a healthier Th1/Th2 balance (MD −2.47; 95% CI −3.27 to −1.68; p<0.00001). No significant changes in total IgE (SMD −0.03; 95% CI −0.18 to 0.13) or antigen-specific IgE (SMD 0.09; 95% CI −0.16 to 0.34; p=0.49). Subgroup analyses suggest stronger symptom relief in seasonal AR and potential greater benefit with probiotics used alone (monotherapy). However, high heterogeneity across studies and very low to low quality of evidence temper confidence; clinicians should be cautious in recommending probiotics for AR and more standardized trials are needed.
Limitations
High heterogeneity across trials (e.g., I2 up to 97%), varied probiotic strains/doses/durations, and some unclear risk of bias; small sample sizes in several trials; pollen exposure and regional differences may confound results; mixed reporting of adverse events; overall GRADE ratings for key outcomes were very low to low.

Abstract

Background Probiotics have proven beneficial in a number of immune-mediated and allergic diseases. Several human studies have evaluated the efficacy and safety of probiotics in allergic rhinitis; however, evidence for their use has yet to be firmly e...