Muno-IgY Supplementation Improves Respiratory Health, Immune Response, and Exercise-Induced Physiological Stress in Healthy Adults: A Randomized Controlled Pilot Study

Background/Objectives: Upper respiratory tract infections (URTIs) and exercise-induced immune perturbations are common in adults and may adversely affect quality of life, productivity, and physical performance. Immunoglobulin Y (IgY), a food-derived antibody with broad antimicrobial activity, has demonstrated immunomodulatory potential in preclinical and limited clinical studies. This study evaluated the effects of a multi-pathogen-specific IgY supplement (Muno-IgY) on respiratory health, immune and inflammatory markers, exercise-induced physiological stress, and gut microbiome composition in healthy adults. Methods: in this 12-week, double-blind, placebo-controlled trial, 28 healthy adults with a history of URTI were randomly allocated to receive Muno-IgY or placebo. URTI incidence, duration, and severity were recorded daily. Serum immune and inflammatory biomarkers were assessed longitudinally and in response to a standardized exercise challenge. Gut microbiome composition was analyzed using shotgun metagenomic sequencing at baseline and week 12. Safety and tolerability were assessed throughout the study. Results: URTI incidence was numerically lower in the Muno-IgY group compared with placebo (14.3% vs. 35.7%), with shorter average duration and fewer missed workdays (p > 0.05). Following an acute exercise challenge, Muno-IgY supplementation resulted in a significant increase in serum IgA at 24 h post-exercise (p = 0.022) and a significantly greater reduction in lactate dehydrogenase at 1 h post-exercise compared with placebo (p < 0.0001). Exploratory gut microbiome analyses revealed favorable directional shifts in microbial composition. Conclusions: In this exploratory pilot study, Muno-IgY supplementation was safe and associated with significant improvements in selected markers of exercise-induced immune response and muscle damage, alongside favourable trends in respiratory health and gut microbiome composition. These findings support further evaluation of Muno-IgY in larger, adequately powered clinical trials.