The findings also revealed beneficial changes in the microbiota and immune markers.
“As early life may represent a critical window for immune and microbial development, such targeted probiotic interventions may offer a safe and effective approach to support infant health and resilience against infection and inflammation,” wrote researchers in China and Malaysia.
The researchers were also evaluating respiratory outcomes, which didn’t remain statistically significant, highlighting a need for further studies in this area.
The critical window for shaping the microbiota. The early postnatal period is a critical time for establishing the gut microbiota, which influences physiological, metabolic, and immune development.
The results of early-life bacterial colonization can influence lifelong health and susceptibility to respiratory infections, allergies, and immune-mediated diseases later in life.
Because delivery mode and antibiotics can reduce beneficial bacteria such as Bifidobacterium, infants born by caesarean section or exposed to antibiotics may benefit from probiotics that help modulate the microbiota.
In addition to supporting gut health, probiotics may influence respiratory health through the gut–mucosal axis. The mechanisms may include increasing sIgA, the body’s first line of defense, protecting the epithelium from pathogens and toxins, and supporting tolerance to infections.
The current study noted that B. infantis YLGB-1496 “contributes to immune microbiota cross talk that reinforces intestinal barrier integrity, enhances mucosal antibody production, and prevents dysbiotic transitions, thereby supporting both GI and respiratory health in early infancy.”
Study details
Researchers randomized 119 healthy infants aged under a year to receive one daily sachet of B. infantis YLGB-1496 (1 × 10¹⁰ CFU) or placebo for 12 weeks.
They assessed respiratory and gastrointestinal health using questionnaires and collected oraland fecal samples to analyze microbiota and inflammatory markers.
The results did not reveal statistically significant reductions in respiratory symptom days, but did show “robust improvements” in gastrointestinal outcomes, including reduced stomach ache, lower incidence of diarrhea, and fewer diarrhea-related clinical visits in the B. infantis group.
Fecal sIgA markers remained elevated, and TNF-α remained stable in the intervention group compared to placebo.
The researchers noted that “the sustained sIgA levels suggest enhanced mucosal protection” and the TNF-α results reflect “a shift toward immune modulation and controlled inflammation.”
Beneficial bacterial species were increased in the intervention group, whereas bacteria associated with dysbiosis and inflammation were increased in the placebo group.
“Collectively, these findings demonstrate that B. infantis YLGB-1496 promoted a gut microbiota profile enriched in barrier-supporting and anti-inflammatory bacteria, whereas the placebo group displayed trends consistent with dysbiosis,” the researchers wrote.
They recommended future research with extended follow-up to provide insight into sustained clinical outcomes.
Source: Front. Nutr, https://doi.org/10.3389/fnut.2026.1746679, “Probiotic improves respiratory and gastrointestinal health, immune homeostasis, and gutmicrobiota composition in infants: a randomized controlled trial.” Authors: M. U. Mageswary.
