Abstract
Objective: The aim of this study was to examine the safety and tolerance of Bifidobacterium longum subsp. infantis YLGB-1496 (B. infantis YLGB-1496) in toddlers with respiratory illness. Methods: In this randomized controlled trial, 120 toddlers with respiratory illness were randomly assigned to the probiotic (YLGB-1496) or control group for a 12-week intervention. Follow-up examinations were conducted at baseline (week 0) and at weeks 6 and 12 of the intervention. Toddlers' height and weight were measured by trained personnel, and defecation characteristics and gastrointestinal symptoms were recorded by parents or guardians. Stool samples were collected to determine the fecal pH, fecal calprotectin (FC) concentration, and fecal α1-antitrypsin (AAT) concentration. Results: A total of 115 toddlers completed the 12-week intervention (58 in the YLGB-1496 group and 57 in the control group). The height-for-age Z score (HAZ) in the YLGB-1496 group was significantly greater than that in the control group (p = 0.006). The weight-for-age Z score (WAZ) in the YLGB-1496 group increased between weeks 6 and 12, whereas the WAZ in the control group continuously decreased during the intervention. No differences in the frequency or consistency of defecation between the groups were observed. Toddlers in the YLGB-1496 group had lower incidences of poor appetite, nausea, vomiting, stomachache, lower abdominal pain, diarrhea, and dehydration (p < 0.05) but higher fecal AAT concentrations (p = 0.008) than did those in the control group. No differences in the fecal pH or FC concentration were observed between the groups. Conclusions: B. infantis YLGB-1496 demonstrated excellent safety and tolerability in toddlers and effectively reduced the gastrointestinal discomfort associated with respiratory illnesses.