Effects of Bifidobacterium infantis M-63 on gut environment and bowel function during weaning: RCT

BACKGROUND: Weaning involves rapid shifts in the gut microbiota, bowel irregularities, and increased infection risks. This exploratory, hypothesis-generating study examined whether daily supplementation with Bifidobacterium longum subsp. infantis M-63 (M-63) may influence bowel function, the gut environment, and general health during weaning. METHODS: In a randomized, double-blind, placebo-controlled trial, 100 healthy infants and toddlers (5 months to under 3 years) received M-63 (5 billion CFU) or placebo for eight weeks. Stool habits, fecal microbiota, and short-chain fatty acids (SCFAs) were assessed. Cold-like symptoms and medication use were recorded. Exploratory subgroup analyses considered breastfeeding status, age (