A comparison of the in vitro effects of 2-fucosyllactose and lactose on the composition and activity of gut microbiota from infants and toddlers

Because of the recognized health benefits of breast milk, it is recommended as sole nutrition source during the first six months of life. Among the bioactive components are human milk oligosaccharides that exert part of their activity via the gut microbiota. Here, we investigated the gut microbiota fermentation of 2 fucosyllactose using short-term fecal incubations and the long-term mucosal simulator of the human intestinal microbial ecosystem with fecal samples from three month-old breastfed infants as well as two - three year old toddlers. A key finding was the strong and immediate increase in the relative abundance of Bifidobacteriaceae following 2 fucosyllactose administration by fermentation by the breast feed infant and toddler microbiota in the M SHIME. At the metabolic level, while decreasing branched-chain fatty acids, 2 fucosyllactose increased acetate, propionate and butyrate whilst gas production only mildly increased. Notably, consistently lower gas production was observed with 2 fucosyllactose fermentation as compared to lactose, suggesting that reduced discomfort during the dynamic microbiome establishment in early life may be an advantage along with the bifidogenic effect observed.