Dietary intake influences gut microbiota development of healthy Australian children from the age of one to two years

Healthy children aged 12–24 months in Brisbane, Australia. The GUMLi trial was a double-blind randomized controlled trial comparing fortified milk with unfortified cow’s milk. The CHaRM longitudinal sub-study recruited 51 participants (48 completed); 29 female initially; 24 completers received GUMLi; dietary intake assessed with FFQs across five timepoints.

Fortified milk GUMLi containing Bifidobacterium breve M-16V probiotic and GOS/FOS prebiotics; 12-month trial; compared with unfortified cow’s milk.

Gut microbiota development in the second year of life shifted with age; alpha diversity increased (p<0.01) and overall richness/evenness expanded. Faecalibacterium increased, while Eubacterium, Veillonella, Oscillospira, Streptococcus, Eggerthella and Akkermansia decreased. Dietary patterns shifted from infant-like to adult-like diets; unprocessed foods correlated positively with certain Lachnospiraceae and Ruminococcus, while processed foods correlated with other Lachnospiraceae and Coprococcus. Consuming GUMLi synbiotic milk was associated with recruitment and expansion of Bifidobacterium taxa; the strongest discriminator was OTU132041, which rose with GUMLi intake and declined with age. Breastfeeding duration did not affect Bifidobacterium after covariate adjustment; attribution to probiotic B. breve M-16V vs GOS/FOS prebiotics requires further study. These findings support that the second-year diet can shape gut microbiota and that a synbiotic milk may promote beneficial Bifidobacterium colonization, potentially aiding microbiota maturation.

Small sample size with limited power to detect OTU-level significance; FFQ-based dietary assessment is less precise than detailed dietary records and was burdensome, limiting data collection; 12-month window and observational design within an RCT; cannot conclusively separate effects of probiotic B. breve M-16V from GOS/FOS prebiotics or milk matrix.