Precision synbiotic intervention with 2'-fucosyllactose and infant-derived Bifidobacterium modulates gut-immune axis and reduces disease risk in toddlers: a randomized controlled trial.

Multicenter, double-blind, placebo-controlled, three-arm randomized trial

“In this multicenter, doubleblind, placebo-controlled, three-arm trial, 390 healthy toddlers were randomized (1:1:1) to receive (1) synbiotic (2’-FL 1.0 g/day + B. infantis R0033 1.5 × 109 CFU + B. bifidum R0071 1.5 × 109 CFU); (2) probiotic (identical strains/doses); or (3) placebo (maltodextrin 1.5 g/day) for 12 weeks, with 12-week follow-up.”

Healthy toddlers aged 1–3 years

“To determine the efficacy of a 2’-FL-containing synbiotic on infectious and atopic disease incidence, gut microbiota composition, and intestinal immune markers in children aged 1–3 years.”

390 participants randomized into three groups of 130 each

“A total of 390 children meeting the inclusion criteria were randomly assigned to one of the three groups: the combination of 2’-FL and probiotic intervention group (HPG), the probiotic intervention group (PG), and the placebo control group (CG) (130 children for each group).”

12 weeks of intervention followed by a 12-week follow-up period

“All subjects were supplemented for 3 consecutive months and then followed up for another 3 months.”

Synbiotic intervention significantly reduced the incidence of upper respiratory tract infections, pneumonia, diarrhea, and eczema compared to placebo

“Synbiotic vs. placebo: URTI incidence reduced from 85.4 to 55.4% (adjusted risk ratio (aRR) 0.64, 95% CI 0.43–0.95; ARR 30.0%, NNT = 3.3; p = 0.028); pneumonia from 17.7 to 7.7% (RR 0.40, 0.17–0.94; p = 0.034); diarrhea from 17.7 to 10.0% (aRR 0.54, 0.30–0.95; p = 0.032); and eczema from 13.1 to 1.5% (aRR 0.12, 0.04–0.35; ARR 11.6%, NNT = 2.9; p < 0.001).”

Synbiotic intervention altered gut beta-diversity and enriched specific Bifidobacterium species with HMO utilization pathways

“The synbiotic significantly altered gut beta-diversity (Bray-Curtis, p = 0.042) and enriched Bifidobacterium catenulatum and B. kashiwanohense species with conserved HMO utilization pathways.”

Synbiotic intervention reduced fecal calprotectin and increased secretory IgA levels at 24 weeks

“At 24 weeks, synbiotic reduced fecal calprotectin (62.7 ± 23.9 vs. 77.9 ± 24.6 μg/g; p = 0.004) and increased sIgA (1.37 ± 0.38 vs. 1.15 ± 0.49 mg/g; p = 0.014), indicating enhanced intestinal immune homeostasis.”

Limited generalizability due to single regional context, lack of detailed breastfeeding history, reliance on caregiver reporting, and insufficient power for low-incidence outcomes

“Firstly, the study population was drawn from defined community settings within a single regional context. Environmental exposures, dietary patterns, and baseline microbiota profiles may differ across populations, which may affect external generalizability. In addition, although all enrolled children were either exclusively formula-fed or had been fully weaned for at least 3 months before enrollment, detailed information regarding the duration of previous breastfeeding exposure was not systematically collected.”