Probiotic formula cut baby infections 41%?

Claim

FORMULA CUTS INFECTIONS 41%

Catch

NEWS: 23% VS 40%

Verdict

PROMISING NOT PROVEN

The study: 240 healthy term infants, exclusively formula-fed, enrolled August 2023–February 2024 at three hospitals in metropolitan Manila, Philippines. Babies aged 14–35 days were randomized 1:1 to a synbiotic formula (seven human milk oligosaccharides + bovine milk oligosaccharides + Bifidobacterium longum subsp. infantis LMG11588) or standard bovine-milk formula, for 6 months. Parents, care providers, investigators, lab personnel, data analysts and sponsor staff were all blinded. 223 infants made the full analysis set (109 synbiotic, 114 control); 217 (90%) completed the study.

The finding: B. infantis colonization was virtually 100% in the synbiotic group from 2 months, versus barely detectable in most controls. Fecal pH was lower, calprotectin and alpha-1-antrypsin lower, secretory IgA higher. Upper respiratory tract infection episodes fell 41% per child-year (incidence rate ratio 0.586; 95% CI 0.356–0.954; p=0.031). Serious adverse events were even: 4 events in 4 infants per group, including one death (aspiration pneumonia) in the control group, unrelated to the study. Growth was non-inferior.

The catch, part one — the headline number doesn't match the paper's table. The widely reported version said "23% of babies in the supplement group were recorded as developing an infection, compared with 40% in the formula-only group." The paper's Table 2 (Infections and infestations as adverse events) actually reports upper respiratory tract infection in 18 of 109 infants (16.5%) in the synbiotic group versus 28 of 114 (24.6%) in controls. The larger 23%/40% figures come from 25 and 46 infection episodes (19 URTI + 6 viral URTI, and 41 + 5) divided by infant counts — episodes counted against children. A baby with two snuffles is two episodes, not two babies.

The catch, part two — the endpoint, the sponsor and the peer review. Infections were not a pre-specified endpoint. The trial's registered primary outcome was growth (weight gain); infection was captured only as a reported adverse event, which the authors say leaves it "susceptible to differential ascertainment and recall bias across sites and visits." The trial was not powered for subgroup effects, the immune sub-study enrolled only 86 of 240 infants first-come first-served, and the multi-component design can't separate the HMOs, bovine oligosaccharides and probiotic. It ran in one urban Philippine cohort with very low baseline B. infantis, so results "cannot be assumed to generalize uniformly." The paper is a medRxiv preprint and has not been peer reviewed. The trial was sponsored by Société des Produits Nestlé S.A. (which manufactures infant formula); six authors are Nestlé employees, and Nestlé scientists were involved in study design, data collection, analysis, interpretation and manuscript preparation. Total infections and infestations as adverse events were similar (39.4% vs 42.1%), and the "babies recovered faster" claim was a trend, not a significant difference (p=0.07). The authors state the trial "does not establish any associations with long-term protection against allergy, infection, or immune-mediated disease."

Bottom line: a promising, well-blinded signal from a formula company-funded trial — with a headline number derived loosely, and not yet a reason to change what your baby drinks. Talk to your pediatrician, and read the preprint and trial registration before treating the 41% as settled.

SOURCES

1. Chen Q, Chung CK, Capeding MRZ, et al. "A Synbiotic Infant Formula Promotes Balanced Immune-Microbiome Interactions in Term Infants: A Randomized Controlled Trial." medRxiv preprint, posted 7 October 2026. DOI: 10.64898/2026.10.05.26364773 (not yet peer reviewed). Table 2, p. 9.
2. ClinicalTrials.gov NCT06073652 — "Safety and Efficacy of a Starter Infant Formula With Synbiotics" (sponsor: Société des Produits Nestlé S.A.). Registered primary outcome: growth/weight gain. Status: active, not recruiting; estimated completion September 2027.
3. Wong C. "Probiotic cuts risk of respiratory infections in formula-fed babies." New Scientist, 15 October 2026.
4. Poindexter B; AAP Committee on Nutrition; AAP Clinical Reports Executive Committee. "Use of Probiotics in Preterm Infants." Pediatrics. 2021;148(1):e2021051485. DOI: 10.1542/peds.2021-051485

Disclaimer: For information only, not medical advice. The trial does not establish that the formula prevents infections. If you are considering changing your baby's formula, or if your baby has feeding or health concerns, talk to your pediatrician first.