Specific probiotics in reducing the risk of acute infections in infancy – a randomised, double-blind, placebo-controlled study

Randomized, double-blind, placebo-controlled trial in infants needing formula before 2 months of age and not exclusively breast-fed. Participants were recruited from community well-baby clinics in Turku, Finland; infants with chronic disease were excluded.

Infants in the active arm received a daily oral probiotic supplement added to infant formula: Lactobacillus rhamnosus GG and Bifidobacterium lactis Bb-12, each at 1 x 10^10 colony-forming units per day, delivered in visually identical capsules and continued until 12 months of age. The placebo arm received matching capsules with formula supplementation under the same schedule.

Probiotic supplementation was associated with fewer acute infections and less antibiotic use during infancy, with the strongest signal in early and recurrent respiratory outcomes. Early infections within the first 7 months occurred in 7/32 (22%) versus 20/40 (50%) in placebo (RR 0.44, 95% CI 0.21 to 0.90; P = 0.014), antibiotic use in 10/32 (31%) versus 24/40 (60%) (RR 0.52, 95% CI 0.29 to 0.92; P = 0.015), and recurrent respiratory infections in 9/32 (28%) versus 22/40 (55%) (RR 0.51, 95% CI 0.27 to 0.95; P = 0.022). Tympanostomy was not statistically significant (0/32 vs 4/40; P = 0.066), and no serious adverse effects were observed. The authors concluded that the probiotic combination may reduce early acute otitis media, antibiotic use, and recurrent respiratory infections during the first year of life, but larger trials are needed.

The active arm was small, with only 32 infants randomized and 72 of 81 infants completing follow-up overall, limiting precision and safety inference. Several outcomes were not significant, including tympanostomy, and the findings come from a single setting in Turku, Finland, which may limit generalizability. The intervention was evaluated over the first year of life, so longer-term effects were not assessed.