Effect of A1 protein-free formula versus conventional formula on acute respiratory infections and diarrhea in toddlers: A Randomized Controlled Trial.

Objectives: Acute respiratory infections (ARIs) and diarrhea are common in toddlers. Milk free of A1 β-casein (A1PF milk) may support the immune system, but few studies have investigated A1PF milk in toddler formula and any potential effects on ARI/diarrhea. This study's objective was to investigate the incidence of ARI and diarrhea with two toddler formulas, A1PF formula (A1PF) or conventional formula (CON), which differed in milk base and nutrient composition.

Methods: This randomized, open-label, multicenter study (19 December 2022 to 17 May 2023) evaluated the occurrence of ARI and/or diarrhea in toddlers (aged 2-3 years) who consumed A1PF or CON over 90 days.

Results: A total of 200 toddlers were enrolled, and 180 completed the study. The relative risk of ARI or diarrhea in the A1PF group versus the CON group did not differ significantly, but the median (interquartile range) ARI duration was significantly shorter in the A1PF group (3 [2-4] days vs. 5 [3-6] days, p = 0.012). At Day 90, toddlers consuming A1PF had significantly less severe bloating, gassiness, and fewer regurgitation events (all p < 0.05). Both formulas were well tolerated, and no serious adverse events were reported.

Conclusion: Toddlers who consumed A1PF had a reduced duration of ARI and improved diarrhea outcomes, reducing the burden on their families compared with toddlers who consumed CON. Although this is consistent with other studies, further research is required to determine whether these effects are solely attributable to the A1PF milk base or other differences between the formulas.