Effect of Infant Formula Made With Milk Free of A1-Type β-Casein on Growth and Comfort: A Randomized Controlled Trial

Consumption of milk free of A1-type β-casein (A1PF) can result in reduced gastrointestinal/inflammatory symptoms versus conventional milk (containing A1- and A2-type β-casein; CON); however, the comparative effects of infant formula made with these milks are unknown. This study compared growth, gastrointestinal tolerance, and crying frequency/duration in healthy Chinese infants aged 3-4 months who consumed both breastmilk and A1PF or CON infant formula. This open-label, randomized, controlled trial conducted between July and November 2023 evaluated anthropometric measurements and comfort (Infant Gastrointestinal Symptom Questionnaire [IGSQ] and frequency of crying) of mixed-fed infants who also consumed A1PF or CON infant formula. Eczema/dermatitis severity, quality of life, satisfaction with the formula, and adverse events were also assessed. In the A1PF (n = 140) and CON groups (n = 140), the mean (standard deviation) ages were 100.83 (15.01) and 99.28 (13.15) days, respectively. There were no significant between-group differences in any anthropometric measurements. At Weeks 2 and 4, the A1PF group had significantly lower mean daily total IGSQ scores; lower mean stooling, spitting up/vomiting, crying, and fussiness domain scores; and fewer daily crying episodes than the CON group (p < 0.05). From satisfaction surveys, a significantly higher percentage of the A1PF group had relieved gastrointestinal symptoms, reduced vomiting after feeding, improved digestion, and better stool characteristics (p < 0.05). Both formulas were generally well tolerated. Among mixed-fed infants, those who consumed A1PF infant formula had the same growth as those fed CON infant formula, and improved comfort (including relieved gastrointestinal symptoms and fewer crying episodes). Trial Registration: ClinicalTrials.gov, NCT06256094.