Neurodevelopmental Outcomes and Gut Bifidobacteria in Term Infants Fed an Infant Formula Containing High sn-2 Palmitate: A Cluster Randomized Clinical Trial

A few studies suggested high stereo-specifically numbered (sn)-2 palmitate in a formula might favor the gut Bifidobacteria of infants. The initial colonization and subsequent development of gut microbiota in early life might be associated with development and later life functions of the central nervous system via the microbiota-gut-brain axis, such as children with autism. This study aims to assess the hypothesized effect of increasing the amount of palmitic acid esterified in the sn-2 position in infant formula on neurodevelopment in healthy full-term infants and to explore the association of this effect with the altered gut Bifidobacteria. One hundred and ninety-nine infants were enrolled in this cluster randomized clinical trial: 66 breast-fed (BF group) and 133 formula-fed infants who were clustered and randomly assigned to receive formula containing high sn-2 palmitate (sn-2 group, n = 66) or low sn-2 palmitate (control group, n = 67), where 46.3% and 10.3% of the palmitic acid (PA) was sn-2-palmitate, respectively. Infants' neurodevelopmental outcomes were measured by the Ages and Stages Questionnaire, third edition (ASQ-3). Stool samples were collected for the analysis of Bifidobacteria (Trial registration number: ChiCTR1800014479). At week 16, the risk of scoring close to the threshold for fine motor skills (reference: scoring above the typical development threshold) was significantly lower in the sn-2 group than the control group after adjustment for the maternal education level (p = 0.036) but did not differ significantly versus the BF group (p = 0.513). At week 16 and week 24, the sn-2 group (week 16: 15.7% and week 24: 15.6%) had a significantly higher relative abundance of fecal Bifidobacteria than the control group (week 16: 6.6%, p = 0.001 and week 24:11.2%, p = 0.028) and did not differ from the BF group (week 16: 14.4%, p = 0.674 and week 24: 14.9%, p = 0.749). At week 16, a higher relative abundance of Bifidobacteria was associated with the decreased odds of only one domain scoring close to the threshold in the formula-fed infants group (odds ratio (OR), 95% confidence interval (CI): 0.947 (0.901-0.996)). Elevating the sn-2 palmitate level in the formula improved infants' development of fine motor skills, and the beneficial effects of high sn-2 palmitate on infant neurodevelopment was associated with the increased gut Bifidobacteria level.