Development of resting cardiovascular activity during the first 2 years of life differs in breastfed and formula‐fed boys and girls

Abstract

To investigate whether early infant diet influences cardiovascular development we recorded resting heart‐rate (HR) at 3, 6, 9, 12, and 24 mo in awake healthy children who were breastfed (BF) or fed milk formula (MF) or soy formula (SF) during infancy (n = 83–146/group/age). HR, and indices of autonomic nervous system (ANS) sympathetic [low frequency power (Plf: .04–.15 Hz)] and parasympathetic activity [high frequency power (Phf: .15–.5 Hz)] were determined from power spectral analyses of digitized, artifact‐free recordings and analyzed using ANOVAs with post‐hoc t‐tests. HR decreased and Plf and Phf increased for all groups across the study period. Few within‐group gender differences were found [6 mo Plf: MF girls > boys, p < .05; 12 and 24 mo HR: SF girls > boys, both p < .05]. There were three important diet‐related findings: 1) levels of Plf and Phf were higher in BF than formulafed (FF) groups after 6 mo (p < .001); 2) SF and MF infants did not differ on HR measures; 3) and, group differences were modulated by gender [greater Plf and Phf in FF than BF girls from 9–24 mo (p < .02) and in FF than BF boys at 12 and 24 mo (p < .01)]. Baseline levels of ANS activity influence interactions between the central nervous system and ANS that regulate attention, emotion, cognition and behavior. The present findings suggest early infant diet may contribute to individual differences in these functions.Supported by USDA ARS CRIS 6251‐51000‐006‐03S