Submitted to: Developmental Neuropsychology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2008
Publication Date: 3/15/2009
Citation: Pivik, R.T., Dykman, R.A., Jing, H., Gilchrist, J.M., Badger, T.M. 2009. Early infant diet and the omega 3 fatty acid DHA: Effects on resting cardiovascular activity and behavioral development during the first half-year of life. Developmental Neuropsychology. 34(2):139-158.
Interpretive Summary: This is a report based on our long-term Beginnings study which looks at how what healthy babies eat affects their development. We studied measures of heart rate and behavioral development from ages 2 through 6 months in infants fed parent-selected diets in which a fatty acid (DHA) was naturally present (breast-milk), and either commercially added (milk- and soy-based formulas), or not (a soy-based formula). Feeding groups were alike in length of gestation, mother's IQ, family socioeconomic status, and showed similar mental and motor skills across the study period. Beginning at 4 months, heart rate in infants receiving the DHA-free diet was higher than that in other diet groups. These findings show that early dietary DHA affects heart rate control. The influence of this effect on later health and development warrants further study. In view of concerns about the safety of soy-formula on development, the absence of study effects specific to this formula is notable.
Technical Abstract: The course of postnatal maturation of cardiac control has implications for cognitive development, but the influence of early nutrition on underlying processes is still being defined. This investigation evaluated the effects of different diets on interactions among these variables during the first half-year of life in healthy, full-term infants enrolled in a longitudinal study of infant diet and development (the Beginnings study). Recordings of resting heart rate (HR) were obtained monthly from 2 to 6 months in infants belonging to one of four diet groups, i.e., those who were exclusively breast fed from birth (BF, n = 31), or fed formula with (milk-based: MF, n = 29; soy-based: SF, n = 30) or without (soy-based: SF-, n = 12) commercially supplemented DHA (decosahexaenoic acid). Formula-fed subjects must have been on their respective formulas since at least 2 months of age. Measures from all study variables were in the normal range for all groups across the study period, and there were few significant diet-related effects on cognitive and behavioral variables. Among significant HR-related findings was evidence of a substantial parasympathetic contribution to low-frequency power across groups. In infants fed the DHA-deficient diet higher HR and lower values for heart rate variability measures were observed, indicating decreased parasympathetic tone in this group. This effect appeared at 4 months and continued for the remainder of the study period. These data, and existing literature, suggest that the 3-5 month postnatal interval may be an important period in the development of cardiovascular regulation. Systematic relationships between cardiovascular development and behavioral development were not present across groups in this investigation. However, in SF- infants there was a pattern of outcomes across measurement domains unlike that present in the other groups that included significantly decreased parasympathetic tone and less marked developmental progression on cognitive measures. The absence of these effects in SF infants receiving the same based formula supplemented with DHA suggests that neither soy protein nor the associated phytochemicals in soy formula contribute to these effects to any appreciable extent. In general, the results do not indicate differences in any of the study variables attributable to soy formula per se. In discussing the results, consideration is given to the implications of the observed autonomic emphases for future development, as well as to a possible role of DHA in the early programming of autonomic regulation. It is possible that the effects observed represent transient variations related to the dynamics of this developmental period that are without further consequence. Whether this is the case or whether these results reflect events that may redirect future development may be determined as this longitudinal study progresses.