Author
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GILCHRIST, JANET - ACNC/UAMS |
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Submitted to: Pediatric Academic Society
Publication Type: Abstract Only Publication Acceptance Date: 1/15/2007 Publication Date: 5/5/2007 Citation: Gilchrist, J.M. 2007. Body composition reference data for exclusively breast-fed infants. Pediatric Academic Societies Annual Meeting, May 5-8, 2007, Toronto, Canada. Abstract E-PAS2007:61:7926.1. Available: http://www.abstracts2view.com/pas/view.php?nu=PAS07L1_2997. Interpretive Summary: Very little is known about body composition (% body fat) of infants. These data are important to estimate calorie needs and to measure normal growth of infants and children. Researchers need this data to study early diet and risk of disease later in life. Doctors need this data to measure the effects of their nutrition treatment. We are running a multi-site study to obtain data about the normal percent body fat of healthy, breast-fed infants. We see infants at 1 and 2 weeks, and 1, 2, 3, 4, 5, and 6 months of age and measure their percent body fat using a machine called the PeaPod. This machine measures an infant's weight on a scale and volume inside a "pod" of air. At all times studied, boys were bigger than girls, but they did not have more body fat. Percent body fat increased from 1 or 2 weeks to 1 month and again to 2 months. Percent body fat did not change from 2 months to 3, 4, or 5 months. Our data is different from others who have looked at infant percent of body fat. First, we did not see a difference between boys and girls. Second, percent body fat was lower in our study than others. This may be because we only studied breast-fed babies and others have studied babies who were breast-fed or formula-fed. Data from our Beginnings study also show a difference between body fat of breast-fed and formula-fed babies. Our new data for breast-fed babies is important. It offers a value for "normal" body fat when babies are healthy, full-term, and exclusively breast-fed. Technical Abstract: Limited data are available on the body composition (BC) of infants. BC reference data are needed to estimate energy and nutrient requirements; to evaluate normal growth and nutritional status of pediatric populations; for clinical research studies of the relationship between early diet and risk of chronic diseases in order to compare results to a normal or optimal BC standard; and in the clinical setting for assessing adequacy of nutritional interventions for various medical conditions. We are conducting a multi-site study to develop prescriptive normative reference data for BC in exclusively breast-fed (BF) infants from birth to 6 months. Infants (n = 47 female, 33 male) were seen at 1 and 2 wks, and 1, 2, 3, 4, and 5 months for body composition assessment by using air displacement plethysmography (PEA POD, Life Measurement, Inc., Concord, CA). We observed sex differences in body mass and lean body mass at all time points (males > females, p < 0.001), but no sex difference in percent body fat (%Fat) (p = 0.407). %Fat increased (p < 0.001) from 1 and 2 wks (11.8% and 13.4%, respectively) to 1 mo (18.0%), and 2 mo (23.0%), but was not significantly different between 2 and 3, 4, or 5 mo (24.8, 24.4, and 28.3%, respectively). Although our data are similar to those previously published by Fomon et al. (1982) and Butte et al. (2000), several key differences are notable. First, unlike earlier studies, we did not observe a sex difference in %Fat at any time point. Second, %Fat at 3-mo was lower in our sample than that of Butte et al., whose sample included both breast-fed (BF) and formula-fed (FF) infants. Data from our on-going longitudinal cohort study, Beginnings, suggest that body composition (assessed by PEA POD and DXA) does differ significantly between BF and FF infants in the first 6 mo of life. Our new BC data for exclusively BF infants adds to the existing literature and may serve as a clinical and research reference for those interested in a prescriptive standard for how infants should grow when provided with care that meets the current public health recommendations (e.g., healthy, full-term, pregnancy; exclusive BF for at least 4 months; non-smoking environment). |
