Infant gut peptide response to feeding diets differing in composition
Date
2015
Authors
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Journal ISSN
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Publisher
University of Delaware
Abstract
Background: Evidence indicates that the composition of an infant's diet in early life affects their growth rate. Formula fed (FF) infants, the majority of whom are fed a cow milk (CMF) infant formula, have been shown to gain weight at a faster rate and weigh more than breast fed (BF) infants by the end first year of life. These early growth differences have important implications for future health; infants with accelerated growth rates and more rapid weight gain are at greater risk for obesity and related diseases in child- and adulthood. Interestingly however, a recent study of formula fed infants found that infants fed an extensive protein hydrolysate formula (ePHF) grew at a more normative rate and consumed less formula to satiation compared to infants fed CMF. That infants consumed significantly less volume per feeding and satiated earlier when feeding ePHF as compared to CMF suggested that the composition of formula, not bottle feeding alone, plays a role in energy intake and therefore growth. Energy intake is controlled by complex signals from the peripheral systems including the gut, which act on the central nervous system (brain) via neural and endocrine pathways. Gut and other peripheral hormones signal energy needs, fat stores, hunger, satiation and satiety. We postulate that a possible method to explain the differential growth between formula and breast fed infants and between some groups of formula fed infants, could be the gut peptide response to diet composition, which in turns leads to differences in satiation, and in turn energy intake. Differential gut peptide response to diets of different macronutrient composition would impact feelings of fullness, meal termination, energy intake, and ultimately weight gain and growth. Gut peptide response to feedings of different composition in healthy infants is a relatively unexplored topic. Statement of Problem: A better understanding of the gut peptide response to diets of different composition in infants may provide insights into observed differences in satiation and growth. Peptide response to feeding has not been studied sufficiently in healthy, term infants, nor has the effect of diet composition (CMF, ePHF, breast milk) on gut peptides been explored. Aims: The purpose of the within-subject study was to 1) use a model system that experimentally manipulates diet by feeding formulas of different macronutrient composition to study biomarkers of satiation and satiety during a typical formula feeding and 2) study biomarkers of satiation and satiety during a typical breast milk feeding. The primary aim of this study was to determine if gut peptide concentrations differ at the beginning compared to the end of a formula feeding and determine if the patterning of gut peptide response (the change in concentration) differs based on the formula fed (the condition: CMF, ePHF). The secondary aim of this study was to determine if gut peptide concentrations differ at the beginning compared to the end of a breast milk feeding and determine if the patterning of gut response is consistent within subjects. An exploratory aim of this study was to determine if the concentrations of gut peptides prior to a feeding are stable within subjects, regardless of the mode of feeding (formula vs. breast). Design and Analysis: This ongoing study is a within-subject, between-subject pilot study of healthy, term infants who are either exclusively formula-fed or exclusively breast-fed. Mother-infant pairs participate in two study visits within a 7-day period, during which intake, duration of feeding, and biomarkers of satiation and satiety are assessed using an infant-led feeding paradigm. Because this study is on going; the current data analysis mainly consisted of summary and descriptive statistics to assess means and variability as well as preliminary trends. Future analyses will be performed as sample size increases. Results: In formula fed infants, gut peptide concentrations at the beginning of a feeding were significantly lower compared to the end of a feeding for neuropeptide YY (PYY), glucagon-like peptide-1 (GLP-1) and gastric inhibitory peptide (GIP). Ghrelin and leptin concentrations did not significantly differ from the beginning to the end of a feeding. The relative change in peptide concentrations did not differ by the type of formula fed (CMF, ePHF). In breast fed infants, PYY, GLP-1, GIP and leptin concentrations were significantly lower at the beginning of a feeding compared to the end of a feeding. Ghrelin concentrations did not differ from the beginning to end of a feeding. The relative change in gut peptide concentrations was stable within breast fed infants for GLP-1, GIP, ghrelin and leptin. In all infants, the concentrations of PYY and leptin prior to feeding on day 1 were significantly correlated with concentrations prior to feeding on day 2. (Abstract shortened by UMI.)