Anorexigenic and orexigenic peptide response to feedings of different protein composition in healthy formula fed infants

Abstract

Rapid weight gain in infancy is a risk factor for later life overweight and obesity. Diet composition is a key factor affecting growth in infancy. Numerous studies show formula fed infants, the majority of whom are fed cow milk formula (CMF), gain more weight than breastfed infants in the first year of life; whereas infants fed extensive protein hydrolysate formula (EHF) have more normative growth, similar to breastfed infants, the gold standard for infant growth. Infants fed EHF have been shown to satiate at a lower volume and earlier than when fed CMF. The mechanism by which EHF leads to earlier satiation at a lower intake volume is unknown, however it is hypothesized the extensively hydrolyzed protein (small peptides and free amino acids) found in EHF formulas may lead to differential responses in the gastrointestinal peptides that play a role in meal termination (satiation). ☐ The overall aim of this study was to determine the effect of formula composition (EHF vs. CMF) on satiation and adiposity peptide response in healthy, formula fed infants. Infants (n=5 males, n=6 females) ages 1-4 months old were recruited from the greater Newark, Delaware area. Subjects completed 2 study visits within 7-days, and received one test formula, EHF or CMF, at each visit in random order. Blood samples were drawn pre-feeding and post-feeding at each visit to assess differences in peptide response by formula type. ☐ Infants were on average 86 days old (95%CI 70.7-101.4) and weighed 5.8kg (95%CI 5.3-6.4). Although the study was underpowered for all outcomes, preliminary analysis revealed there were no significant differences in the change in concentration of satiation and adiposity peptides by formula type. Further, there were no significant differences in infant feeding dynamics (volume, duration, or rate of feeding) by formula type, although volume and rate of feeding was lower for EHF feeds compared to CMF feeds in 8 of 10 infants. Duration of feeding was inversely correlated with change in PYY concentration, rate of feeding was positively correlated with change in PYY concentration, and time since last feeding was positively correlated with change in PYY and GIP concentrations for CMF but not EHF feeds. Current findings should be interpreted with caution and further analysis with a larger sample size is needed before definitive conclusions may be drawn.