Submitted to: Journal of Pediatric Gastroenterology and Nutrition
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/29/1997
Publication Date: N/A
Citation: Interpretive Summary: There is concern that as premature babies grow they deposit a disproportionate amount of fat compared to lean tissue. We wanted to find out whether commercial formulas that are custom-made for premature babies ought to have a higher protein-to-energy ratio -- in other words, whether they should contain additional protein based on the concept that additional lprotein might help these growing babies acquire a higher proportion of lea tissue. With that in mind, we added extra protein to a commercial formula and fed it to prematurely born babies for three weeks and then performed energy and nutrient balance studies to determine their body composition. The higher-protein formula did not make a difference in the babies' fat-to-lean tissue ratio. Even though the babies took in more nitrogen, they didn't retain any more nitrogen or minerals required to make lean tissue.
Technical Abstract: Although standard preterm formulas promote intrauterine rates of weight gain, fat deposition of preterm infants has been reported to be considerably higher than that of the fetus. To achieve proportional fetal accretion rates of fat and fat-free mass, a preterm formula with a higher protein:energy ratio (3.2 g/100 kcal) was fed at 120 kcal.kg-1.d-1 to 8 very-low-birth-weight, preterm infants for a period of 3 weeks. A control group (n=7) was fed isocalorically a preterm formula with a protein:energy ratio of 2.6 g/100 kcal. At the end of the study period, a 72-h energy and nutrient balance study was performed. Despite the higher intake and net absorption of nitrogen by infants fed the higher protein:energy formula, there was no difference in net nitrogen retention between groups. There also were no statistically significant differences between groups in digestible energy, metabolizable energy, energy expenditure or energy storage. Partitioning of stored energy as protein and fat did not differ between groups. The retention of calcium, phosphorus, sodium, potassium, copper, zinc, and iron did not differ between groups, and nitrogen intake did not affect mineral retention. In this study, preterm formula with a protein:energy ratio of 3.2 g/100 kcal vs. 2.6 g/100 kcal provided no apparent benefit in terms of the proportion of fat to lean tissue accretion.