15N tracer studies of protein metabolism in low birth weight preterm infants: a comparison of 15N glycine and 15N yeast protein hydrolysate and of human milk- and formula-fed babies.
Nitrogen flux and protein synthesis and degradation were estimated using a single oral bolus of 15N glycine or 15N yeast protein hydrolysate and measuring the 15N enrichment of urinary ammonia in five low birth wt infants fed a low birth wt formula and in six who were receiving their own mother's breast milk. Results derived from using 15N-glycine and 15N-yeast hydrolysate tracers in a randomized crossover study in 10 studies on seven infants showed, with one exception, higher turnover rates and more interindividual variation with the 15N yeast. Both tracers showed good reproducibility in two infants who had repeated studies. Although wt gain was similar in both groups, nitrogen intake and retention were greater (p less than 0.01) in the formula-fed group. Mean nitrogen turnover was similar in both groups, but there was a greater variance in the human milk-fed group which also had a greater nitrogen turnover/U absorbed nitrogen (p less than 0.025) and a lower excretion of nitrogen/U flux.
Stack
T
T
Department of Child Health, University of Aberdeen, Rowett Research Institute, Scotland.
Reeds
P J
PJ
Preston
T
T
Hay
S
S
Lloyd
D J
DJ
Aggett
P J
PJ
D006801:Humans; D007223:Infant; D007225:Infant Food; D007227:Infant Nutritional Physiological Phenomena; D007230:Infant, Low Birth Weight / Q000378:metabolism*; D007231:Infant, Newborn; D008297:Male; D008895:Milk, Human; D009587:Nitrogen Isotopes; D014176:Protein Biosynthesis; D011492:Protein Hydrolysates; D011506:Proteins / Q000378:metabolism*
D009587:Nitrogen Isotopes; D011492:Protein Hydrolysates; D011506:Proteins