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FOOD AND METABOLISM IN INFANCY The relationships of plasma amino acids as an indicator of the adequacy of protein intake
Author(s) -
HEIRD WILLIAM C.,
B.DELL RALPH,
WINTERS ROBERT W.
Publication year - 1982
Publication title -
acta pædiatrica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 115
eISSN - 1651-2227
pISSN - 0803-5253
DOI - 10.1111/j.1651-2227.1982.tb09623.x
Subject(s) - medicine , postprandial , amino acid , metabolism , endocrinology , physiology , biochemistry , biology , insulin
Heird, W. C., Dell, R. B. and Winters, R. W. (Department of Pediatrics and Institute of Human Nutrition, Columbia University College of Physicians & Surgeons, New York). Food and metabolism in infancy. Acta Paediatr Scand, Suppl. 299: 24, 1982.—Published plasma amino acid data from normally‐growing term and preterm infants fed varying quantities of protein as well as proteins of varying quality were examined in an effort to assess the efficacy of these data as indicators of the adequacy and/or inadequacy of protein intake. Although the absolute plasma concentrations of most amino acids vary considerably, all sets of data from term infants, with exception of those from infants fed inadequate protein or inordinately large quantities of protein, when expressed as the ratio of TEAA/TAA and ind. EAA/TEAA, are remarkably similar. Despite variations in absolute plasma amino acid concentrations of as much as 60 %, for example, fasting and postprandial TEAA/TAA and ind. EAA/TEAA ratios are similar. The plasma TEAA/TAA ratio of infants fed a low protein intake (1.1 g/kgd) is low but this ratio is similar in plasma of infants fed either 3.0‐3.5 g/kgd or 9 g/kgd. Ind. EAA/TEAA ratios, on the other hand, are the same in plasma of infants fed either 1.1 or 3.0‐3.5 g/k ‐ d but some are dramatically higher in plasma of infants fed a protein intake of 9.0 g/kgd. Although ind. EAA/TEAA ratios vary somewhat as a function of the quality of protein intake, this variation is not nearly as great as that of the intake ratios. Finally, the relatively constant plasma ratios of TEAA/TAA and ind. EAA/TEAA are remarkably similar to those of the tissue deposited during normal growth. These observations support the hypothesis that the various enteric, hepatic and other mechanisms which determine the amino acid composition of plasma have as their target these relationships among various amino acids rather than absolute plasma concentrations of the various amino acids. If so, it follows that maintenance of these relationships may be an important factor for optimal protein synthesis. If these hypotheses prove to be correct, an appropriate criteria for efficacy of alternative feeding regimens chosen for the infant who is not or cannot be breast fed is whether or not this regimen overwhelms the mechanisms responsible for maintaining these apparent relationships among the amino acids in plasma.