The Essential Amino Acid Requirements of Infants: Lysine

Snyderman, Selma E.; Norton, Patricia M.; Fowler, Dorothy I.; Holt, L. Emmett; Hasselmeyer, Eileen G.; Boyer, Audrey

doi:10.1001/archpedi.1959.02070010177004

Cited by 14 publications

(8 citation statements)

References 9 publications

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“…Their known rapidity of absorption from the gastrointestinal tract [1] and their relatively low hepatic metabolism [7] may explain this in part. More difficult to explain is the sharp decrease in lysine when subjects are on low protein diets and elevation of this amino acid when they are on a high protein diet; that a limiting value has been reached in the former case is not compatible with data on the infant's lysine requirement [11]. It is also difficult to explain the discrepancy between the more marked drop in the levels of lysine in plasma on the low milk diet as contrasted with its failure to fall strikingly in the mild cases of Kwashiorkor [5].…”

Section: Discussionmentioning

confidence: 93%

The Plasma Aminogram. I. Influence of the Level of Protein Intake and a Comparison of Whole Protein and Amino Acid Diets

et al. 1968

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ExtractThe changes in plasma aminogram prcduced by variations in level of protein intake provided either as whole protein or a mixture of amino acids were studied. Controls were 29 normal infants, one to three months of age, fed a standard evaporated milk formula providing 3 to 3.5 g/kg/day of protein (fig. 1 and table II). Results obtained with the lowest protein intake (1.1 g/kg/day) are illustrated in figure 2 and presented in table III. Alterations in the plasma aminogram are noted as early as two days after the reduction in intake and become more pronounced as the feeding is prolonged. The most striking changes are depression of the branched chain amino acids (leucine, isoleucine and valine) and of lysine and tyrosine. Glycine and serine are elevated with glycine showing the greater elevation. Less striking changes are decreased concentrations of threonine, phenylalanine, ornithine, butyrine, cystine and proline.The aminograms obtained with feedings of 1.3 and 1.5 g/kg/day are very similar to those obtained with the more extreme degree of protein reduction ( fig. 3 and table IV). The aminogram after feeding 1.7 g/kg/day remains within the range of average ±1 standard deviation except for the elevation of glycine.A high intake of milk protein, 9 g/kg/day, results in an increase in the levels of a majority of the amino acids ( fig. 5 and table V). The sole exception is glycine, which tends to be low. Marked increases occur in the branched chain amino acids, valine being the most affected; there is also a large increase in the level of proline. The greatest elevations occur in the levels of methionine, which also show the most marked individual variation, elevations ranging from 2 to 35 times normal average value. An apparent tendency of the methionine level to return towards normal with prolonged feeding of the high protein diet is evident on the graph. The significance of this finding must be questioned, however, since the subjects who were maintained the longest on this diet were those who originally did not have the very high levels of methionine.There are some differences in the aminogram when infants are fed the equivalent of 3.5 g/kg/day in the form of amino acids instead of intact protein ( fig. 6 and table VI). On the amino acid diets, lower average plasma values are seen for the branched chain amino acids, alanine, proline, asparagine and citrulline; higher values are observed for threonine and serine. The markedly elevated levels of plasma amino acid observed after feeding 9 g/kg/day of whole protein are not seen after feeding the equivalent amount of nitrogen as an amino acid mixture ( fig. 7 and table VII). There is elevation only of valine and serine. When individual subjects were shifted from the high protein to the high amino acid diet, the pattern shifted within 24 hours. SNYDERMAN, HOLT, NORTON, ROITMAN, PHANSALKAR SpeculationA more precise and sensitive indicator of the state of protein nutrition is needed. While the level of the plasma amino acids changes rapidly with alterations in protein...

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Section: Discussionmentioning

confidence: 93%

The Plasma Aminogram. I. Influence of the Level of Protein Intake and a Comparison of Whole Protein and Amino Acid Diets

et al. 1968

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“…Lysine is the first limiting amino acid in the all cereal-based diet consumed by a large proportion of the world's population (3). A deficiency in the intake of lysine limits protein synthesis and causes weight loss in infants (4). In contrast, excess lysine intake also reduces the growth rate of animals caused by an imbalanced diet (5,6).…”

Section: Introductionmentioning

confidence: 99%

“…Only a few studies have been performed in infants to determine enteral lysine requirements (4,7). The criteria for the adequacy of a diet were the nitrogen balance and growth rates, which may not be the most sensitive methods.…”

Section: Introductionmentioning

confidence: 99%

Lysine requirement of the enterally fed term infant in the first month of life

Huang¹,

Hogewind-Schoonenboom²,

Groof³

et al. 2011

The American Journal of Clinical Nutrition

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Background: Infant nutrition has a major impact on child growth and functional development. Low and high intakes of protein or amino acids could have a detrimental effect. Objective: The objective of the study was to determine the lysine requirement of enterally fed term neonates by using the indicator amino acid oxidation (IAAO) method. L-[1-13 C]phenylalanine was used as an indicator amino acid. Design: Twenty-one neonates were randomly assigned to lysine intakes that ranged from 15 to 240 mg Á kg 21 Á d 21 . Breath, urine, and blood samples were collected at baseline and during the plateau. The mean lysine requirement was determined by using biphasic linear regression crossover analysis on the fraction of 13 CO 2 recovery from L-[1-13 C]phenylalanine oxidation (F 13 CO 2 ) and phenylalanine oxidation rates calculated from the L-[1-13 C]phenylalanine enrichment of urine and plasma. Results: The mean (6SD) phenylalanine flux calculated from urine and plasma L-[1-13 C]phenylalanine enrichment data were 88.3 6 6.9 and 84.5 6 7.4 lmol Á kg 21 Á h 21 , respectively. Graded intakes of lysine had no effect on phenylalanine fluxes. mean requirement was identical to the requirement determined by using phenylalanine oxidation rates in urine and plasma. Conclusions: The mean lysine requirement of enterally fed term neonates was determined by using F 13 CO 2 and phenylalanine oxidation rates calculated from the L-[1-13 C]phenylalanine enrichment of urine and plasma. These methods yielded a similar result of 130 mg lysine Á kg 21 Á d 21 . This study demonstrates that sampling of 13 CO 2 in expired air is sufficient to estimate the lysine requirement by using the IAAO method in infants. This trial was registered at www.trialregister.nl as NTR1610.

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“…A lysine loading test in the parents gave normal results ( tein intake of 3.0 mg/kg/day.5 They used a mixture of L-amino acids simulating the composition of breast milk protein. 6 Lysine as an essential amino acid is often added to infant food such as powdered milk and flour preparations. This renders the com¬ position of a lysine-poor diet more difficult.…”

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confidence: 99%