Pediatric Nutrition in Practice

Protein 45

1

The protein quality is principally determined by
digestibility and the amino acid composition of
the protein. The more important factor of the two
is the relative content and metabolic availability
of the individual IAA.
If the content of a single IAA in the diet is less
than the individual’s requirements, then it will
limit the utilization of other amino acids and
thus prevent normal rates of protein synthesis
even when the total nitrogen intake is adequate.
Thus, the ‘limiting amino acid’ will determine
the nutritional value of the total nitrogen or pro-
tein in the diet.

P r o t e i n S o u r c e s

Protein from animal sources such as meat, poul-
try, fish, eggs, milk, cheese and yogurt provide all
9 IAA and are called ‘high-quality’ or ‘complete
proteins’. Protein from plants, legumes, grains,
nuts, seeds and vegetables tend to be deficient in
one or more of the IAA and are called ‘incomplete
proteins’. Specifically, cereal grains are deficient
in lysine and legumes are deficient in methionine.

Thus, for children who are actively growing, it is

recommended to ensure sufficient intake of ‘high-

quality’ protein. Children who restrict their diet to

plant proteins should consume a varied diet con-

taining complementary mixtures of protein (e.g.

rice with beans) to ensure adequate protein intake.

Conclusions

• For infants 0–6 months of age, human milk is
  considered the ideal food and the protein in-
  take to be sufficient to maintain growth and to
  meet other needs


• The protein requirement for children is affect-
  ed by both the quantity and quality of the pro-
  tein source


• All IAA requirements must be met by the diet
  to ensure normal rates of protein synthesis in
  healthy children


• Therefore, consumption of ‘high-quality’ pro-
  tein rich in the 9 IAA, principally animal
  sources such as meat, poultry, eggs, milk
  products and complementary mixtures of
  plant protein, is recommended

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9 Pencharz PB, Ball RO: Different ap-

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23: 101–116.

10 de Groof F, Huang L, van Vliet I, Voort-

man GJ, Schierbeek H, Roksnoer LC,

Vermes A, Chen C, Huang Y, van Goud-

oever JB: Branched-chain amino acid

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nates in the first month of life. Am J Clin

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11 Huang L, Hogewind-Schoonenboom JE,

van Dongen MJ, de Groof F, Voortman

GJ, Schierbeek H, Twisk JW, Vermes A,

Chen C, Huang Y, van Goudoever JB:

Methionine requirement of the enterally

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References

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Koletzko B, et al. (eds): Pediatric Nutrition in Practice. World Rev Nutr Diet. Basel, Karger, 2015, vol 113, pp 41–45
DOI: 10.1159/000367868