Pediatric Nutrition in Practice

Protein 43

1

Amino Acid Requirement for Infants and
Children

The 9 indispensable amino acids (IAA; table  1 )
need to be obtained from the diet, and, therefore,
requirements have been defined for them. The
amino acid requirements (AI) for young infants
(0–6 months) are based on an average human
milk intake of 0.78 liters per day and the mean
content of each IAA in human milk ( table 3 ).
The EAR of IAA in older infants (7–12 months)
and children (1–18 years) are calculated using the
factorial method ( table 4 ). The method assumes
that the maintenance requirement of each IAA is
similar to that of adults and the requirements dif-
fer in children only by their growth needs. The
requirement for growth is estimated from the
rate of protein deposition, the amino acid com-
position of whole-body protein and the efficiency
of protein utilization.
Recently, it was shown that the maintenance
requirements for adults and children are similar
[6 –8]. For a detailed review on the methods to
determine amino acid requirements, refer to
Pencharz and Ball [9]. Of late, neonatal amino
acid requirements became available for some es-
sential amino acids [10 , 11].
The conditionally IAA ( table 1 ) are those that
the infant or child is unable to produce in suffi-

cient amounts and, hence, all or part of the daily

needs for that amino acid must be provided by

the diet.

P r o t e i n Q u a l i t y

The requirement of protein is affected not only by

the quantity but also by the quality of the protein

source. Different sources of protein vary widely in

their chemical composition and nutritional value.

Ta b l e 2. Protein requirement for infants, children and adolescents

Age Average requirement

(EAR)a, g protein/kg body

weigh t per day

Safe level of intake

(RDA)b, g protein/kg body

weight per day

Intake

per day, g

7 – 12 months 1.0 1.2 11

1 – 3 years 0.87 1.05 13

4 – 8 years 0.76 0.95 19

9 – 13 years 0.76 0.95 34

14 – 18 years (boys) 0.73 0.85 52

14 – 18 years (girls) 0.71 0.85 46

Data from Dietary Reference Intakes 2002/2005 [3]. a Calculated from maintenance + growth (rate

of protein deposition × efficiency of protein utilization). b Calculated from EAR + 2 × SD of EAR.

Ta b l e 3. IAA requirements for young infants 0 – 6 months

of age

IAA AIa, mg/kg

per day

Intake

per day, mg

Histidine 36 214

Isoleucine 88 529

Leucine 156 938

Lysine 107 640

Methionine + cysteine 59 353

Phenylalanine + tyrosine 135 807

Threonine 73 436

Tryptophan 28 167

Valine 87 519

Data from Dietary Reference Intakes 2002/2005 [3]. a Cal-

culated from the average volume of human milk intake

and the mean IAA content of human milk.

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