Protein is most essential for growth and is the basic building material for the body’s tissues. Infants require the following amino acids for their growth.
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
Of these, histidine is essential only for infants. Some amino acids are conditionally essential, that is essential for the infant only under certain conditions like illness, prematurity or inborn errors of metabolism. These include-
Cysteine
Tyrosine
Taurine
The quality of protein is as important as the quantity. A good quality protein in adequate quantity supplies all the essential amino acids in sufficient amounts for growth and maintenance. The protein RDA for infants is based on the protein content of breast milk consumed by infants growing adequately. It is given as 2 gm/kg body weight of infants in the 0-6 months age and 1.65 g/kg for infants in the 6 months to 12 month age group. These protein recommendations are given for healthy, full term infants. Infection, premature birth, illness and genetic disorders all increase protein needs. If energy intake is inadequate, protein is used for energy and this increases protein requirement.
Excess dietary protein can also cause problems especially for a small infant. Excess protein in the blood stresses the kidneys and liver as these organs metabolize and excrete the excess nitrogen. Signs of protein overload include acidosis, dehydration, diarrhea, elevated blood urea and ammonia and fever. This type of problem is observed in infants fed inappropriate foods such as non fat milk or concentrated formula.
