If an infant has an allergy to cow’s milk, why should a parent go for dairy based formulas (hydrolysates) and not for soy or rice products? This seems to be counterintuitive.

Cow’s milk is an ideal basis for the development of infant formulas. The amino acid composition of the proteins in milk is very near to the amino acid needs of the infant, much closer than the amino acid composition of soy or wheat protein. Therefore, the nutritional quality of cow’s milk is very high in comparison to vegetable proteins.

The nutritional quality of the proteins in food depends in the first place on their content of indispensible amino acids. The ideal food protein would be the protein that contains essential amino acids in exactly the same ratio as the proteins that are produced in the human body. Since this is not the case for any known food protein, each food protein has a characteristic which limits its nutritional value. This value is determined by the level of the indispensible amino acid that, relative to the body protein to be produced, is contained in the food protein in the smallest quantity. Cereal proteins may be rich in other amino acids, but their nutritional quality is limited by the lysine content. Milk proteins, on the other hand, are rich in all essential amino acids, so milk protein has a very high nutritional quality.