Background: Hydrolysates are used in the treatment and prevention of cows milk protein allergy. Hydrolysis might alter the plasma level of amino acids.
Methods: Forty-five infants were included in a double-blind prospective study and were randomized in two groups: one receiving a whey predominant formula (n = 20) and the second group receiving a whey hydrolysate formula (n = 25). Weight and length gain was evaluated up to the age of 13 weeks, when blood was sampled for determination of fasting plasma amino acids.
Results: Four infants of the hydrolysate group dropped out because refusal to ingest the formula. Weight and length gain at 13 weeks of age were extremely comparable. Significant differences in plasma concentrations were observed for a number of nonessential and essential amino acids (p = .035 to .0001). Threonine and lysine were both higher in the hydrolysate group, and aspartic acid, cystine, methionine, tyrosine, phenylalanine, histidine, and arginine were lower in the hydrolysate group.
Conclusions: These differences in plasma amino acid levels have to be regarded with care because all concentrations were within normal ranges, with the exception of threonine. Weight and length gain of the hydrolysate and the whey predominant formula were identical.