Abstract
Cow's milk protein hydrolyzed formulas appeared in the 1940s with the aim of decreasing or eliminating the allergenicity of cow's milk proteins, in addition to reducing the risk of sensitization. In recent years, the so-called "hypoallergenic" formulas have been developed. The use of such hydrolyzed formulas is based on the premise that predigested proteins, when fed as amino acids and peptides, provide nutrients in a nonantigenic form. Thus, protein hydrolyzed formulas have been classified as hypoallergenic. These formulas are processed by heat and enzymatic hydrolysis, and the conformational and sequential structures are more or less changed. The formulas contain peptides of lower molecular weight than the native protein source, which are thought to be less immunogenic. Hydrolyzed formulas appear to be nutritionally adequate and infants generally gain weight until they refuse the formula because of its bad taste. However, caution should be taken when such formulas are given for prolonged periods since no data are available on nutritional assessment of infants exclusively fed hydrolyzed formulas for several months. In this paper we report and discuss more than 202 reactions to different hydrolyzed formulas, including cases of anaphylactic shock and apparent life-threatening events. The cross-reactivity between different hydrolyzed formulas and cow's milk proteins, and the potential immunogenicity of such formulas are discussed. We conclude that none of the hydrolyzed formulas are nonallergenic, both for allergic children and for high-risk babies. Moreover, we suggest that double-blind placebo-controlled food challenge studies in larger cohorts of babies evaluated with well-defined and well-validated diagnostic methods may establish a more reliable prevalence of allergy to hydrolyzed formulas.
