Objectives: To provide information on certain formulas that are relevant to allergy practice, focusing on their protein source and allergenicity, and to provide recommendations for selecting an optimal formula, taking into consideration efficacy, safety, palatability, and cost.
Data sources: A literature search using the PubMed database for the following keywords: hypoallergenic formulas, infant formulas, hydrolysate formulas, elemental formulas, and amino acids formulas.
Study selection: Information was derived from pertinent original studies and selected reviews, including recent Cochrane Database Systematic Reviews, published in the English-language literature.
Results: For a formula to be considered hypoallergenic, it should be well tolerated by at least 90% of individuals who are allergic to the parent protein from which that formula has been derived. Extensively hydrolyzed formulas (EHFs), derived from bovine casein or whey, are tolerated by approximately 95% of cow's milk allergic individuals. Elemental formulas are prepared from synthesized free amino acids and are well tolerated practically by all individuals, including those who are allergic to EHFs. Partially hydrolyzed whey formula (PHWFs) cause allergy in one-third to half of milk allergic individuals and are not considered hypoallergenic. Both EHFs and PHWFs seem to be equally effective in reducing the risk of development of allergy in infants of atopic families.
Conclusion: The EHFs and amino acids formulas, but not the partially hydrolyzed formulas, are optimal for milk allergic individuals. All 3 types of formulas are useful for prevention. The cost and palatability should be considered in deciding which formula to use.