ALLERGY TO SOY FORMULA AND TO EXTENSIVELY HYDROLYZED WHEY FORMULA IN INFANTS WITH COW’S MILK ALLERGY: A PROSPECTIVE, RANDOMIZED STUDY WITH A FOLLOW-UP TO THE AGE OF 2 YEARS
Klemola T, Vanto T, Juntunen-Backman K, Kalimo K, Korpela R, Varjonen E. J Pediatr. 2002;140:219–224
Purpose of Study.
To evaluate the cumulative incidence up to the age of 2 years of allergy or other adverse reactions to soy formula and to extensively hydrolyzed formula in infants with confirmed cow’s milk allergy.
The study group was comprised of 170 children with cow’s milk allergy (99 boys and 71 girls) with a mean age at the time of diagnosis of 7 months (range: 2–11 months). All the patients had their diagnosis confirmed by double-blind, placebo-controlled challenge (DBPCFC) except for 4 patients with a history of an anaphylactic reaction to cow’s milk and positive immunoglobulin (IgE) antibodies to this protein.
Infants with documented cow’s milk allergy were randomly assigned to receive either a soy formula (Soija Tutteli, Valio Ltd, Valio, Finland) or an extensively hydrolyzed formula (Peptidi Tutteli, Valio Ltd, Valio, Finland). If there was a clinical suspicion that the formula caused symptoms, a DBPCFC with the formula was performed. The children were followed to the age of 2 years, and soy-specific IgE antibodies were measured at the time of diagnosis and at ages 1 and 2 years.
An adverse reaction to the formula was confirmed by challenge in 8 patients (10%; 95% confidence interval: 4.4%–18.8%) randomly assigned to soy formula and in 2 patients (2.2%; 95% confidence interval: 0.3%–7.8%) randomly assigned to extensively hydrolyzed formula. Adverse reactions to soy were similar in IgE-associated and non-IgE-associated cow’s milk allergy (11% and 9%, respectively). IgE to soy was detected in only 2 infants with an adverse reaction to soy. Adverse reactions to soy formula were more common in younger (<6 months) than in older (6–12 months) infants (5 of 20 vs 3 of 60, respectively; P = .01).
Soy formula was well-tolerated by most infants with IgE associated and non-IgE-associated cow’s milk allergy. Development of IgE-associated allergy to soy was rare. Soy formula can be recommended as a first-choice alternative for infants ≥6 months of age with cow’s milk allergy.
This is a very useful clinical investigation with practical applications. The study data demonstrate that only 10% of infants with cow’s milk allergy have any kind of adverse reaction after the ingestion of soy formula. Moreover, severe allergic reactions or development of IgE-mediated allergy to soy was found to be very uncommon in infants with cow’s milk allergy. This investigation is a nice corollary to a previous publication by Zeiger et al (J Pediatr. 1999;134:614–622.) that found the prevalence of soy allergy in children with IgE-mediated cow’s milk allergy to be 14%. Cow’s milk allergy affects approximately 2.5% of infants with possible alternative including soy formula, extensively hydrolyzed protein formulas, or amino acid formulas. Of these choices, soy formulas provide the most affordable and palatable choice while meeting the nutritional needs of these infants.