Reviewing the medical records of 122 children with soy allergy, investigators found that less than half (45 percent) stopped having allergic reactions to soy products by age 6, while 69 percent did so by age 10. The findings call into question the common belief that most children outgrow soy allergy by the time they are in pre-school.

In the Johns Hopkins study, allergy persistence was directly linked to the levels of soy IgE antibodies in the blood — the higher the antibody count, the more persistent the reactions.

According to study investigator Robert Wood, M.D., most children who outgrew their allergy early experienced a peak in soy antibodies by age 3, with levels dropping thereafter. By contrast, children with persistent allergies had a slow, gradual increase in antibody levels, not peaking until around age 8.

Soy allergy affects 0.4 percent of U.S. children, making it half as common as peanut allergy, the researchers say. Many processed foods contain soy, and complete avoidance is difficult.

Co-investigators on the study include Jessica Savage, M.D.; Allison Kaeding, B.S.; and Elizabeth Matsui, M.D., M.H.S., all of Hopkins.

Founded in 1912 as the children's hospital of the Johns Hopkins Medical Institutions, the Johns Hopkins Children's Center offers one of the most comprehensive pediatric medical programs in the country, treating more than 90,000 children each year. Hopkins Children’s is consistently ranked among the top children's hospitals in the nation. Hopkins Children’s is Maryland's largest children’s hospital and the only state-designated Trauma Service and Burn Unit for pediatric patients. It has recognized Centers of Excellence in dozens of pediatric subspecialties, including allergy, cardiology, cystic fibrosis, gastroenterology, nephrology, neurology, neurosurgery, oncology, pulmonary, and transplant. For more information, please visit www.hopkinschildrens.org