Delaying the introduction of highly allergenic foods - other than milk - does not seem to be effective in preventing food allergies, according to research presented here Tuesday during the 61st annual meeting of the American Academy of Allergy Asthma and Immunology.

“It is probably not useful for children in families at high risk for [allergies] to delay the introduction of these foods.” However, additional studies are needed before definite conclusions and recommendations can be made, Dr. Berber J. Vlieg-Boerstra, who presented his team’s work, told AMN Health.

“The delayed introduction of highly allergenic foods is often recommended for the primary prevention of food allergy in high risk infants,” the researcher, based at University Hospital Groningen in the Netherlands, pointed out.

“For example, the American Academy of Pediatrics recommends postponing the introduction of egg, fish, tree nut and peanuts until after the age of two or three.” But the efficacy of this approach is poorly documented.

To investigate, Vlieg-Boerstra and colleagues studied 41 children who were an average of six years old who had egg, soy, peanut and hazelnut eliminated from their diet from birth in an attempt to prevent the development of allergy to these foods.

The investigators used food challenge tests to determine the rate of clinical reactivity to the eliminated foods. The study included a placebo (control) group of 49 age-matched children with suspected food allergy who had not avoided these foods.

“We found no clinical differences in the number of positive [food challenge tests] or in the threshold dose between cases and controls,” Vlieg-Boerstra said. “As many children in the primary prevention group as in the control group showed food allergic reactions to these foods and the amount of allergenic food the children reacted to was similar in both groups.”

Further analysis showed that a higher RAST score (specific IgE) or skin prick test increased the relative risk of a positive food challenge test, by 30 percent and six percent, respectively, while gender, family history of allergy or sensitization and dietary avoidance did not.

Vlieg-Boerstra cautioned, however, that a significant number of children - 39 percent in this study - may have allergic reactions following their first known exposure to allergenic foods.

“Sensitized children are at greater risk, so we recommend that sensitized children should have their first exposure to these foods under medical supervision,” he said.

He added that he was not really surprised by the results, noting that “sensitization to foods can take place prior to birth or during breast feeding - and another recently completed study from our center shows that complete avoidance does not seem feasible for most patients.”