Peanut and tree nut allergy incidence lower among children whose mothers ate them during pregnancy, study finds

"Our study showed increased peanut consumption by pregnant mothers who weren't nut allergic was associated with lower risk of peanut allergy in their offspring," says the study's senior author Michael Young, MD, of Boston Children's Division of Allergy and Immunology. "Assuming she isn't allergic to peanuts, there's no reason for a woman to avoid peanuts during pregnancy."

Previously, women had been advised to avoid highly allergenic foods such as peanuts and tree nuts during pregnancy and while nursing, and that their children should avoid peanuts until 3 years of age. The goal of these recommendations, despite a lack of supporting research, was to minimize early allergen exposure and sensitization, thereby reducing the risk of developing childhood peanut allergy. The American Academy of Pediatrics (AAP) endorsed these recommendations in 2000. However, from 1997 to 2007, the number of peanut allergy cases in the U.S. tripled, leading the medical community to reexamine its recommendations. Based on the lack of evidence supporting early dietary avoidance, the AAP rescinded the recommendation in 2008.

"No one can say for sure if the avoidance recommendation for peanuts was related to the rising number of peanut allergies seen in the late 1990s and early 2000s, but one thing is certain: it did not stop the increase," Young says. "It was clear that a new approach was needed, opening the door for new research."

To further define the relationship between maternal diet and the development of food allergy in offspring, Young and his team analyzed large amounts of data provided by the Growing Up Today Study (GUTS). Examining the records of 8,205 children, the researchers positively identified 140 cases of peanut or tree nut allergies. They then examined the diets of each child's mother -- specifically, peanut and nut consumption -- during the peri-pregnancy period and compared them with the dietary habits of pregnant women whose children did not develop a peanut allergy.

Young and team found that the rate of peanut allergy was significantly lower among children in the study whose mothers ate peanuts during the peri-pregnancy period. Although this is a substantial finding, the data demonstrate only an association between maternal diet and the risk of peanut allergy in children.

"The data are not strong enough to prove a cause-and-effect relationship. Therefore, we can't say with certainty that eating more peanuts during pregnancy will prevent peanut allergy in children. But we can say that peanut consumption during pregnancy doesn't cause peanut allergy in children," Young says. "By linking maternal peanut consumption to reduced allergy risk we are providing new data to support the hypothesis that early allergen exposure increases tolerance and reduces risk of childhood food allergy."