Children appear to be at less risk of developing peanut or tree nut (P/TN) allergies if their mothers are not allergic and ate more nuts during pregnancy, according to a study published by JAMA Pediatrics.
Previously, women had been advised to avoid highly allergenic foods such as P/TN 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 Based on the lack of evidence supporting early dietary avoidance, the AAP rescinded the recommendation in 2008.
A team of Boston researchers tested the hypothesis that women who eat nuts during pregnancy might bear children that would be desensitized and less likely to develop T/PN allergies. Study participants included children born to mothers who previously reported their diet during, or shortly before or after, their pregnancy as part of the ongoing Nurses’ Health Study II. Among 8205 children, researchers identified 308 cases of food allergy, including 140 cases of P/TN allergy.
Children of mothers who were not allergic to nuts and ate them at least 5 times per week had the lowest risk of P/TN allergy. This lower risk of P/TN allergy was not observed among the children of mothers who had a P/TN allergy.
THE BOTTOM LINE
The researchers found that the rate of peanut allergy was significantly lower among children in the study whose mothers ate peanuts during the early pregnancy period. While researchers do note that this is a significant finding, the data only demonstrates an association between maternal diet and the risk of peanut allergy in children. And note that the association does not hold among women who themselves have peanut allergies.
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. By linking maternal peanut consumption to reduced allergy risk, the researchers have provided new data to support the hypothesis that early allergen exposure increases tolerance and reduces risk of childhood food allergy, thereby lowering the risk of childhood food allergy.
While additional prospective studies are needed to replicate this finding, the data do appear to support the AAP decisions to rescind recommendations that all mothers avoid P/TN during pregnancy and breastfeeding—unless they have peanut allergies themselves.
- Frazier AL, Camargo CA, Malspeis S, Willett WC, Young MC. Prospective study of peripregnancy consumption of peanut or tree nuts by mothers and the risk of peanut or tree nut allergy in their offspring. JAMA Pediatr. 2013. Epub ahead of print. December 23, 2013. Abstract available at: http://archpedi.jamanetwork.com/article.aspx?articleid=1793699#Abstract. Accessed January 8, 2014.