Children appear to be less at risk for 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, a JAMA Network publication.

In the United States, the prevalence of childhood peanut allergy has more than tripled from 0.4 percent in 1997 to 1.4 percent in 2010. The onset of these allergies is usually in childhood and most often occurs with the first known exposure. Peanut or tree nut allergies typically overlap, according to the study background.

A. Lindsay Frazier, M.D., Sc.M., of the Dana-Farber Children's Cancer Center, Boston, and colleagues examined the association between pregnant mothers eating peanuts or tree nuts and the risk of P/TN allergies in their children.

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 8,205 children, researchers identified 308 cases of food allergy, including 140 cases of P/TN allergy.

Study findings indicate that children whose nonallergic mothers had the highest P/TN consumption (five times a week or more) 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.

"Our study supports the hypothesis that early allergen exposure increases the likelihood of tolerance and thereby lowers the risk of childhood food allergy. Additional prospective studies are needed to replicate this finding," the study concludes. "In the meantime, our data support the recent decisions to rescind recommendations that all mothers avoid P/TN during pregnancy and breastfeeding."

(JAMA Pediatr. Published online December 23, 2013. doi:10.1001/jamapediatrics.2013.4139. Available pre-embargo to the media at http://media. jamanetwork. com .)

Editor's Note: An author disclosed book royalties. This work was supported by Food Allergy Research and Education, New York. Please see the articles for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

Editorial: What Foods Are Safe to Consume During Pregnancy

In a related editorial, Ruchi Gupta, M.D., M.P.H., of the Northwestern University Feinberg School of Medicine, Chicago, writes: "Frazier and colleagues report a strong inverse association between peripregnancy nut intake and the risk of nut allergy in children among mothers who did not have nut allergies."

"Although the dietary surveys were not specific for the actual dates of pregnancy, these findings support recent recommendations that woman should not restrict their diets during pregnancy. Certainly, women who are allergic to nuts should continue avoiding nuts," Gupta continues.

"For now, though, guidelines stand: pregnant women should not eliminate nuts from their diet as peanuts are a good source of protein and also provide folic acid, which could potentially prevent both neural tube defects and nut sensitization. So, to provide guidance in how to respond to the age-old question "To eat or not to eat?" mothers-to-be should feel free to curb their cravings with a dollop of peanut butter!"

(JAMA Pediatr. Published online December 23, 2013. doi:10.1001/jamapediatrics.2013.4602. Available pre-embargo to the media at http://media. jamanetwork. com .)

Editor's Note: Please see the articles for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

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Media Advisory: To contact corresponding author Michael C. Young, M.D., call Meghan Weber at 617-919-3656 or email meghan.weber@childrens.harvard.edu. To contact editorial author Ruchi Gupta, M.D., M.P.H., call Marla Paul at 312-503-8928 or email marla-paul@northwestern.edu, or email r-gupta@northwestern.edu.