Study: Nuts in pregnancy do not raise allergy risk

A new study gives reassurance that women who eat nuts or peanut butter during pregnancy are not raising the risk that their children will have nut allergies. Kids whose moms ate nuts most often were actually less likely to have problems consuming them, researchers found.

Peanut allergies are on the rise and affect up to 2 percent of the population in the United States and other Western countries. Women were once advised to avoid nuts in pregnancy to avoid triggering allergies in their offspring, but that advice was later rescinded. Studies went back and forth, and some even suggested that avoiding nuts during pregnancy increased a child’s chances of being allergic to them.

The new research supports that theory. It involves more than 8,000 children born to female nurses in a long-running U.S. study that periodically asked questions about diet and health habits.

Doctors and tests confirmed that 140 children had allergies to peanuts or tree nuts such as walnuts, almonds or pecans. Fifty-eight had mothers who were allergic to nuts, and 82 did not. Looking at this second group, researchers found that children whose moms ate nuts at least five times a month were 69 percent less likely to have nut allergies than those whose moms rarely ate nuts.

“Our study adds to the evidence that early exposure to allergens might be a way that you induce tolerance,” but is not the kind of research that can prove cause and effect, said Dr. Michael Young, a pediatrician at Harvard Medical School and Children’s Hospital Boston.

He led the study, published Monday in JAMA Pediatrics.

A big caveat: Researchers had no information on fathers’ nut allergies, which could pass to a child. Allergies can be inherited, “but the maternal component seems to be more relevant” than the father’s genes, Young said.

In any case, the results support the advice that women should not restrict their diets in pregnancy unless they are allergic to nuts, Dr. Ruchi Gupta of Northwestern University wrote in a commentary in the journal.

Peanuts are a good source of protein and folic acid, which helps prevent certain birth defects, Gupta noted. “Mothers-to-be should feel free to curb their cravings with a dollop of peanut butter!”

The Food Allergy Research and Education, a New York-based nonprofit group that advocates for people with allergies and gets some funding from industry sources, sponsored the work but had no role in designing or running the study.