LOS ANGELES — Pregnant peanut lovers can celebrate, perhaps with a PB&J snack: A study out Monday shows an association between pregnant women who ate the most peanuts and tree nuts and children with a decreased risk of allergy.
Women had been advised to avoid peanuts and tree nuts, as well as other highly allergic foods, during pregnancy and until the child turned 3, as a way to try to reduce the chances of an allergy. But those recommendations were rescinded after researchers found that the effort didn’t work.
In the current study — from Boston Children’s Hospital and published Monday in the Journal of the American Medical Association Pediatrics — found that women who ate nuts more than five times a month had the lowest incidence of allergic children.
“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,” Dr. Michael Young, lead author of the study, said in a statement.
“Current guidelines recommend that mothers should not restrict their diets during pregnancy, but this recommendation remains a widely debated topic among food allergy experts,” Dr. Ruchi Gupta wrote in an opinion piece accompanying the study. Further research is needed, Gupta wrote, to determine why one in 13 U.S. children has a food allergy of some kind.
Despite recommendations to avoid allergens, more children were found to be allergic to nuts and other foods, with the rate tripling from 1997 to 2007. Peanut allergies affect 1 percent to 3 percent of people in most Western countries. In the U.S., it’s at 4 percent, the study said. The reasons are not known.
“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 said.
The researchers looked at data from 8,205 children, whose parents were part of the Nurses Study, a long-term health study. They found 140 cases of peanut or tree nut allergy among the children born between Jan. 1, 1990, and Dec. 31, 1994.
Animal studies have shown a protective effect of maternal exposure to allergens in foods. The human data, Young said, are not strong enough to conclude a cause and effect relationship. He said more research is needed.
Tree nuts are walnuts, almonds, pistachios, cashews, pecans, hazelnuts, macadamia nuts and Brazil nuts. Peanuts, Gupta noted, are a good source of protein, and they provide folic acid, which has the potential to prevent neural tube defects.
Of course, the researchers said, women who are themselves allergic should not eat peanuts or tree nuts.