With the spike in childhood food allergies over the past generation, doctors once believed that the best way to reverse the trend was to keep babies away from highly allergenic foods like nuts—both in the womb and during the first few years of life. Some pregnant women were told to avoid eating peanuts and tree nuts, even if they, themselves, weren’t allergic.
But that appears to have been bad advice. Researchers from Boston Children’s Hospital found that children born to women who ate peanuts, almonds, or other nuts on a near daily basis during pregnancy were about 30 percent less likely to develop peanut or tree nut allergies compared to those born to women who rarely ate nuts.
Neither of the two groups of women had nut allergies themselves, though the researchers also looked at pregnant women who did. They found that for children born to mothers with nut allergies who ate nuts they weren’t allergic to, they had a slight but non-significant increase in allergies. This is compared to those pregnant mothers with allergies who avoided nuts altogether, according to the study published Monday in JAMA Pediatrics.
“We can’t make a recommendation based on our findings that women should eat nuts during pregnancy to protect against allergies in their newborns,” said study co-author Dr. Michael Young, an allergy and immunology specialist at Boston Children’s. “But we can say that pregnant women should no longer be fearful of eating nuts and should eat them if desired.”
The Boston researchers conducted the study by examining health surveys filled out by 8200 children born to women who years earlier had participated in the landmark Nurses’ Health study where they regularly completed dietary surveys, sometimes during pregnancy. The researchers tried to take into account other differences between the nut eaters and nut avoiders that might have also protected children from allergies—such as a higher fruit and vegetable intake during pregnancy among the nut eaters.
But other differences might have also existed, so the study couldn’t prove that eating nuts provided the allergy protection.
“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,” wrote Dr. Ruchi Gupta, a food allergy researcher at the Northwestern University Feinberg School of Medicine in an editorial that accompanied the study.
Other recent studies also suggests that toddlers might benefit from eating allergenic foods—such as fish, nuts, and eggs—to help lower their likelihood of allergies later on. A 2008 British study found that Israeli babies whose early diets included a soft peanut-based snack were 10 times less likely to develop food allergies in elementary school than their counterparts raised in Britain, who weren’t exposed to peanuts as babies. Based on this and other research, the American Academy of Pediatrics no longer recommends that toddlers avoid such foods for the first few years of life.