Can Eating More Allergens During Pregnancy Prevent Food Allergies? Major Trial Says No

Increasing maternal consumption of eggs and peanuts during pregnancy and breastfeeding did not significantly reduce a child’s risk of developing allergies to those foods, according to results from the PrEggNut randomized clinical trial published in the New England Journal of Medicine. Led by Debra J Palmer, PhD, of the University of Western Australia, the study evaluated whether dietary intervention in mothers could protect infants with a strong family history of allergic disease from developing food allergies.

The multicenter trial enrolled 2,137 pregnant women across four Australian cities who had singleton pregnancies at less than 23 weeks’ gestation and planned to breastfeed for at least four months. Although the participating mothers had no history of egg or peanut allergy, each fetus had a strong family history of allergic conditions, defined as at least two biological family members diagnosed with asthma, eczema, allergic rhinitis, or food allergy. Participants were randomized to either a high-intake regimen—consuming at least six eggs and 60 peanuts weekly—or a standard diet with no more than three eggs and 30 peanuts weekly. The intervention continued through four months postpartum during lactation.

At 1 year of age, the proportion of infants with immunoglobulin E (IgE)-mediated egg or peanut allergy showed no significant difference between the two groups. In the intention-to-treat analysis, 7.8% of infants in the high-intake group developed an allergy compared with 8.4% in the standard-diet group. Secondary endpoints showed comparable outcomes for individual egg and peanut allergies, as well as infant eczema rates at 4 and 12 months.

“There were also no indications that higher maternal egg and peanut ingestion reduced (or increased) the risk of infant egg or peanut sensitization, IgE-mediated egg allergy, IgE-mediated peanut allergy, or medical diagnosis of eczema,” Palmer and colleagues reported. Consequently, the team noted that “this finding reinforces the importance of timely introduction of egg and peanut in infant diets.”

In an accompanying editorial, Maria C Jenmalm, PhD, of Linköping University in Sweden, reflected on prior breakthroughs demonstrating that early oral exposure in infants can promote tolerance, noting that researchers wanted to examine “whether the window for prevention begins even earlier, during fetal life and breast-feeding, when the developing immune system is first exposed to maternal antigens and dietary proteins.”

Despite the neutral findings, Jenmalm stressed that the trial provides reassuring guidance for prospective parents. “Pregnant and lactating women who tolerate egg and peanut need not avoid these foods for allergy prevention. Equally, they should not feel obliged to consume high quantities of egg or peanut to protect their child. This message is especially important for families with strong allergic histories, who may already have anxiety about infant allergy risk,” Jenmalm explained.

Ultimately, the findings support focusing food allergy prevention efforts on well-established infant-feeding guidance rather than prescribing high maternal intake of egg and peanut during pregnancy and breastfeeding. As Jenmalm concluded, “The trial supports counseling that is permissive rather than prescriptive: maintain a nutritionally adequate, varied diet according to preference and tolerance, and focus prevention advice on timely introduction and ongoing inclusion of allergenic foods in the infant diet when developmentally appropriate.” The researchers cautioned that the findings apply to infants with a strong family history of allergic disease and assessed food allergy outcomes at 1 year of age.