It doesn’t look like it, at least not for peanuts and eggs, according to this study.
An Australian study has found that eating lots of eggs and peanuts in pregnancy doesn’t seem to affect whether the child subsequently develops allergies to those foods.
The final analysis in the randomised controlled PrEggNut Study included 2137 pregnant women whose unborn children had at least two biological family members with medically diagnosed allergies (asthma, eczema or atopic dermatitis, allergic rhinitis, or IgE-mediated food allergy). The participants could not have peanut or egg allergies as they would not be able to follow the protocol.
Around half of the pregnant women (1070) followed a diet rich in eggs and peanuts, eating at least six eggs and 60 peanuts every week, and the rest (1067) ate a standard diet with no more than three eggs and 30 peanuts a week.
The participants were meant to follow their allocated diet from their entrance into the study, before 23 weeks pregnancy, to four months after the birth, while the children were being breastfed.
Researchers then tested the children for IgE-mediated egg or peanut allergy at one year of age. There were 83 kids with an egg or peanut allergy in the high egg-peanut group (7.8%), and 89 (8.4%) in the standard diet group.
As a strategy to avoid egg and peanut allergies in young children, this did not appear to work.
“In this large trial, higher maternal dietary intake of eggs and peanuts during pregnancy and lactation did not reduce (or increase) the risk of infant IgE-mediated egg or peanut allergy,” the researchers concluded in the New England Journal of Medicine.
One finding of interest was that the prevalence of IgE-mediated allergy in the study was lower than the anticipated 16% for children with a dual family history of allergic disease.
This “may have reduced our ability to detect an effect of the dietary intervention (although the confidence interval does not rule out the possibility of a clinically important 30% risk reduction)”, according to the researchers.
That 16% figure came from Australian data gathered before guidelines changed in 2016, when parents were advised to avoid introducing eggs and peanuts until after 12 months of age, to recommending they be introduced within the first 12 months. The guidelines have since been updated again to recommend the introduction of these foods soon after starting solid foods.
Research since then has shown that the guideline changes were associated with parents introducing egg and peanut at around six months and reduced prevalence of IgE-mediated egg and peanut allergies.
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A 2018 study had already shown that avoiding allergenic foods during pregnancy didn’t reduce the risk of children having those allergies, but there wasn’t much evidence to suggest what the right amount of allergenic food ingestion during pregnancy and breastfeeding was, they said.
Previous research showed that egg-specific immune responses were established at four months of age, so introducing eggs when babies started eating solids (at four to six months) could be too late to have any effect on the allergy.
“Regulatory immune tolerance responses to maternally derived antigens, including allergens, develop in the fetus,” the authors explained.
“Food allergens have been detected in amniotic fluid, where they reach the fetal gastrointestinal tract after swallowing. In the postnatal period, food allergens secreted in breast milk are likely to be another important early route of exposure, which, in studies in animals, has been shown to induce tolerance.”
In animal studies, that early exposure had been shown to induce tolerance in offspring, they noted.
Other studies showed that babies eating more eggs and peanuts had lower incidence of allergies to these foods, and mothers eating more peanuts and tree nuts while breast feeding was associated with lower allergy rates among their children.
