Maternal diet doesn't affect baby's food allergy risk

Higher maternal consumption of egg and peanut during pregnancy and breastfeeding does not protect infants against developing egg or peanut allergies in their first year of life — contradicting previous findings — according to a landmark Australian study published in The New England Journal of Medicine.

Scientists have long suspected that exposure to certain food proteins in the womb and through breast milk may influence a child’s immune development. But while previous observational studies suggested a possible benefit, high-quality evidence from large randomised controlled trials had been lacking.

Seeking to resolve this, the PrEggNut Study — one of the largest food allergy prevention trials ever undertaken — recruited more than 2100 pregnant and breastfeeding women from across Australia. All participants were carrying babies considered at increased risk of allergy due to a strong family history of allergic disease.

Researchers compared mothers who consumed a diet rich in eggs and peanuts, including at least six eggs and 60 peanuts each week, with mothers who followed a standard diet containing no more than three eggs and 30 peanuts per week. The dietary intervention began before 23 weeks of pregnancy and continued until four months after birth during breastfeeding.

When infants were assessed at one year of age, researchers found no significant difference in allergy outcomes between the two groups. Approximately 8% of infants in both groups developed an egg or peanut allergy, providing definitive evidence that higher maternal consumption did not reduce the likelihood of developing food allergy.

“We had expected that the mothers eating higher amounts of eggs and peanuts during pregnancy and breastfeeding would have reduced egg and peanut allergies in their babies,” said lead author Associate Professor Debbie Palmer, Head of the Nutrition in Early Life team at The Kids Research Institute Australia.

“However, we found no difference between the two groups.”

The good news is, the higher intake of eggs and peanuts was found to be safe for both mothers and infants, with no meaningful differences in serious adverse events, hospitalisations or allergic reactions between the groups. As noted by Palmer, “There were … no indications that higher maternal egg and peanut ingestion reduced (or increased) the risk of infant egg or peanut sensitisation, egg or peanut allergy individually, or eczema.”

Importantly, the findings reinforce existing evidence supporting the introduction of common allergenic foods such as egg and peanut directly into an infant’s diet during the first year of life, which remains a key strategy for food allergy prevention.

“For food allergy prevention, our best current advice is to include well-cooked egg (such as mashed hard-boiled egg) and smooth peanut butter mixed in with the baby’s solid foods, starting soon after they have commenced eating solid foods, and continuing to include egg and peanut regularly in the baby’s diet at least once a week,” Palmer said.

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