Eating more eggs and peanuts in pregnancy did not prevent infant allergy

Design

Multisite randomised controlled trial

Population

2,137 pregnant women with an unborn child at high familial allergy risk

Primary outcome

IgE-mediated egg or peanut allergy in the infant at one year

Effect

7.8% vs 8.4%; relative risk 0.93 (95% CI 0.69-1.26)

PrEggNut tested whether increasing maternal allergen intake could prevent food allergy in high-risk infants. Pregnant women whose unborn child had at least two close relatives with allergic disease were randomised to a high egg-and-peanut diet (at least six eggs and sixty peanuts weekly) or a standard lower-intake diet, from before 23 weeks' gestation through four months of breastfeeding.

There was no difference. IgE-mediated egg or peanut allergy at one year occurred in 7.8% of infants in the high-intake group and 8.4% in the standard group, a relative risk of 0.93 with a confidence interval spanning no effect. Safety was similar.

The finding closes off maternal diet loading as a prevention strategy. It does not undercut the separate, well-supported approach of introducing allergenic foods early to the infant, which remains the evidence-based lever for families worried about allergy.

• Randomised 2,137 pregnant women whose unborn child had a strong family history of allergy.
• High maternal intake was at least six eggs and sixty peanuts per week through pregnancy and lactation.
• Infant IgE-mediated egg or peanut allergy at one year was 7.8% versus 8.4%.
• The relative risk was 0.93 (95% CI 0.69 to 1.26), consistent with no effect.
• Advise early introduction of allergenic foods to the infant instead of maternal diet loading.

Why it matters

It removes a plausible-sounding prevention strategy that the trial shows does not work.

Don't overread it

A null result for maternal diet does not speak against early introduction of allergens to the infant, which does reduce allergy.

The statistics, in plain English

A relative risk of 0.93 with a confidence interval from 0.69 to 1.26 crosses 1.0, so any difference is statistically indistinguishable from none. The trial was large enough to make a meaningful benefit unlikely.

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