Early exposure reduces common food allergies

It may seem counterintuitive, but exposing infants to allergenic foods from an early age may reduce the likelihood of them developing full-blown allergies and autoimmune disease later in life.

A new study from the Imperial College London analysed data covering the last 60 years and has determined that introducing egg and peanuts to the diets of infants as young as four months can help reduce allergic sensitisation.

A team of researchers led by Dr Robert J Boyle screened over 16,000 studies looking at allergenic food introduction and determined that early exposure to egg and peanut is preferred, while the data concerning the introduction of fish and gluten was less conclusive.

Dr Boyle’s team conducted a systematic review and meta-analysis of intervention trials and observational studies dating back to 1946. They focused on studies that evaluated timing of allergenic food introduction and also looked at allergic sensitisation and autoimmune disease.

Since 2008, there has been a general move away from infant feeding guidelines advising a delay in the introduction of allergenic foods, but this is the first comprehensive review of the evidence for early introduction to known allergens.

The researchers found moderate-certainty evidence that early egg introduction at 4–6 months was associated with reduced egg allergy; moderate-certainty evidence that early peanut introduction at 4–11 months was associated with reduced peanut allergy; low-certainty evidence that early fish introduction was associated with reduced allergic sensitisation and rhinitis; and high-certainty evidence that timing of gluten introduction was not associated with coeliac disease risk.

Dr Boyle pointed out that families with a history of allergies should still consult specialists before introducing these foods, saying, “The imprecise effect estimates, issues regarding indirectness and inconclusive trial sequential analysis findings all need to be considered, together with a careful assessment of the safety and acceptability of early egg and peanut introduction in different populations.”

The Australasian Society of Clinical Immunology and Allergy recommends the introduction of peanut butter, cooked egg, dairy and wheat products to infants’ diets at around six months, while still breastfeeding, but also points out that the reasons for the continued rise in allergic diseases is not well understood. These include food allergy, eczema, asthma and allergic rhinitis (hayfever).

This study was published in the Journal of the American Medical Association.

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