Stemming the Tide of Allergens (Public Evening Lecture) - review

01 December 2016

On Tuesday 29 Nov, Professor Gideon Lack, of Kings College London, gave SCI’s public evening lecture on how appropriate exposure to certain foods could prevent later food allergies in certain high-risk children. This interesting talk, focusing on prevention rather than cure and drawing heavily on professor Lack’s own research in the field, was very well-attended, with many questions at the end.

Professor Lack opened the lecture by comparing immunology to the study of war and peace. In this comparison, he said, peace is the body tolerating and co-existing with possible triggers (such as pollen, etc); a war of self-defence is the body fighting infection; civil war is the body’s immune system fighting itself (such as diabetes, lupus, etc); and wars of aggression are allergies – the body’s inappropriate specific immune response to food protein. With that illuminating evaluation, he proceeded to discuss the evidence for the relationship between early eczema and food allergies.

The theory that his research was based on is that the body expects to be exposed to food orally. Cutaneous exposure, such as that enabled by eczema, is not responded to in the same way by the body, which identifies the food particle as an attacker. In his LEAP study (read more about that study here), a randomised controlled trial, 640 children aged 4-11 months, who were considered at high-risk of developing peanut allergy due to pre-existing severe eczema and/or egg allergy were enrolled. Half of the children were asked to eat peanut-containing foods three or more times each week and the other half to avoid eating peanut until 5 years of age.

Less than 1% of children who consumed peanut as per study protocol and completed the study developed peanut allergy by 5 years of age, while 17.3% in the avoidance group developed peanut allergy. Importantly, the early introduction of peanut-containing foods was found to be safe and well tolerated; infants were not fed whole peanuts, which carry a risk of choking in young children.

Professor Lack highlighted alternative popular theories about allergens, including the hygiene hypothesis and vitamin D deficiency and also noted interesting points in the data, such as the allergy rates among children whose genetic origin and location did not match (there are particular high rates of allergy in Caucasian children in the USA and Australia, for instance).

He then discussed further studies: the LEAP-ON study demonstrated that early peanut consumption in at-risk infants persists after a one-year period of avoiding peanut – only 4.8% of the original peanut consumers were found to be allergic, compared with 18.6% of the original peanut avoiders, a significant difference. Read more about that study here. The EAT study, which introduced various ‘problem’ foods into the diets of non-high risk, exclusively breast-fed babies from 3 months to 3 years, was also discussed. Professor Lack noted that, while the results from the general population study were not statistically significant, there was a 67% reduction in the per-protocol group – a marked, although not conclusive, result.

Professor Lack cautioned that the results needed to be interpreted carefully and again highlighted other theories, but did say he agreed with the New England Journal of Medicine review of the EAT study, that ‘evidence is building that early consumption rather than delayed introduction of foods is likely to be more beneficial as a strategy for the primary prevention of food allergy’.

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