LEAP study finds peanut consumption can protect infants at risk of developing peanut allergy

Peanut allergy, which affects 1 in 50 children in the UK, is one of the most high risk allergens, alongside tree nuts, milk and egg.

However, a new study of peanut allergy in those aged 4-11 months has noted that the majority of infants at high-risk of developing peanut allergy are protected from it by age 5 if peanuts are consumed frequently.

For many years Public Health Guidelines, Paediatricians and Allergists have recommended avoiding foods in infant’s diet that cause allergies such as peanut. However, the LEAP (Learning Early About Peanut Allergy) study led by Professor Gideon Lack, King’s College London, and published on Tuesday 24th February 2015 in the New England Journal of Medicine, is the first study to show that consumption is an effective strategy to prevent food allergy, contradicting previous recommendations. 

The incidence of food allergy has risen in recent decades, and the occurrence of peanut allergy has more than doubled in the last 10 years in the UK and North America. It affects between 1-3% of children in Western Europe, the USA, and Australia and in recent years has become an important cause of food allergies in African and Asian countries. Peanut allergy usually develops early in life, is rarely out-grown and there is currently no cure. It imposes a considerable burden, impacting negatively on quality of life for patients and their families.

The LEAP study, a randomized controlled trial, enrolled 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. To determine whether peanut consumption or avoidance is the most effective strategy to prevent peanut allergy, 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. Adherence to peanut consumption or avoidance advice was assessed using a food frequency questionnaire at regular intervals during the study and by measuring peanut levels in the child’s home environment.

Remarkably, 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. Even when considering all children enrolled – including those participants who were unable to tolerate peanut consumption (13 of the 319 children who were randomised to peanut consumption had some allergic responses to peanut during the study) – a powerful protective effect against the development of peanut allergy remains: the overall prevalence of allergy in all children asked to consume peanut was 3.2% versus 17.2% in the avoidance group. This represents a greater than 80% reduction in the prevalence of peanut allergy. Nearly all participants enrolled on the LEAP study completed the final assessment at age 5 years (98%). 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.

The study was therefore able to conclude that early, sustained consumption of peanut is safe and associated with a substantial and significant decrease in the development of peanut allergy in high-risk infants by the age of five.  Deliberate avoidance of peanut in the first year of life is consequently brought into question as a strategy to prevent allergy.

Professor Gideon Lack, Head of Department of Paediatric Allergy, King’s College London, presented the findings at the American Academy of Allergy, Asthma and Immunology meeting (AAAAI): “This is an important clinical development and contravenes previous guidelines. Whilst these were withdrawn in 2008 in the UK and US, our study suggests that new guidelines may be needed to reduce the rate of peanut allergy in our children.”

Professor Lack further noted that: “The study also excluded infants showing early strong signs of having already developed peanut allergy; the safety and effectiveness of early peanut consumption in this group remains unknown and requires further study. Parents of infants and young children with eczema and/or egg allergy should consult with an Allergist, Paediatrician, or their General Practitioner prior to feeding them peanut products.” 

Dr George Du Toit, co-investigator of the study said: “The next stage of our work, the LEAP-On study, will continue to monitor those children who consumed peanut to see if they remain protected against allergy even if they stop consuming peanut for 12 months. The LEAP-On study will help establish if the protection provided against the development of peanut allergy is sustained and not dependent on ongoing peanut ingestion.”

Anaphylaxis Campaign CEO, Lynne Regent, said: “This is an exciting and important study that is likely to inform future guidance for parents.  In the meantime, parents of atopic children should seek advice from their child’s allergy specialist or treating doctor before introducing peanuts into their diet.”

Dr Andrew Clark, a leading allergy specialist at Addenbrooke's Hospital in Cambridge, and Chair of the Anaphylaxis Campaign's Clinical and Scientific panel, said: "This study could be a turning point in the way we try to prevent food allergy in the future, it really does prove a principle that it is possible to reduce the prevalence of peanut allergy early in childhood by feed infants peanut in a careful and controlled way." 

"But we should remember this study was carried out at an internationally renowned centre, and they selected children at quite low risk of a severe reaction.

"Don't try this at home."