The bottom line is that the LEAP study demonstrates that consumption of a peanut-containing snack by infants who are at high-risk for developing peanut allergy prevents the subsequent development of allergy. Put another way, early dietary exposure to peanut allergen promotes the development of tolerance to peanuts in the child’s developing immune system and is highly effective in preventing allergic reactions to peanuts in later life.
The prevalence of peanut allergy has grown alarmingly over the past 10 years in western countries in particular, with 1 in 50 children in the UK and USA now thought to be allergic to peanuts. Peanut allergy is an abnormal response by the body’s immune system to harmless peanut proteins in the diet. This study was based on a hypothesis that regular eating of peanut-containing products, when started during infancy, will elicit a protective immune response instead of an allergic immune reaction.
The LEAP randomised controlled study – the first of its kind - enrolled over 600 British children between 4 and 11 months of age at high risk for peanut allergy to test whether consumption or avoidance of peanut until age 5 years would result in decreased incidence of peanut allergy. Children were randomly assigned to test consumption of a peanut-containing snack on a regular basis, or to avoid peanut consumption, for 5 years. The prevalence of peanut allergy in the 5-year-old children was then compared between the peanut consumption and the avoidance groups. Children in the peanut consumption arm of the trial ate a peanut-containing snack-food at least three times each week, while children in the peanut avoidance arm did not ingest peanut-containing foods.
The infants enrolled in the study had severe eczema and/or egg allergy, which put them at high risk of developing peanut allergy. Of the children who avoided peanut, 17% developed peanut allergy by the age of 5 years. Remarkably, only 3% of the children who were randomised to eating the peanut snack developed peanut allergy by age 5. Therefore, in high-risk infants, sustained consumption of peanut beginning in the first 11 months of life was highly effective in preventing the development of peanut allergy.
As Professor Gideon Lack, pointed out, “for decades allergists have been recommending that young infants avoid consuming allergenic foods such as peanut to prevent food allergies. Our findings suggest that this advice was incorrect and may have contributed to the rise in the peanut and other food allergies.”
Some people and parts of the media may have difficulty accepting this clinical finding because it seems counterintuitive that exposing high-risk children to strong doses of peanut allergens very early in life can prevent peanut allergy from developing when they encounter peanuts later. It is important to remember that precautionary advice about avoiding peanuts while pregnant or breastfeeding was withdrawn in the UK and North America in 2009 because it was shown to be ineffective in preventing increasing rates of peanut allergy in children. The evidence is now strong that early exposure is an effective way to encourage tolerance to peanut protein.
The American peanut industry knows there is still much to do to help everyone understand how the peanut allergy field has changed so dramatically in such a short space of time. The industry has supported the LEAP programme from the outset and will do everything it can to communicate accurately what the new results mean. Encouraging as LEAP is for the future, no one should be under the false impression that LEAP’s findings mean that peanut allergy is no longer a serious issue for many individuals who are already allergic or that the need for allergy-safe and evidence-based management practices and the provision of accurate information to allergic consumers has gone away. These will continue to be a main concern of the American peanut industry.
For the full journal article: http://www.nejm.org/doi/pdf/10.1056/NEJMoa1414850
For the accompanying editorial: http://www.nejm.org/doi/full/10.1056/NEJMe1500186