The Hygiene Hypothesis -- Redefine, Rename, or Just Clean It Up?

Linda Brookes, MSc; Laurence E. Cheng, MD, PhD


April 06, 2015

In This Article

Does Eating Peanuts Reduce Peanut Allergy?

An investigation of the extended hygiene hypothesis was reported from a trial in infants aged younger than 11 months at high risk for peanut allergy, which is the leading cause of anaphylaxis and death related to food allergy in the United States.[22] In the Learning Early about Peanut Allergy (LEAP) trial, children aged 4-11 months who were randomly assigned to consume peanuts up to 60 months of age showed significantly reduced frequency of peanut allergy development and modulated immune responses to peanuts.[23] "This paper emphasizes that although we don't necessarily know what we can do to prevent global allergy, we can do something about specific food allergies, even in high-risk children," Dr Cheng said. "This paper is useful in that it validates cultural norms present for generations in other parts of the world, which is earlier introduction of food than we have previously recommended in the United States," he continued. "This is the first evidence scientifically that early exposure to food may be of benefit in those who are otherwise destined to develop food allergy, and it is something that we should consider codifying for the future." Dr Cheng added that it was particularly interesting that the children would be presumed to have similar microbiomes to others living in urban Western environments, with a predisposition to allergic responses. By early introduction of food, "you might be able to get them on a different track. You are not predestined to allergy; rather, there is a way to modulate the outcome."

Although the LEAP trial was "an extremely provocative and landmark study, there were some hiccups along the way, as many of the children who ingested peanuts had eczema flares and what in the paper were called viral skin infections. Peanut-ingesting children also had more upper respiratory tract infections," Dr Cheng cautioned. "Whether this will bear out in even larger populations remains to be seen, but regular ingestion of peanuts by at-risk children with eczema wasn't achieved without some perseverance. It might be difficult for some families to knowingly worsen their child's eczema in the hopes of preventing a problem that is not apparent on a daily basis. That can be a tough decision to make, but most of the families in the trial pushed through and successfully completed the trial." Nonetheless, Medscape readers should be aware that some of the children stopped taking the peanuts, and many of these children ended up having food allergies. "So you don't know whether it was perseverance that made it work or whether the development of allergy in some children was so pervasive that it forced you to stop, no matter what the potential benefit," Dr Cheng stressed.


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