FEATURE ARTICLE
Why We Develop Food Allergies
Coached by breast milk and good bacteria, the immune system strives to learn the difference between food and pathogens before the first morsel crosses our lips
Per Brandtzaeg
Last Course
Zooming out from all this complexity, the phenomenon of oral tolerance rests on a few primary processes: SIgA antibodies, the barrier function of the gut epithelium, the timing and dose of inoculation with commensal bacteria, and family history. These variables are interdependent, and no single factor predominates in maintaining mucosal homeostasis. There is no single cause of food allergy.
From an evolutionary perspective, intolerance to certain dietary antigens is not too surprising. It has not been long since human beings began growing and preparing their food rather than hunting and gathering it. And evolution is slow when the undesirable phenotype is so seldom deadly.
We must also keep in mind that the current epidemic of allergy in industrialized countries is a small price to pay for the remarkable reduction of infant mortality provided by the elimination of pathogens through improved hygiene. Having too few microbes in our immediate environment seems to be problematic, but having many pathogens is far, far worse. Nevertheless, the pace of research raises hope that future therapies will compensate for the missing good microbes needed to develop homeostasis of mucosal immunity.
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