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  • Why are peanut allergies suddenly becoming more common in North America than elsewhere in the world?

    Posted on December 1st, 2010 admin No comments

    Nobody gave the answer I was looking for.  The answer from @jchaager is probably at least partly correct:  “Parents are raising their kids in a bubble and preventing early exposure to allergens that would build up their immunity.”

    The “overprotective parents” hypothesis (or “hygiene hypothesis”) of increase of allergies is probably at least partly true, but doesn’t lend itself to experimental verification.  What parent would agree to raise their child in “dirty” conditions for experimental purposes?  Nevertheless, there is some anecdotal support of the idea.  On the other hand, there is also experimental support of the idea that exposing a child to an allergen too early may trigger an allergy rather than boost their tolerance.

    Anyway, there is a biochemical and cultural cause that is hypothesized as a reason for increased peanut allergies in North America.  In North America, most peanuts are roasted, rather than boiled.  Boiling, as done in most of the rest of the world, neutralizes some allergens in peanuts.

    One of the main allergens in peanuts is “Ara h2,” which inhibits protein digestion.  Roasting peanuts makes this protein more effective at blocking protein digestion.  Thus, once a person with peanut sensitivity ingests Ara h2, other undigested proteins in the peanuts cause further allergic reactions.  Boiled or raw peanuts have less effective Ara h2, so are far less likely to trigger allergic reactions than roasted peanuts.

    More specifically, Ara h2 inhibits the action of the enzyme trypsin in the digestive system, which normally breaks down the peptide chains in proteins, liberating the component amino acids.  These undigested peptides are thought to be a contributor to the abdominal symptoms of peanut allergies.

    More about peanut allergies:

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