Why have peanut allergy cases tripled in the last 10 years?

More than 3 million Americans now have some kind of nut allergy, with cases of peanut allergy in children more than tripling between 1997 and 2008, according to a report released in May 2010.  Other food allergies have risen also, and nobody is certain exactly what is behind this spike.

Here’s one theory that makes a lot of sense to me (from livescience.com):

In general, those with food allergies have extra-sensitive immune systems that react to harmless substances called allergens found in certain foods and drinks. When the person eats a peanut or other allergic item, the body produces antibodies to the specific allergen, leading to an immune reaction. Essentially, the body tries to get rid of the allergens.

One idea for the cause called the hygiene hypothesis posits we’re too clean. Squeaky-clean living and the use of medications to prevent and quickly treat infections leaves the immune system under-stimulated. This “bored” immune system then goes and attacks harmless proteins like those in foods, pollens and animal dander.

Hmm – interesting.  For a long time, it’s seemed like generally a bad idea to be so germ-phobic, grabbing for the hand sanitizer over and over for no really good reason.  My gut feeling was that our immune systems need to be exercised in order to be kept “in shape”, much like one would exercise a muscle.  It didn’t occur to me that the immune system would start to concentrate on smaller and smaller “threats” if deprived of real bacteriological issues to deal with.  Either way, while sanitation and personal hygiene are very good things, we need to draw the line and stop being phobic about it.