I’ve suspected for quite a while that the “epidemic” of food allergies and other ailments among today’s children was related to the extremely hygienic conditions of modern homes (that is, kids’ immune systems were insufficiently stressed by exposure to germs, which meant higher risk of immune system over-reaction later in life). I’m not a scientist, so my suspicion was just based on less-than-statistically valid observation of my son and his friends while they were growing up — the kids with the most sterile home environments did seem more likely to have serious allergy issues come up later.
I could have been on the right track, after all:
I do wonder, however, whether we’re all becoming a bit too paranoid about germs. I include my own family in this group. Once we left the doctors’ office, for example, my wife and I encouraged our children to use a hand sanitizer. When our kids were toddlers our house had alcohol wipes and Purell vials all over the place. But is all this washing and disinfecting really necessary? Is it proactive prevention? Or overly paranoid fear?
That, at least, is the thinking behind the “hygiene hypothesis,” a school of thought first proposed by David P. Strachan in 1989, and now experiencing a resurgence that’s probably a response to society’s mania for cleanliness. Strachan’s original study sought to explain why British kids with greater numbers of older siblings had fewer incidences of hay fever, speculating that perhaps it could be the fact kids with lots of older siblings tend to be exposed to greater numbers of germs. While it was greeted with skepticism early on, Strachan’s theory has since been confirmed. In fact, in the decades since, greater exposure to germs early in life has also been associated in epidemiological studies with lower levels of asthma, some allergies and even such autoimmune diseases as type-1 diabetes and multiple sclerosis.
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“These data support the idea that the greater diversity of microbial exposure among children who live on farms is associated with the protection from the development of asthma,” study researchers reported, speculating that microbial exposure may encourage development of immune system cells that in turn suppress the production of the sort of immune-system cells that trigger asthmatic reactions. Researchers’ next hope to determine which microbes are most responsible for preventing asthma — and that, perhaps, may lead to new therapies, such as targeted microbe exposures, for the dreaded respiratory malady.
More broadly, the study is a reminder that humans have been living and fighting off germs for tens of thousands of years. Particularly when we’re young, germs serve an important purpose for the development of the immune system. By depriving our children of exposure to germs, we may be depriving them the benefits of a process the human body has evolved over aeons, a process that helps to create healthy and allergy-free adults.
