Why are Allergies Getting Worse?

Evidence suggests that our obsession with avoiding all germs is extreme. House Call Doctor explores the hygiene hypothesis.

House Call Doctor,
April 6, 2012

Scientific data supports the fact that more people are having allergies, and these levels are increasing over time. In a world where we are more clean and sterile, where we are exposed to less serious disease than ever in human history, are our immune systems getting confused and attacking things that aren’t even a threat?

One of the most popular theories as to why allergies are on the rise is the hygiene hypothesis, which suggests that the relative sterility of our environment is causing worse allergies. It seems that we are not keeping our immune systems busy enough and so they are inventing things to do, such as atatcking our own bodies. Evidence supporting this theory includes:

  • Immigrants from developing countries see a sharp rise in allergies when coming to industrialized countries.

  • Children in larger families have less allergies than do only children.

  • People with certain parasitic infections have a much lower rate of allergies and asthma. (A very interesting episode of This American Life describes a man who was cured of severe allergies by getting a hookworm infection on purpose!)

So am I suggesting that we should imitate that gross guy at work who doesn’t believe in hygiene? No, but I am suggesting that perhaps our obsession with avoiding all germs is extreme and is actually, at least partially, to blame for our overacting immune systems.

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