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The mystery of the rising food allergies: The Hygiene Hypothesis

Posted Sep 14 2008 1:33pm

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I mentioned in my post on the Food Allergies and Anaphylaxis Act that peanut allergies among children doubled within five years between 1997 and 2002. So what gives? Why are peanut (and other food) allergies on the rise?

The short answer is that we don’t know for certain. In order to solve the mystery we first have to figure how we get food allergies in the first place. Right now we don’t have any definitive answers, just a few ideas.

For some time it was believed that genetics and eating allergenic foods during pregnancy and nursing were the main contributors to children having food allergies. But neither of these explain the recent dramatic rise in food allergy, nor have studies consistently supported the theories.

Another idea that has been under consideration recently is what is called the “ hygiene hypothesis.” The idea goes, our immune systems need a few challenges in order to remain strong defenders of our bodies. If we do not present our immune system with sufficient stimuli it will start overreacting to other harmless stimuli, like the protein found in peanuts.

Welcome to modern life, the age of the antibacterial wipes! From the time we figured out that washing hands can kill germs we've been cleaning everything in sight. And we've done it believing that we're doing our immune systems a favor.

But has it been too much?

In 1989 David P. Strachan suggested it might be in an article published in the British Medical Journal. Strachan noted that hay fever and eczema, both allergy-related conditions, were less common in larger families than among only children. Presumably children with several siblings would be exposed to more microorganisms. About the same time a German researcher, Dr. Erika Von Mutius, found similar results while comparing rates of allergies and asthma in East and West Germany. Since this hypothesis was introduced other researchers have been testing it with other autoimmune diseases. The findings are not definitive, but there's something there.

But before you send your kids out to roll around in the dirt, keep in mind some recent research that shows that regulating your immune system is not just a matter of getting dirty. Erwin W. Gelfand, MD commented on a study involving exposure to horse stables. Apparently it was the specific "immunologic setting" of the farm that made the difference. Perhaps some microbes are better for our immune systems than others!

What do you think? Is the rise in food and other allergies a plague we've brought upon ourselves through cleanliness?

Next week I'll look into another possible clue to the mystery of rising food allergies, genetically modified food.

Find out more about the hygiene hypothesis in this Healthlink article, this Science Daily article and this explanation of the hygiene hypothesis from Allergic Child.

For a more technical look at the subject, read Erwin W. Gelfand's article on the hygiene hypothesis in MedScape Today

Image from Alternative Choice Therapy.

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