Wednesday, April 27, 2016

What our gut tells us about the 'hygiene hypothesis'

Over the past few decades, the healthcare community has observed an intriguing phenomenon: diseases related to the immune system—type 1 diabetes (T1D) and other autoimmune diseases, allergies, and the like—have taken hold in countries that have thriving, modern economies, while barely making a mark in the developing world. One of the best-supported theories to explain this peculiar public health pattern has been dubbed the “hygiene hypothesis.” The theory is based on the premise that exposure to pathogens early in life is actually beneficial to the education and development of the human immune system and that the sanitary conditions in “westernized” countries ironically hamper our natural immunity.

“If you look across the world geographically where incidence of autoimmune disease and allergies are high (and it’s mostly in the western world—America and Europe, etc.) and then superimpose a map that shows where diarrheal diseases and bacterial infections occur, you’ll see very little overlap. That suggests that exposure to bacteria and other ‘bugs’ may play a pivotal role in the immune system, and that we might be able to understand what that role is by studying the human microbiome,” says Aleksandar Kostic, a postdoctoral fellow in the lab of Ramnik Xavier at the Broad Institute of MIT and Harvard and co-first author of a new paper that appears this week in Cell. Xavier is also chief of gastroenterology at Massachusetts General Hospital.

Link to full Broad Institute news release

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