January 2007 Archives

Gut Bugs in the News

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The teeming bacterial kingdom in our digest tract is certainly getting its “15 minutes of fame” thanks to the research of gastroenterologist-turned-microbiologist Jeffrey Gordon and his team of young post-docs at Washington University, in St. Louis.

In December, Gordon’s crew extended their string of high-profile papers with two Nature reports. One describes how weight loss produces a profound change in what lives in our guts.


The other documents how the Wash U researchers found they could send germ-free mice down the road to either leanness or obesity by inoculating the animals’ intestinal tracts with either a “lean microbiota” or an obesity-related one (either the Bacteroides thetaiotaomicron or Eubacterium rectale, respectively).The reports generated scads of press on “microbesity” and “fat microbes,” with the unfortunate implication that weight gain was the result of some kind of infection to be eradicated.

This new interest in our previously ignored “nation within” is also generating interest in more obscure research. This week, for instance, The New York Times reported on a paper published in the December issue of the Journal of Clinical Pharmacy and Therapeutics. In it, University of Arkansas graduate student Laura Hill reports how a 10-day course of the so-called “cold-busting” herb echinacea produced a dramatic shift in the intestinal microflora of 15 volunteers--boosting the concentration of aerobic, or air-breathing bacteria (normally a tiny portion of our intestinal flora), as well as that of the Bacteroides group in general and Bacteroides fragilis in particular.

While a normal part of a health intestinal microflora, a high concentration of Bacteroides has been associated with elevated risk of colon cancer, Hill points out, while certain strains of B. fragilis may contribute to inflammatory bowel disease in those predisposed to the condition.

Hill and her professor, UA food scientist Jerald Foote, express alarm over the finding that just 10 days on echinacea produced a significant shift in their volunteers’ microflora, as this herb has long been accepted as safe to use for up to eight weeks. Many people pop a capsule of concentrated extract daily throughout the cold and flu season.

Given our intestinal bacteria’s chief function--helping our bodies break down and absorb a broad variety of plant nutrients--neither Gordon’s findings nor Hall and Foote’s should come as any surprise. After all, every one of us knows all too well how the foods we eat produce profound effects on the microbial activity inside our guts: As babies it made us cry, as teenagers it made us laugh, and as adults, it makes us cringe with embarrassment. I’m talking, of course, about the flatulence that result whenever we feed our hydrogen-producing intestinal bacteria. (Around a third of us likewise host one or more methane-producers.)

The extra calories liberated by these micro-digestive processes have long ensured our species’ survival in lean times. That it’s now being blamed on obesity strikes me as akin to blaming weight gain on having a fully functional stomach.