Human Gut Check

Human Gut Check Finds Bacteria Sorted in Ways That May Aid in Treatments

By Cecile Vannucci – Apr 20, 2011 12:00 PM CT

Scientists have categorized trillions of bacteria that live in the human gut into three types of systems that may one day be used to diagnose and treat colon cancer and inflammatory bowel disorders.
An international consortium of researchers studied stool samples from residents of Denmark, France, Italy, Spain, the U.S. and Japan to make the finding, according to a report published in the journal Nature. Their analysis found that every person’s gut bacteria belongs to one of three groups, or enterotypes, and that variation in gut microbes aren’t related to race or nation.

Intestinal bacteria are essential for health. They help convert food into energy and guard against pathogens that cause sickness. The finding is the first classification of human gut bacteria, and may one day lead to earlier diagnosis of colon cancer, better understanding of bowel disorders such as Crohn’s disease and of the effects of obesity, the authors said.

“It was a surprise and it’s good news as any classification helps to digest knowledge,” Peer Bork, one of the study’s authors and a researcher at the European Molecular Biology Laboratory in Heidelberg, Germany, said in an e-mail. “Also it generates simple and practical hypothesis toward digestion and response to drugs.”
Confirming Enterotypes

The researchers first looked at 33 samples from Danish, French, Italian, Spanish, Japanese and American people. They confirmed the enterotypes in larger stool samples from 85 Danish and 254 Americans, Bork said in an e-mail. Using DNA analysis and computers, the scientists identified three clusters of gut bacteria that weren’t specific to nationality or continent.

The three enterotypes were classified into groups named for the predominant bacteria in the cluster: Bacteroides, Prevotella and Ruminococcus. Researchers noted some differences in vitamin production among the groups. People in the Bacteroides group had microbes that produced more vitamin C, B2, B5 and H, while the Prevotella group had more B1 and folic-acid producing bacteria.
The data may be biased because the sample didn’t include people from remote villages with a traditional diet, Bork said.

“Our knowledge of species and functional composition of the human gut microbiome is rapidly increasing, but it is still based on very few cohorts and little is known about variation across the world,” the report said.
Additional studies may lead to a better understanding of microbial properties that correlate with health, diet or drug response, researchers said.

The study was done as part of the metagenomics of the Human Intestinal Tract collaboration, which aims to understand the effect of gut bacteria on health. The collaboration includes European and Chinese research institutions as well as industry and pharmaceutical companies.
To contact the reporter on this story: Cecile Vannucci in New York at

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