The busy world inside

DEEP inside each of us is a vast ecosystem, as complex as the soil or the oceans, that helps us digest food and contributes to our health and well-being. Now scientists from the Institute for Genomic Research in Rockville, Md., have carefully cataloged the teeming life inside the human colon for the first time.

Among the findings, published last week in Science: The thriving community contains as many as 100 trillion microbes, representing more than 1,000 species, and includes more than 60,000 distinct genes -- twice as many as in the human genome.

To conduct their study, the scientists collected fecal samples from two anonymous people who had not taken any medication for a year. Then they used molecular analyses to assess the diversity of microbes in the colon. They found, among other things, that the gut-dwelling microbes synthesize vitamins and break down sugars that humans could not otherwise digest.

They hope, down the road, that monitoring or altering genes inside the colon will provide early signs of illness, new ways to optimize nutrition, and perhaps even new ways to predict how much of an oral medication could be absorbed.

“We have begun to define what is present in a healthy gut,” said lead author Steven Gill, formerly at the institute but now an associate professor at the State University of New York in Buffalo. “The interesting aspect will come down the road when we look at samples from more people -- people with different diets, different ethnic backgrounds, different ages and sexes.”