CAMBRIDGE, MA -- Trillions of bacteria live in each person's digestive tract. Scientists believe that some of these bacteria help digest food and stave off harmful infections, but their role in human health is not well understood.
To help shed light on the role of these bacteria, a team of researchers led by MIT associate professor Eric Alm recently tracked fluctuations in the bacterial populations of two research subjects over a full year. The findings, described in the July 25 issue of the journal Genome Biology, suggest that while these populations are fairly stable, they undergo daily fluctuations in response to changes in diet and other factors.
"On any given day, the amount of one species could change manyfold, but after a year, that species would still be at the same median level," says Alm, the Karl Van Tassel Career Development Associate Professor of Biological and Environmental Engineering and senior author of the paper. "To a large extent, the main factor we found that explained a lot of that variance was the diet."
Alm and Lawrence David, an assistant professor at Duke University and the paper's lead author, began the study in 2009, around the same time the National Institutes of Health launched the Human Microbiome Project an effort to analyze the composition of bacterial communities found in humans, including the gut but also other organs such as the skin, nasal passages, and mouth.
There are a few thousand strains of bacteria that can inhabit the human gut, but only a few hundred of those are found in any given individual, Alm says. For one year, the two subjects in the study collected daily stool samples so bacterial populations could be measured. They also used an iPhone app to track lifestyle factors such as diet, sleep, mood, and exercise, generating a huge amount of data.
Analysis of this data revealed that dietary changes could produce daily variations in the populations of different st
|Contact: Sarah McDonnell|
Massachusetts Institute of Technology