What Lives in Your Gut?

As we enter a new year, many of us will start thinking—if only temporarily—about improving our diet and lifestyle habits. Maybe you'll resolve to drink more water, eat less fat, get more exercise.

But what does your gut want? A new citizen science project aims to find out.

"What diet should you be eating to achieve an optimal, healthy microbiome in your gut? We don't know yet but finding out could be the key to helping people overcome many chronic diseases," said Jeff Leach, co-founder of the American Gut project.

(Read about the secret world of microbes in the January 2013 issue of National Geographic magazine.)

The concept of the crowd-funded project is simple: Pay $99, get a sample collection kit, and mail back a test tube containing "a little bit of brown" swabbed from your used toilet paper. Participants will also be asked to log their food intake for three days and answer a detailed questionnaire about how and where they live.

"Are you a vegetarian? Were you born via C-section? Do you live in a rural or urban area? Do you have dogs? All of these things can influence your microbiome," Leach said.

In return, participants will receive an analysis revealing what organisms dwell in their gut and showing how their own microbial ecosystem compares to others—including a group of hunter-gatherers Leach has been studying in Tanzania. (That research has not yet been published, but he says it reveals "big differences" between the guts of people who consume a Western diet of highly processed foods and those who eat more traditional diets.)

"There's been a lot of research about the human microbiome recently, but the general public never gets to figure out what's in their gut unless you do something like this," said Leach.

Microbes play several vital roles in the gut, including maintaining the mucosal lining of the gastrointestinal tract, protecting against pathogens, and helping the body harvest calories and digest fiber.

Having too much or too little of certain bacteria could contribute to inflammation, a key factor in many chronic diseases. Recent studies have linked diabetes and obesity to imbalances in gut bacteria.

"We want people to understand that this is a major aspect of their health that's in their control," Leach said. "You're born with your genes, but you can shift your microbiome through diet and lifestyle changes."

About a thousand people have joined the project so far, and Leach is hoping another 3,000 or more will sign up to receive a kit before the February 1 deadline.

For more information, visit the American Gut Project http://humanfoodproject.com/american-gut/.