Your gut is full of bacteria that help keep you healthy.
Now scientists want to study whether those bugs are different in vegetarians and Atkins dieters, or in couch potatoes and athletes.
To participate will require mailing a stool sample and paying a fee -- $69 and up.
That may be a lot to ask, but the researchers running two novel citizen-science projects hope a lot of people sign up.
The American Gut Project aims to enroll 10,000 people from all walks of life.
Separately, uBiome is aiming for nearly 2,000.
It's a first step toward understanding which combinations of bacteria are the healthiest -- and which are linked to health problems.
The big question is whether we might be able to change our bacteria through diet and lifestyle.