In the first published study of the American Gut Project's work, which appeared in the American Society for Microbiology's journal mSystems in May 2018, the researchers found that plant-heavy diets led to a more diverse bacterial colony in stomachs than people who ate comparatively fewer types of greens. Knight and his colleagues would love to analyze your poop in an effort to compile more information, but there is a catch: Donors have to pay a $99 fee to join the project, an informal kind of crowdfunding that keeps the research financed. If you submit a sample—basically a poop swab taken from your used toilet tissue—the team at Human Gut will send you a personalized microbiome profile and an assessment of how your gut flora compares with the rest of the population.