The first major results from the American Gut Project, a crowdsourced, global citizen science effort, were published today in mSystems.
According to researchers from the University of California San Diego School of Medicine, this project provides the largest public reference database of the human gut microbiome, which may help drive many future microbiome studies.
"We observed a much greater microbial diversity than previous smaller studies found, and that suggests that if we look at more populations, we'll see more diversity, which is important for defining the boundaries of the human microbiome," said Daniel McDonald, PhD, scientific director of the American Gut Project.
The American Gut Project was co-founded in November 2012. The project's goal is to better understand human microbiomes. To do this, citizen scientists contribute $99 and receive a kit to collect a fecal, oral or skin swab and instructions to mail it back. Along with the sample, each participant also answers a voluntary survey that includes questions about general health status, disease history, lifestyle, and diet.
As of mid-2017, the project included microbial sequence data from 15,096 samples provided by 11,336 people, representing primarily the United States, United Kingdom, and Australia. All of the data collected by the American Gut Project are publicly available, without participants' identifying information.
Among the findings reported was that the number of plant types in a person's diet plays a role in the diversity of his or her gut microbiome. No matter the diet they prescribed to (vegetarian, vegan, etc.), participants who ate more than 30 different plant types per week had gut microbiomes that were more diverse than those who ate 10 or fewer types of plants per week.
Also, the gut microbiomes of participants who reported that they took antibiotics in the past month were, as predicted, less diverse than people who reported that they had not taken antibiotics in the last year. But, paradoxically, people who had taken antibiotics recently had significantly greater diversity in the types of chemicals in their gut samples than those who had not taken antibiotics in the past year.
Most of the findings emerging from the American Gut Project so far are simply observations or associations, and in many cases researchers can't yet extrapolate the ultimate effect on human health. For example, while the researchers observed that people who eat many plants have a more diverse gut microbiome than those who don't, they don't yet know if increasing a person's microbial diversity from its current level would have a direct positive effect on his or her health.