From <a href="http:&#x2F;&#x2F;americangut.org&#x2F;our-results-so-far&#x2F;" rel="nofollow">http:&#x2F;&#x2F;americangut.org&#x2F;our-results-so-far&#x2F;</a> - &quot;The American Gut project has many more samples representing more groups of people than other studies, such as the Human Microbiome Project, Global Gut, or Personal Genome Project.&quot;<p>No hard numbers on their site, but there&#x27;s over 7500 contributors on their sample collection kit fundraising page.