Although the American Gut is useful, by design it is not intended to provide an unbiased population but rather to harness crowd funding and public enthusiasm to uncover the range of extant microbiomes. Given this fact, many questions could be best addressed by instead adding microbiome components to existing carefully designed cohorts such as NHANES [58], the Nurses’ Health Study [59], and TwinsUK [60]. Relevant areas of inquiry include relating the microbiome to heart disease, cancer, stroke, cognitive abilities, and host genetics, as well as leveraging new avenues to assess sources of technical variation. These studies offer the unique potential to build off of their already well-characterized populations.
