This text describes how the "healthy subset" used for the main American Gut manuscript 
(in preparation) is defined. The definition of this healthy subset may not be appropriate 
for all analyses (i.e., it might be too restrictive, or not restrictive enough), so you 
are encouraged to define your subsets accordingly to the questions you are asking from 
the American Gut dataset.

We filtered the cohort to conserve samples based on the following criteria: adults 
20-69 years of age with BMIs ranging between 18.5 and 30, and no self-reported history 
of inflammatory bowel disease, diabetes, or antibiotic use in the past year.