The protocol for the microbiome measurements was explained in detail earlier [8 (link)]. Briefly, this process included three steps: sample processing, DNA extraction and DNA sequencing. Sample processing: Participants were provided a stool collection kit (Commode Specimen Collection System, Fisher Scientific, Pittsburgh, PA, United States) to collect a stool sample within 24 h prior to their study visit. Aliquots were made in 36 h from the time of sample collection and stored at −80°C. DNA extraction: DNA isolation was performed with the use of the PSP Spin Stool DNA Plus Kit (Stratec, Germany). Barcoded primers (Eurofins Genomics, Louisville, KY, United States) were used to amplify the 16S rRNA gene section. DNA sequencing: After being cleaned (MinElute PCR Purification kit, Qiagen, Germantown, MD, United States), DNA libraries were pooled and subsequently sequenced on the MiSeq platform, 300 bp paired-end reads, at an average depth of 158,000 reads/sample (Illumina Inc., San Diego, CA, United States) in two batches; at the University of Pennsylvania Next-Generation Sequencing Center (UPenn NGSC, N = 107) and the Vanderbilt University Technologies for Advanced Genomics (VANTAGE) Core (N = 29).