Overview of gut microbiota composition and associated host factors. A) Graphical summary of the cohort and overview of variables (N = number of variables collected, n = sample size). Background in the map of China is colored according to region classification. The red curve indicates the boundary of two area in this study. The red straight line indicates Hu Huanyong line of China's population boundary. B) The relative abundances of the top five phylum‐level microbiota among individuals (n = 3,224). C) The relative abundances of the top ten genera. D) The effect sizes of host factors significantly associated with gut microbial variations were evaluated by PERMANOVA (Adonis) filtered based on FDR < 0.05. The bars are colored according to metadata categories. HLJ, Heilongjiang (n = 235); LN, Liaoning (n = 141); BJ, Beijing (n = 115); SD, Shandong (n = 131); JS, Jiangsu (n = 146); SH, Shanghai (n = 140); ZJ, Zhejinag (n = 142); SX, Shaanxi (n = 140); HeN, Henan (n = 390); HB, Hubei (n = 134); HN, Hunan (n = 457); CQ (n = 148), Chongqing; GZ, Guizhou (n = 342); YN, Yunnan (n = 130); GX, Guangxi (n = 433).