Always population-based study the effect of smoking on intestinal flora, found that smokers have diversity than non-smokers, an increase in the abundance of pathogenic or opportunistic pathogens and a decrease in the abundance of beneficial bacteria. However, the research for population screening is not rigorous; there may be bias of disease and living habit, etc. In our study, people with chronic diseases and sub-health were excluded, and personal lifestyle information was collected to explore the effects of smoking on intestinal microflora in healthy people, and to eliminate the bias in exercise and diet.
