摘要Tobacco use increases the risk of many diseases,such as lung cancer,chronic obstructive pulmonary disease,and coronary heart disease.Smoking is the most preventable cause of death,responsible for over 6 million deaths world-wide each year.The average life expectancy of smokers is re-duced by 10 years compared to those who never smoke[1].Nicotine accumulates in the upper gastrointestinal tract dur-ing smoking,which may lead to pathological damage.Smoking is positively associated with the development of non-alcoholic fatty liver disease(NAFLD).However,the underly-ing molecular mechanism for the correlation of nicotine with NAFLD is still unknown.Reporting in Nature,CHEN and co-workers found that nicotine accumulated in the intestine dur-ing smoking accelerated the occurrence of NAFLD.Moreover,this study demonstrated that the human gut bac-terium Bacteroides xylanisolvens(B.xylanisolvens)effect-ively degrades ileal nicotine[2].