[Smoking and alimentary diseases].

Tobacco smoking directly or hematogenously acts on digestive organ and induces benign and malignant alimentary diseases. Nicotine, nitrosamines, and polycyclic aromatic hydrocarbons included in tobacco smoke are major causative agents of tobacco smoking-related alimentary diseases. These agents have harmful effects on digestive organ through compromised blood circulation, impaired neural regulation, and cell dysfunction. These malfunctions cause tissue destruction, such as chronic inflammation and ulcer formation. Besides forming DNA adducts, they also act on endogenous signal transduction, leading to gene mutation and abnormal cell death and growth. Interestingly, in inflammatory diseases, smoking improves symptoms of ulcerative colitis, while it worsens the condition of Crohn diseases. Smoking is also involved in lately increasing Barrette's esophagus. Future studies are needed.