Smoking and diseases of the gastrointestinal system: An epidemiological review with special reference to sex differences

Smoking increases the risk of peptic ulcer disease and death from it. Smoking delays peptic ulcer healing, with or without treatment, and increases the risk of recurrence after healing. The effects of smoking on this disease are similar and equally pervasive in women and men. There is growing evidence that cigarette smokeing is a risk factor for Crohn's disease (CD) in both women and men. However, women smokers appear to be at particular risk of this disease. In studies that examined this risk separately in women and men, at each level of smoking the excess risk in women smokers compared with nonsmokers clearly exceeded the excess risk in men smokers compared with nonsmokers. Smoking also appears to adversely affect the clinical course of CD in both women and men, but more so in women. The possible interaction between smoking and oral contraceptives with regard to the risk of CD deserves further study. There is growing evidence that current smoking protects against ulcerative colitis in both men and women. Although there is some evidence that smoking is a risk factor for gallstones, particularly in women, evidence to support a causal relationship is inadequate. Further studies, controlling for alcohol consumption in the analyses, are needed. Smoking does not appear to be a risk factor for cirrhosis of the liver.