[Smoking and inflammatory bowel diseases].

In a case-control study 142 patients with Crohn's disease, 189 patients with ulcerative colitis and matched community controls were questioned about their smoking habits. When assessed by smoking habits before the onset of disease, patients with Crohn's disease were four times as likely to have been smokers than their matched controls. In contrast, patients with ulcerative colitis were ten times less likely to have been smokers compared with their matched controls. There was no confounding by social class or alcohol intake differences. The contrasting nature of these associations suggests that there might be an aetiological role for smoking in inflammatory bowel disease.