Background: While coeliac disease is clearly induced by dietary gluten ingestion in genetically susceptible individuals, other environmental factors may influence the onset of disease. Two studies have suggested that cigarette smoking has a protective role, but a third has not.
Methods: We examined the relationship between cigarette smoking and coeliac disease in individuals with coeliac disease diagnosed in adulthood from two large population-based disease registers and age and sex-matched controls from local general practitioner lists. Participants were mailed a three-page lifestyle and general health questionnaire. Smoking habits of coeliacs were compared with controls and with habits reported in the Health Survey for England 1995.
Results: An inverse association between current smoking and adult coeliac disease was identified (odds ratio: 0.77 (95% CI 0.56-1.06)) and remained when comparing ever smoked versus never smoked (odds ratio: 0.83 (0.68-1.00)). When the smoking habits of the coeliacs were compared with the national figures, the number of coeliacs who currently smoked was 40% lower than expected (smoking ratio 0.60, 0.46-0.78). This inverse association was accounted for by the behaviour of the 35-54-year age group (odds ratio for ever smoked 0.67 (0.51-0.89)). There was no association with having ever smoked in the younger age group (odds ratio: 1.44 (0.75-2.78)) or the older group (odds ratio: 0.92 (0.67-1.26)).
Conclusions: There was an inverse association between adult coeliac disease and cigarette smoking which was accounted for by middle-aged coeliacs having never smoked. These results are consistent with an age-dependent interaction between cigarette smoking and the other environmental factors implicated in coeliac disease, including gluten.