Smoking and the alimentary tract: a review.

Because of inherent and inseparable variables, studies of the effect of smoking on gastric secretion and motility have proved inconclusive. The only firm conclusions to be drawn from the work reviewed are that the prognosis of both gastric and duodenal ulcers is made worse by regular smoking and that the healing and response of gastric ulcers to medical treatment is impaired. The mechanisms through which these effects are produced are unknown. It is not even certain that nicotine is the chief noxious agent in tobacco. Careful statistical and epidemiological studies have yielded such facts as exist and this approach seems the most promising one for future studies.