This fact can have serious consequences because it is the digestive system that converts foods into the nutrients the body needs to live. Current estimates indicate that about one-third of all adults smoke. And, while adult men seem to be smoking less, women and teenagers of both sexes seem to be smoking more. Harmful Effects Smoking has been shown to have harmful effects on all parts of the digestive system, contributing to such common disorders as heartburn and peptic ulcers. It also increases the risk of Crohn's disease and possibly gallstones.
Smoking seems to affect the liver, too, by changing the way it handles drugs and alcohol.
In fact, there seems to be enough evidence to stop smoking solely on the basis of digestive distress. Heartburn Heartburn is common among Americans. More than 60 million Americans have heartburn at least once a month, and about 15 million have it daily. Heartburn happens when acidic juices from the stomach splash into the esophagus. Smoking decreases the strength of the esophageal valve, thereby allowing stomach juice to reflux, or flow backward into the esophagus.