VITAL
POINTERS
Smoking and Your Digestive
System
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. How does smoking affect
the digestive system of all these people?
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. Normally, a muscular valve at the lower
end of the esophagus, the lower esophageal sphincter (LES),
keeps the acid solution in the stomach and out of the esophagus.
Smoking decreases the strength of the esophageal valve, thereby
allowing stomach juice to reflux, or flow backward into the
esophagus.
Smoking also seems to promote the movement of bile salts from
the intestine to the stomach, which makes the stomach juice
more harmful. Finally, smoking may directly injure the esophagus,
making it less able to resist further damage from refluxed
material.
Peptic Ulcer
A peptic ulcer is an open sore in the lining of
the stomach or duodenum, the first part of the small intestine.
The exact cause of ulcers is not known. A relationship between
smoking cigarettes and ulcers, especially duodenal ulcers,
does exist. The 1989 Surgeon General's report stated that
ulcers are more likely to occur, less likely to heal, and
more likely to cause death in smokers than in nonsmokers.
Why is this so? Doctors are not really sure, but smoking
does seem to be one of several factors that work together
to promote the formation of ulcers.
For example, some research suggests that smoking might increase
a person's risk of infection with the bacterium Helicobacter
pylori (H. pylori). Most peptic ulcers are caused by this
bacterium.
Stomach acid is also important in producing ulcers. Normally,
most of this acid is buffered by the food we eat. Most of
the unbuffered acid that enters the duodenum is quickly neutralized
by sodium bicarbonate, a naturally occurring alkali produced
by the pancreas. Some studies show that smoking reduces the
bicarbonate produced by the pancreas, interfering with the
neutralization of acid in the duodenum. Other studies suggest
that chronic cigarette smoking may increase the amount of
acid secreted by the stomach.
Whatever causes the link between smoking and ulcers, two points
have been repeatedly demonstrated: People who smoke are more
likely to develop an ulcer, especially a duodenal ulcer, and
ulcers are less likely to heal quickly among smokers in response
to otherwise effective treatment. This research tracing the
relationship between smoking and ulcers strongly suggests
that a person with an ulcer should stop smoking.
Liver Disease
The liver is an important organ
that has many tasks. Among other things, the liver is responsible
for processing drugs, alcohol, and other toxins to remove
them from the body. There is evidence that smoking alters
the ability of the liver to handle these substances. In some
cases, this may influence the dose of medication necessary
to treat an illness. Some research also suggests that smoking
can aggravate the course of liver disease caused by excessive
alcohol intake.
Crohn's
Disease
Crohn's disease causes inflammation
deep in the lining of the intestine. The disease, which causes
pain and diarrhea, usually affects the small intestine, but
it can occur anywhere in the digestive tract. Research shows
that current and former smokers have a higher risk of developing
Crohn's disease than nonsmokers do.
Among people with the disease, smoking is associated with
a higher rate of relapse, repeat surgery, and immunosuppressive
treatment. In all areas, the risk for women, whether current
or former smokers, is slightly higher than for men. Why smoking
increases the risk of Crohn's disease is unknown, but some
theories suggest that smoking might lower the intestine's
defenses, decrease blood flow to the intestines, or cause
immune system changes that result in inflammation.
Gallstones
Several studies suggest that
smoking may increase the risk of developing gallstones and
that the risk may be higher for women. However, research results
on this topic are not consistent, and more study is needed.
Can
the Damage be Reversed?
Some of the effects of smoking
on the digestive system appear to be of short duration. For
example, the effect of smoking on bicarbonate production by
the pancreas does not appear to last. Within a half-hour after
smoking, the production of bicarbonate returns to normal.
The effects of smoking on how the liver handles drugs also
disappear when a person stops smoking. However, people who
no longer smoke still remain at risk for Crohn's disease.
Clearly, this question needs more study.
|
