Smoking and the Digestive System

The harms of smoking to the lungs and the heart are well known. But the nicotine and the many harmful chemicals in tobacco smoke can also affect almost every part of the digestive system.

Smoking can make it easier for various diseases to develop or to get worse — from reflux to gastric ulcer, from Crohn’s disease to pancreatitis. It also increases the risk of certain digestive cancers, including cancers of the oesophagus, the stomach, the pancreas and the large bowel.

For this reason stopping smoking matters not only for the health of the lungs and the heart but for the health of the digestive system too.

How does smoking affect the digestive system?

The substances in tobacco smoke do not only come into contact with the mouth and the lungs. Substances passing into the blood spread throughout the body.

Smoking can:

• Disturb the natural defence mechanisms of the digestive system,
• Delay the healing of tissue,
• Adversely affect the circulation of blood in some regions,
• Disturb the protective mechanisms of the stomach and the oesophagus,
• Alter immune and inflammatory mechanisms,
• Increase exposure to certain carcinogenic substances.

The outcome of these effects varies from person to person, and the risk generally rises as the amount and the duration of smoking increase.

Smoking and reflux

Smoking is one of the factors that can make gastro-oesophageal reflux disease (GORD) easier to develop.

At the lower end of the oesophagus there is a muscular structure called the lower oesophageal sphincter, which helps to prevent the contents of the stomach escaping upwards.

Smoking can adversely affect this protective mechanism and make it easier for the contents of the stomach to pass back into the oesophagus.

The result may be an increase in reflux complaints such as:

• Burning in the chest,
• Bitter or sour fluid coming into the mouth,
• Belching,
• Burning or discomfort in the throat.

Stopping smoking is one of the important lifestyle parts of the treatment of reflux.

Smoking, Barrett’s oesophagus and cancer of the oesophagus

Long-standing reflux can in some people lead to the change in the lower part of the oesophagus called Barrett’s oesophagus.

Smoking matters particularly in people with Barrett’s oesophagus, and is an additional risk factor for cancer of the oesophagus.

Smoking increases the risk of developing both squamous cell cancer of the oesophagus and adenocarcinoma of the oesophagus.

Stopping smoking is therefore especially important for patients who have reflux or Barrett’s oesophagus.

Does smoking harm the stomach?

Yes.

The stomach has natural defence mechanisms that protect it from its own acid. Smoking can adversely affect these protective mechanisms and reduce the resistance of the lining of the stomach and duodenum to damage.

Smoking matters particularly for peptic ulcer disease.

Smoking can:

• Increase the risk of an ulcer developing,
• Delay the healing of an ulcer,
• Make it easier for an ulcer to recur,
• Increase the risk of complications from an ulcer.

Where other risk factors are also present — Helicobacter pylori infection or the use of painkillers (NSAIDs) in particular — the adverse effects of smoking can become still more important.

Does smoking increase the risk of stomach cancer?

Yes.

Smoking is one of the known risk factors for stomach cancer.

The risk may be related to the amount and the duration of use. With stopping, the risk begins to fall over time.

It should not be forgotten that other factors besides smoking play a part in the development of stomach cancer — H. pylori infection, family history, certain diseases of the stomach, and dietary habits.

Does smoking affect Crohn’s disease?

Yes, and this association is particularly important.

Smoking can increase the risk of developing Crohn’s disease and can cause existing disease to run a more severe course.

In patients with Crohn’s disease who smoke:

• The disease may be more active,
• Flare-ups may be more frequent,
• The need for medicines may increase,
• The need for surgery may increase,
• The risk of the disease reappearing after an operation may be higher.

For this reason, stopping smoking is an important part of treatment in Crohn’s disease.

Is it the same in ulcerative colitis?

There is an interesting situation here, and one that is sometimes misunderstood.

The relationship between smoking and ulcerative colitis differs from that in Crohn’s disease. Epidemiological studies have observed that active smoking is inversely associated with the development of ulcerative colitis, and that in some patients the disease can appear after they give up smoking.

But the conclusion:

“a person with ulcerative colitis should smoke”

must certainly not be drawn from this.

Because of the many serious harms of smoking — cancer, cardiovascular disease and lung disease chief among them — smoking is not recommended as a treatment for ulcerative colitis.

Does smoking affect the pancreas?

Yes.

Smoking is an important risk factor for diseases of the pancreas as well.

It is associated in particular with:

• Acute pancreatitis,
• Chronic pancreatitis,
• Pancreatic cancer.

Using tobacco and alcohol together can increase the risk still further, for chronic pancreatitis in particular.

For a person with chronic pancreatitis, continuing to smoke can make the progression of the disease and the development of complications easier.

Does smoking increase the risk of pancreatic cancer?

Yes. Smoking is one of the most important modifiable risk factors for pancreatic cancer.

A proportion of cases of pancreatic cancer are thought to be related to smoking.

The risk can rise with the duration and the amount of smoking. After stopping, it begins to fall over time.

It therefore matters particularly that people with chronic pancreatitis, or with other risk factors for pancreatic disease, do not smoke.

Does smoking affect the liver?

Smoking is not usually the first cause that comes to mind in liver disease, but it does have adverse effects on the liver too.

Smoking can:

• Increase oxidative stress,
• Affect inflammation in the liver,
• Contribute to the development of fibrosis,
• Adversely affect the course of certain chronic liver diseases.

The additional risk that smoking poses becomes important particularly in people who already have another liver disease.

Does smoking increase the risk of liver cancer?

Yes.

Smoking is associated with an increased risk of hepatocellular carcinoma (liver cancer).

In people with other risk factors such as hepatitis B, hepatitis C, cirrhosis and excessive alcohol, adding smoking can increase the total risk further still.

Is smoking associated with bowel cancer?

Yes.

Long-standing smoking is associated with an increased risk of colorectal adenomas (polyps) and of colorectal cancer.

Many factors play a part in the development of bowel cancer — age, family history, genetic characteristics, weight, physical activity and diet. Smoking is one of the modifiable risk factors among them.

For this reason, stopping smoking does not take the place of regular bowel cancer screening at the appropriate age and risk group; both matter together.

Does smoking increase digestive cancers?

Smoking is not associated with lung cancer alone.

Smoking is associated in particular with an increased risk of:

• Cancers of the mouth and throat,
• Cancer of the oesophagus,
• Stomach cancer,
• Pancreatic cancer,
• Liver cancer,
• Colorectal cancer.

The degree of risk varies with the organ, with the duration and amount of smoking, and with the other risk factors the person has.

Are electronic cigarettes safer?

It cannot be said that electronic cigarettes are harmless for the digestive system.

Electronic cigarettes can cause exposure to nicotine and to various chemical substances. Although the long-term effects of conventional cigarettes on the digestive system are much better known, information about the long-term digestive effects of electronic cigarettes is still developing.

For this reason it is not right to accept that “electronic cigarettes are safe for the digestive system”.

What happens when you stop smoking?

The benefit of stopping smoking is not only preventing diseases that might appear in the future.

Over time after stopping:

• Reflux complaints may lessen,
• The healing of an ulcer may become easier,
• The course of Crohn’s disease may be affected favourably,
• The risk of further damage to the pancreas and other organs may fall,
• The risk of some digestive cancers may fall over time.

However long a person has smoked, there is a benefit to health in stopping.

The important message

Smoking can affect not only the lungs but almost every part of the digestive system.

It can increase the risk of reflux and of cancer in the oesophagus; it can adversely affect ulcer disease in the stomach and the duodenum; it can cause Crohn’s disease to run a more severe course; it is associated with pancreatitis; and it can increase the risk of various cancers, including cancers of the pancreas, the stomach, the oesophagus, the liver and the large bowel.

In people with chronic digestive disease in particular, stopping smoking is one of the most important changes a patient can make for their own health, alongside the medical treatment they are given.

There is no safe level of smoking.

This content has been prepared for general information. Assessment and treatment of people with digestive complaints or with a chronic digestive disease should be planned individually by a doctor.