Peptic ulcers: what causes them?
Peptic ulcers occur in the stomach (gastric ulcers) and the first part of the small intestine (duodenal ulcers). They result from an imbalance between factors that help maintain the protective lining of the stomach and duodenum and factors that can lead to damage and erosion of this mucosal lining.
Most peptic ulcers are caused by either infection with Helicobacter pylori or regular use of medicines called non-steroidal anti-inflammatory drugs (NSAIDS), including aspirin. Almost all duodenal ulcers are associated with H. pylori infection, while stomach ulcers are commonly caused by NSAID use.
In the past it was believed that peptic ulcers were caused by stress, poor dietary habits (including eating too much rich, fatty or spicy foods), alcohol and caffeine. It’s now known that these things don’t cause peptic ulcers, but they may increase the amount of acid made in your stomach and make your symptoms worse if you do have an ulcer.
H. pylori infection
Helicobacter pylori (H. pylori) is a corkscrew-shaped bacterium that can infect the inner lining of the stomach. H. pylori was discovered by Australian researchers in a huge breakthrough that has revolutionised the understanding and treatment of ulcers worldwide.
Most types of bacteria cannot live in the stomach because it is a very acidic environment. But H. pylori can live there because it makes an enzyme called urease. Urease produces neutralising agents which protect the H. pylori from the strong acid of the stomach.
H. pylori infection is common, especially in developing countries. Infection rates are lower for Western countries. About 30 per cent of adults in Australia are thought to be infected.
How do you get H. pylori infection?
Most people become infected during childhood. H. Pylori can be passed from person to person through direct contact with either saliva or faeces. Although doctors are not certain, they suspect the bacteria may be spread through sharing food, cutlery and utensils for eating and drinking with infected people.
H. pylori has been detected in the saliva of infected people, leading scientists to think that it may also be spread by mouth-to-mouth contact, such as kissing. Inadequate hand washing after going to the toilet and untreated water are other ways that the bacteria can be spread.
Most people infected with H. pylori do not get peptic ulcers (but many do get gastritis - inflammation of the stomach). Why some infected people develop ulcers while others do not is not entirely clear. Whether an infected person develops an ulcer or not may depend on their personal characteristics, environmental or hereditary factors.
How does H. pylori cause ulcers?
H. pylori can penetrate and live in the lining of the stomach and duodenum, where it causes inflammation. Persistent inflammation interferes with and changes the protective lining of the stomach and duodenum. This can lead to increased acid production and erosion of the lining, which may form an ulcer.
NSAIDS and stomach ulcers
Long-term or frequent use of medicines called non-steroidal anti-inflammatory drugs (NSAIDs) - such as aspirin, ibuprofen and naproxen - can cause stomach ulcers. Up to 30 per cent of people using NSAIDs develop a peptic ulcer, but many don’t know it because they don’t have any symptoms.
The risk of developing an ulcer depends on the type of NSAID used and the dose. Some NSAIDs are more likely to cause ulcers than others, and higher doses are associated with a greater risk.
In addition, among people who use NSAIDs, some are at higher risk of developing peptic ulcers than others. NSAID users who are infected with H.pylori have a greatly increased risk of developing a peptic ulcer and an increased risk of bleeding.
NSAID-induced peptic ulcers are more common in:
- older people (those aged 70 years and older);
- those taking certain other medicines (such as corticosteroids or some medicines for osteoporosis) at the same time;
- people who have had peptic ulcers in the past;
- people who drink alcohol; and
- those who smoke.
How do NSAIDs cause peptic ulcers?
Taking NSAIDs can make the stomach lining more vulnerable to the potentially damaging effects of stomach acid, especially in older people or people taking them for a long time. That’s because NSAIDs inhibit substances called prostaglandins that help protect the mucosal lining of the stomach.
Rare causes of peptic ulcers
Zollinger-Ellison syndrome is a rare cause of peptic ulcers. People with this condition have a tumour (or tumours), usually in their duodenum or pancreas, that releases a hormone called gastrin. This hormone causes the stomach to make more acid than usual, and the excess acid can cause peptic ulcers to develop.
Peptic ulcers can also sometimes develop in people who are very unwell (usually those being treated in intensive care units in hospitals for problems such as severe burns). These so-called stress ulcers are actually caused by a lack of blood flow to the stomach. People who are seriously ill are usually given acid-suppressing medicines to try to prevent this type of peptic ulcer developing.
Some infections and medicines other than NSAIDs can also rarely cause peptic ulcers. In other cases, no obvious cause can be found.
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