Gastro-oesophageal reflux: what causes it?
When you swallow, food is passed down the oesophagus (the tube that passes food and liquid from your mouth down to your stomach) by waves of muscle contractions and is then passed into the stomach.
The entry of food from the lower end of the oesophagus into the stomach is controlled by a ‘valve’ called a sphincter. This particular sphincter is known as the lower oesophageal sphincter. It is a band of muscle that opens to allow the food to pass from the oesophagus down into your stomach and then closes again to prevent the acidic stomach contents from coming back up. It should normally only allow upward flow when you are belching or vomiting.
THE OESOPHAGUS AND LOWER OESOPHAGEAL SPHINCTER
In people who suffer from gastro-oesophageal reflux (often just called reflux) the lower oesophageal sphincter does not function properly. The sphincter allows the acidic contents of the stomach to escape and leak into the oesophagus. Because of its acidic nature this cocktail of partially digested food and acid is very irritating to the lining of the oesophagus and to the throat.
The most common reasons that the lower oesophageal sphincter does not function properly are a weakness of the lower oesophageal sphincter and the presence of a hiatus hernia.
Weakness of the lower oesophageal sphincter
In some people the lower oesophageal sphincter (LES) muscle is weak or relaxes when it shouldn’t and lets the stomach contents flow up into the oesophagus.
Hiatus hernia
A hiatus hernia is when the upper part of the stomach slides up through the gap in the diaphragm into the chest cavity. The diaphragm is the muscle that separates the chest from the stomach. Normally, the gap is only wide enough to allow the oesophagus through it.
The hiatus hernia reduces the efficiency of the LES and can result in reflux. Also, in normal circumstances, the opening in the diaphragm is thought to act as another sphincter around the lower end of the oesophagus and if the opening is too big it will not have this capacity.
Factors that make reflux worse
Food and drinks
Some foods and drinks are known to worsen the symptoms of reflux. These include:
- fried or fatty foods;
- spicy foods;
- onions;
- peppermint or mints;
- chocolate;
- tomato-based foods;
- drinks such as coffee, tea, cola; and
- citrus fruits or drinks.
Milk can also be a problem. If you are drinking it to help the pain, it can actually make things worse, by causing the stomach to secrete more acid.
Cigarettes and alcohol
The lower oesophageal sphincter is known to be relaxed by cigarette smoking and alcohol consumption, making reflux worse.
Medications
Some types of medications can increase the occurrence of reflux and these include the following.
- Non-steroidal anti-inflammatory drugs (NSAIDs). These include drugs such as aspirin and ibuprofen.
- Anticholinergics (these medications can increase the tendency of the lower oesophageal sphincter to relax). Elderly people are particularly sensitive to these drugs. Some examples are: Cogentin (benztropine), Buscopan (hyoscine), Ditropan (oxybutynin), and Pro-Banthine (propantheline).
- Theophylline, e.g. Nuelin SR (rarely used these days in the treatment of asthma).
- Calcium channel blockers (these medications are used in the treatment of high blood pressure and angina).
Check with your doctor if you take these types of medications and seem to be having regular episodes of reflux. Do not discontinue your medications unless instructed by your doctor.
Obesity and pregnancy
Being overweight or obese or being pregnant can increase the pressure on the abdomen and also be a cause of the stomach contents refluxing up into the oesophagus.
Bending and straining
The same mechanism explains why you may experience reflux when you bend over at the waist. Many people who suffer reflux find that lying down can also worsen reflux symptoms. Straining can increase the pressure in the abdomen and thus cause hiatus hernia.
Large meals
Overeating or eating just before going to bed can worsen reflux symptoms.
Last Reviewed: 25 November 2009
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