It is thought that most cases of gastro-oesophageal reflux disease (GORD) are caused by a problem with the lower oesophageal sphincter (LOS) muscle. The LOS is located at the bottom of the oesophagus (gullet), the tube that runs from the back of the throat to the stomach.
The LOS works in a similar way to a valve. It opens to let food into your stomach, and it closes to prevent acid leaking back up into your oesophagus.
However, in people with GORD, the LOS can become weakened, which allows stomach acid to pass back into the oesophagus. This causes symptoms of heartburn, such as a burning pain or a feeling of discomfort in your stomach and chest.
Exactly what causes the LOS to become weakened is not always clear, but a number of risk factors have been identified.
These are outlined below.
- being overweight or obese – this can place an increased pressure on your stomach, which in turn can weaken the LOS
- having a diet high in fatty foods – the stomach takes longer to dispose of stomach acids after digesting a fatty meal
- consuming tobacco, alcohol, coffee, or chocolate – it has been suggested that these four substances may relax the LOS
- being pregnant – changes in hormone levels during pregnancy can weaken the LOS and increase pressure on your stomach
- having a hiatus hernia – a hiatus hernia is where part of your stomach pushes up through your diaphragm (the sheet of muscle used for breathing)
There is also a condition called gastroparesis, where the stomach takes longer to dispose of stomach acid. The excess acid can push up through the LOS.
Gastroparesis is common in people who have diabetes, because high blood sugar levels can damage the nerves that control the stomach.
There are a number of medications that can relax the LOS, leading to the symptoms of GORD.
Last updated: 09 March 2015
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