Most cases of gastro-oesophageal reflux disease (GORD) are caused by a problem with the lower oesophageal sphincter (LOS). The LOS is the muscle around at the bottom of the oesophagus (food pipe).
The LOS acts like a valve. It opens to let food and fluids fall into the stomach, and closes to prevent acid leaking out of the stomach and back up into the oesophagus. The LOS can become weakened and may not close properly. This allows acid to leak up into the oesophagus causing symptoms such as heartburn.
It’s not always clear why the LOS becomes weakened, but it’s more likely to happen in people:
- who are overweight or obese
- who consume lots of fatty foods, because the stomach takes longer to dispose of stomach acids after digesting a fatty meal
- who consume substances which may relax the LOS such as tobacco, alcohol, coffee or chocolate
- who are pregnant, due to changes in hormone levels which can relax the LOS, as well as the increased pressure on the stomach during pregnancy
- who have connective tissue disorders
- with a hiatus hernia, where part of your stomach pushes up through your diaphragm (the sheet of muscle which separates the abdomen from the chest)
- with a condition called gastroparesis (fairly common in people with diabetes) where the stomach takes longer to dispose of stomach acid
- who are feeling stressed
- who smoke
- who take certain medicines, such as aspirin
Learn more here about the development and quality assurance of healthdirect content.
Last reviewed: September 2018