In describing an instance of intense anger, you might say, as a figure of speech, that bile rose in your throat. But for some people, bile does indeed rise, perhaps not as far as the throat but far enough to cause digestive distress and serious damage to the lining of the stomach and oesophagus.

The symptoms are similar to heartburn, and many sufferers are told they have gastro-oesophageal reflux disease, known as acid reflux.

Yet, treatment with popular remedies for acid reflux, like the acid-suppressing proton-pump inhibitors fails to work or gives only partial relief.

That's because acid reflux is, at most, only part of the problem. The main culprit is bile reflux, a back-up of digestive fluid that is supposed to remain in the small intestine, where it aids the digestion of fats.

Bile is not acid. It is an alkaline fluid, consisting of bile salts, bile pigments, cholesterol and lecithin. It is produced by the liver, stored in the gallbladder and released intermittently into the duodenum, the upper part of the small intestine, when needed to digest fat. (Bile continues to be produced as a digestive aid even after the gallbladder is removed.)

Misdiagnosis of bile reflux and failure to control it can result in serious, sometimes life-threatening problems — stomach ulcers that bleed and Barrett's oesophagus, a possible precursor to oesophageal cancer. Yet misdiagnosis is common, and even when the condition is properly identified, doctors are often fatalistic about its management.

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