Scientists believe a common liver disease may be caused by the production of alcohol within the body.
Fatty liver disorder is thought to affect around one in four people in developed countries. It particularly affects obese people.
The condition is currently untreatable, and one in ten sufferers go on to develop cirrhosis of the liver, which in turn increases the risk that cancer will develop in the organ.The damage caused to the liver is identical to that associated with heavy alcohol abuse. However, in this case the problem was not alcholism, but the production of alcohol by an internal distillery within the body itself.
Dr Diehl thinks undigested food might stay in the intestines of obese people for longer. This could allow normally harmless gut bacteria to ferment the food and produce alcohol, which would then cause fat to form in the liver.
Dr Diehl's team tested the theory on mice genetically engineered to be obese. The mice were fed on a diet that did not contain alcohol, and breath samples were taken as they aged. Obesity-related fatty liver disorder usually develops in older animals and people. The scientists found that older obese mice produced roughly five times as much ethanol as older lean mice, and all the obese mice developed fatty livers.
Dr Diehl said: "We think that obesity changes the way the intestines propel their contents from one end to the other. "This means there are static periods when ethanol alcohol is overproduced." The research is published in the journal Gastroenterology.