Meat can 'increase gastro susceptibility'
Eating red meat and unpasteurised dairy products could make people more susceptible to bacteria that cause severe gastroenteritis and, in rare cases, fatal kidney failure, Australian research suggests.
Shiga toxigenic Escherichia coli bacteria can cause bloody diarrhoea and the potentially fatal haemolytic uraemic syndrome (HUS), the commonest cause of acute kidney failure in children.
Beddoe and colleagues studied how a toxin secreted by the E. coli strain causes HUS by going from the stomach into cells and the bloodstream.
They found the toxin is transported inside human cells by binding to a specific sugar, called N-glycolylneuraminic acid-containing saccharide, that is contained in foods.
"The toxin sticks to the sugar to get inside cells," Beddoe says.
"This uncovered the first example of bacterium causing disease in humans by targeting a molecule which is incorporated into our bodies through what we eat."
The sugar is abundant in red meats, especially beef, lamb and pork, and unpasteurised cow's milk.
Ironically these are also the foods most commonly contaminated with the E. coli strain.
When eaten, the sugar is stored in human tissue, stomach or kidney cells.
"Thus through regular dietary intake of red meats and milk, humans may presensitise their tissues to a key virulence factor of a major pathogen that occurs sporadically in the same foods," the researchers write.
Beddoe says processed meats, especially hamburgers are a main culprit, but also salami and sausages, because the E. coli bacteria may be mixed throughout and sealed inside.
If the meat in these is not cooked properly it may cause disease unlike steak where any E. coli is on the outside and is cooked off.
"People can reduce their risk by ensuring they cook meat such as hamburgers well, have good food handling practices and eat pasteurised dairy products," says Beddoe.
The E. coli strain causes about three HUS outbreaks in Australia a year, with 5% of cases being fatal.
Thirteen years ago, 23 children developed HUS, linked to mettwurst sausage from South Australia. One child who died and 14 suffered major health complications such as kidney damage, stroke and convulsions.
Other HUS outbreaks in Australia have been linked to eating meat pizza and petting zoo animals.