The bug that causes stomach ulcers may be more likely to cause disease when exposed to high concentrations of salt, a US team of researchers has said.
Two genes associated with the potency of Helicobacter pylori became more active if a lot of salt is present.
Presenting the results at the American Society for Microbiology conference, the researchers said research had shown salt was linked to gastric cancer.
Experts said the findings suggested how salt and H. Pylori may interact.
H. pylori lives in the stomach, and accounts for up to 90% of duodenal ulcers and up to 80% of gastric ulcers.
The bacterium may also increase the risk of gastric cancer.
Many people carry the bacterium without experiencing any symptoms.
And some of those who are affected suffer far less severe symptoms than others.
Study leader Dr Hanan Gancz and colleagues said it was known that people who ate a high-salt diet had an increased risk of gastric cancer but no one had looked specifically at the effects of salt on H. pylori itself.
They measured the growth and gene expression of the H. pylori in the laboratory and found that in the presence of high concentrations of salt the growth rate of the bacterium dropped.
However, it did change shape and formed long chains.
At the same time, two genes associated with the virulence of the bacterium, were expressed more readily.
Dr Gancz, of the Uniformed Services University of the Health Sciences in Bethesda, Maryland, said: “Epidemiological evidence has long implied that there is a connection between H. pylori and the composition of the human diet. This is especially true for diets rich in salt.”
He added: “Apparently H. pylori closely monitors the diets of those people whom it infects.
“We think that when there are high levels of salt in the stomach environment, H. pylori over produces these factors which enable it to survive, which in the long term increases the risk of illness,” he said.
Too much salt in the diet also causes high blood pressure and is a major cause of heart attacks and stroke.
Dr Perminder Phull, consultant in gastroenterology at Aberdeen Royal Infirmary, said diet used to be a major factor in how people with ulcers were treated but advances in treatment mean that is no longer an issue.
“But there is research that shows that a high salt diet increases the risk of gastric cancer and this might explain the mechanism between salt and H. pylori infection.”