Salt reduction may cut stomach ulcer risk
pylori bacteria in the stomach, said to be the cause of
millions of cases of gastritis and peptic ulcer disease each year,
says a new study that may have added implications for salt
reduction in foods.
The new study, presented yesterday at the 107th General Meeting of the American Society for Microbiology in Toronto, indicates that high concentrations of salt in the stomach appear to induce gene activity in the bacterium, increasing both its virulence and the likelihood of an infected person developing a severe gastric disease. H. pylori is the only bacteria that can survive in the acidic environment of the stomach and it is known to cause peptic ulcers and gastritis. Infection with H. pylori also causes gastritis, and infected persons are said to have a two to six-fold increased risk of developing mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric cancer compared with uninfected counterparts. "Apparently the stomach pathogen H. pylori closely monitors the diets of those people whom it infects," said researcher Hanan Gancz, from the Uniformed Services University of the Health Sciences in Bethesda, Maryland. "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." Salt is of course a vital nutrient and is necessary for the body to function, but salt reduction campaigners such as the Consensus Action on Salt and Health (CASH) consider the average daily salt consumption in the western world, between 10 and 12g, far too high. Numerous scientists are convinced that high salt intake is responsible for increasing blood pressure (hypertension), a major risk factor for cardiovascular disease. CVD causes almost 50 per cent of deaths in Europe, and reported to cost the EU economy an estimated €169bn ($202bn) per year. The new research, sponsored by the U.S. National Institutes of Health, appears to indicate other undesirable health conditions as a result of a high-salt diet. Gancz and co-workers investigated whether a high concentration of salt had a direct effect on both the growth and gene expression of the bacterium. "We noted that H. pylori growth rate shows a sharp decline at high salt concentrations. Moreover, bacterial cells exposed to increased salt exhibited striking morphological changes: cells became elongated and formed long chains," said Gancz. "We conclude that H. pylori exposed to high levels of salt in vitro exhibit a defect in cell division." The researchers also reported that the copying (transcription) of two genes associated with bacterium virulence was increased during high-salt conditions. "The altered expression patterns of some virulence genes may partially explain the increased disease risk that is associated with a high salt diet in H. pylori infected individuals," said Gancz. The pressure has been mounting on food manufacturers to reduce the salt content of their foods. The UK's food standards agency (FSA) recommendation of six grams of salt per day for the general population is understood to be more a realistic target for the next five years than the ideal healthy limit. In the UK, Ireland and the USA, over 80 per cent of salt intake comes from processed food, with 20 per cent of salt intake coming from meat and meat products, and about 35 per cent from cereal and cereal products. Salt remains a vitally important compound in food manufacturing, in terms of taste and preservation. In processed meat products, for example, salt is involved in activating proteins to increase water-binding activity, improves the binding and textural properties of proteins, helps with the formation of stable batters with fat, and also extends shelf-life with its anti-microbacterial effects.