Saturday June 15, 2013 (foodconsumer.org) -- A new study in Infection and Immunity confirms that a high salt diet can increase the risk of stomach cancer or gastric cancer in individuals who are infected with Helicobacter pylori.

Jennifer A. Gaddy from Vanderbilt University School of Medicine, Nashville, Tennessee, USA and colleagues conducted the study and found 100% of Mongolian gerbils infected with H. pylori fed a high salt diet developed gastric cancer.

It has been known that men and women who carry Helicobacter pylori chronically or persistently are at higher risk for gastric cancer.  The risk is particularly higher when the carrier also uses a high salt diet.  It is also known that high salt diet can trigger the releasing of a bacterial oncoprotein now known as CagA, promoting the gastric carcinogenesis.

For the study, the researchers exposed Monglian gerbils with wild-type cagA+ H. pylori strain or an isogenic cagA mutant strain, which was unable to produce oncoprotein CagA, and kept the animals on a regular diet or a high-salt diet. 

At 4 months after infection, gastric cancer was detected in 100% of the animals infected with the wild-type bacteria, that was able to produce CagA and also on the high salt diet, 58% of  animals infected with wild-type H. pylori and kept on the regular-diet, and none of the animals infected with the cagA mutant strain, which was unable to produce CagA.

Additionally the researchers also found "Among animals infected with the WT strain, those fed a high-salt diet had more severe gastric inflammation, higher gastric pH, increased parietal cell loss, increased gastric expression of interleukin 1β (IL-1β), and decreased gastric expression of hepcidin and hydrogen potassium ATPase (H,K-ATPase) compared to those on a regular diet." 

Animals infected with the cagA mutant strain suffer low levels of gastric inflammation and did not develop hypochlorhydria in which individuals can't produce gastric acid or only low levels of gastric acid. 

The study suggests that individuals who carry H. pylori should avoid using a high salt diet to reduce their risk of developing gastric cancer.  People in Asia are more likely to carry H. pylori and they are at a higher risk for gastric cancer, compared with people in other regions.

H. Pylori may not be the only cause for  gastric cancer.  Another study published in the American Journal of Clinical Nutrition suggests that smoking, gastric atrophy, and insufficient intake of fruits can all increase the risk of gastric cancer. (reporting by David Liu, PHD)