Summary - High salt consumption is a risk factor for the development of gastritis, gastric ulcers and gastric adenocarcinoma. If you have a stomach ulcer and your salt consumption is high, reducing the amount of salt you eat might help heal your ulcer, especially in combination with other treatments like antibiotics and Vitamin U. Talk to you doctor about your options.
(For clarification, "peptic ulcer" usually refers to ulcers in either the stomach or the duodenum. A "gastric ulcer" is another name for a stomach ulcer.)
The two most cited risk factors for the development of stomach ulcers are infection with Helicobacter pylori and taking NSAIDs (Mayo Clinic, 2020a). High dietary salt is another risk factor that is lesser known, though it has long been considered a risk factor in the development of stomach cancer (Mayo Clinic, 2020b; Cromer et al, 1949). Stomach ulcers and stomach cancer are two different conditions, and ulcers do not automatically lead to stomach cancer. However, these two conditions result from a similar set of risk factors, include high salt intake. What determines whether you develops ulcers or cancer may lie in genetics, diet, and to a certain extent, luck.
It has been long noted that at times when salt consumption within a population is low, stomach ulcers are rare (Sonnenberg 1986 and references within). For example, prior to the French Revolution, salt was heavily taxed in France as a means of raising crown revenue. Salt consumption was light among the general population. and the incidence of stomach ulcers was low. As salt taxes were repealed, salt consumption especially via its use as a food preservative increased. Salt consumption in the Western world peaked in the early 20th century, declining with the invention of alternative forms of preservation like canning and refrigeration. Throughout this period, mortality due to stomach ulcers rose, peaked, then declined in lockstep with salt use.
Another way to show a relationship between salt intake and stomach ulcer prevalence is to look at these factors in different countries at a given time. Countries in which salt intake is high (e.g. Japan, Portugal, Spain) tend to have higher mortalities from stomach ulcers than those in which salt intake is low (Sonnenberg 1986).
Does this mean your stomach ulcer is caused by eating too much salt? On the one hand, your ulcer is caused by something, and if your diet is heavy in salt, it might be a contributing factor. On the other hand, while the evidence is quite suggestive, it's important to take these findings with a grain of salt (so to speak). If you have a stomach ulcer and eat a lot of salt, reducing dietary salt for a couple of weeks and seeing whether the pain goes away might be worth trying. Even better, talk to your doctor as a combination of reduced salt intake and other treatments might be even more effective.
How does a high-salt diet cause stomach ulcers?
By itself, high salt intake can cause a non-inflammatory atrophic gastritis (Bergin et al, 2003). Concentrated salt strips off the mucous bilayer by inducing edema, increasing the percentage of replicating cells susceptible to mutagenesis, and exposing the underlying epithelial cells to damaging stomach acid (Charnley and Tannenbaum, 1985). The heightened cell turnover especially in combination with mutagens increases the chances of a cancer-causing mutation occurring. Acidic damage reduces production of mucus and acid required for digestion, with chronic damage resulting in low stomach acid (hypochlorhydria) (Cromer et al, 1949) and predisposes to ulcer formation.
Like salt, H. pylori can induce atrophic gastritis in and of itself, while also inducing an inflammatory response. However, it seems that a combination of H. pylori infection and a high-salt environment leads to a much greater chance of developing stomach ulcers and/or cancer. Damaging the mucous bilayer with salt enables H. pylori to directly contact the epithelial cells. Low stomach acid allows H. pylori to more easily survive in the stomach, especially in parts prone to ulceration/cancer such as the corpus. Inflammation generates reactive oxygen species that damage the DNA of epithelial cells, resulting in immediate reduction in function as well as debilitating mutations. Reactive oxygen species generate mutations in the cells lining the stomach that are then enriched by heightened cell turnover. Most mutations result in reduced cell function, which often shows up as cells that produce less mucus or less gastric acid on a permanent basis. However, some mutations are in genes that when damaged result in the cells reproducing at an inappropriately increased rate, oftentimes producing cancer.
A high-salt environment also seems to induce physiological changes in H. pylori that enable the bacterium to survive under the unusual conditions. When the salt concentration in the stomach increases above a certain level, H. pylori becomes stressed and its growth slows. It changes its shape from its regular spiral to an elongated filamentous form (Gancz et al, 2008). Virulence factors (e.g. cagA, vacA, adherins) may be induced depending on the strain of H. pylori present, which enable the bacterium to invade the cells lining the stomach (Loh et al, 2007).
What constitutes high salt? Charnley and Tannenbaum (1985) stated that frequent consumption of foods rich in salt such as soy sauce (18%), dried fish (20%), and pickles (13-25%) would probably lead to increased gastric cell proliferation. Chips and pretzels are similarly salt-rich, and in large and regular amounts would be expected to have similar effects on the gastric lining. The best measure of whether you are taking in too much salt is by having your doctor measure your 24 h urinary sodium output (Sonnenberg 1986).
Stomach ulcers result from an imbalance between destructive factors such as high salt intake and H. pylori infection, and constructive factors such as the mucus-stimulating ability of prostaglandin E2 and Vitamin U. Taking Vitamin U in the form of fresh vegetable juice or supplements will to some extent counteract the negative effects resulting from high salt consumption by rebuilding the protective mucous bilayer lining the stomach. Recall the pioneering cabbage juice studies of Cheney from 70 years ago (more). The role of H. pylori infection was unknown at the time, yet cabbage juice in the absence of supporting antibiotics was effective in healing peptic ulcers.
Whatever means you take to treat your stomach ulcer, it would be wise to reduce exposure to the causative agent(s), whether that be infection with Helicobacter pylori, NSAIDs, a stressful job, the morning donuts, or in this case, a high-salt diet. If you have stomach issues but are not sure what condition you have, visit your doctor for a diagnosis.
Please don't treat stomach cancer with vegetable juice or Vitamin U supplements. The primary role of nutrients is to promote good health and reduce the risk of developing cancer in the first place. Once a cancer has formed, it should be treated with chemotherapy, radiation and/or surgery.