Adding salt to food regularly could raise risk of stomach cancer

This prospective study used data from the UK Biobank, including 471,144 participants in its analysis.

They excluded participants who were missing data on adding salt to food, body mass index (BMI), or urinary sodium or potassium levels. They also excluded participants who had cancer at baseline and participants who had kidney disease.

Participants filled out baseline questionnaires to indicate how often they added salt to food, excluding the salt they used while cooking. Participants could respond with never/rarely, sometimes, usually, or always.

Researchers further measured participants’ urinary sodium, creatinine, and potassium levels. They were also able to estimate 24-hour urinary sodium excretion.

They accounted for several covariates, including physical activity levels, age, education level, ethnicity, sex, and alcohol use. They were also able to take into account red meat consumption and fruit and vegetable intake. The median follow-up period with participants was 10.9 years.

During the follow-up time, 640 cases of gastric cancer among participants were documented. In general, participants who reported always adding salt to food at the table were more likely to be past or current smokers, have a high level of alcohol intake, and have a lower education level.

Researchers found that participants who always added salt at the table were at 41% higher risk for gastric cancer compared to participants who never or rarely added salt to food at the table.

While they found that adding salt to food more often was associated with increased 24-hour urinary sodium levels, they did not find a significant association between 24-hour urinary sodium levels and gastric cancer.

They also found that in a subset of 198,900 participants, responses to the frequency of adding salt at the table positively correlated with daily sodium intake levels.

The results suggest that examining the frequency of added salt use at the table may be a simple way to assist in identifying individuals with high salt intake who may, in turn, be at risk for gastric cancer.

Anton Bilchik, MD, PhD, surgical oncologist, chief of medicine, and Director of the Gastrointestinal and Hepatobiliary Program at Providence Saint John’s Cancer Institute in Santa Monica, CA, not involved in this study, told Medical News Today “[t]he study provides further evidence of the association between diet, particularly one rich in salt and gastric cancer.” He added:

“It has been suggested that one of the major causes of gastric cancer in Asian countries is from fish high in salt content. Much less is known about the association of salt intake and gastric cancer in Western countries. It is well known that excessive use of salt is associated with a higher risk of hypertension and cardiovascular disease. This study provides additional evidence that salt routinely taken with meals increases the risk of developing gastric cancer. It is therefore imperative that people be aware of the deleterious effects of excessive salt intake.”

Many factors contribute to someone’s risk for gastric cancer, including smoking, increased age, obesity, and family history.

Researchers of the current study note that higher salt intake has been associated with a higher risk for gastric cancer in Asian studies.

However, there have not been many studies in this area among Western population groups.

Bilchik offered the following insight to MNT:

“Gastric cancer is very serious especially if it presents at an advanced stage. It is one of the most common cancers in Asian countries and there is therefore greater emphasis on screening measures than in Western countries. Also, the pattern of presentation is different with patients from Western countries presenting more often with cancer in the upper part of the stomach, a more challenging location to manage than Asian countries where cancers are more often found in the lower part of the stomach. This may be related to a higher incidence of obesity and gastroesophageal reflux disease in Western countries — risk factors for upper gastric cancer.”

This study has several limitations. First, it cannot prove that increased salt consumption causes gastric cancer. It also relies on participant reporting, which does not always produce the most accurate data, and they did not have complete data on salt intake in foods.

The UK Biobank is also not necessarily reflective of the general population, so research with other groups with greater diversity may be warranted, and the results cannot be generalized. The link between salt intake and gastric cancer risk may be stronger than observed in this study.

Researchers also used an estimation method to measure 24-hour urinary sodium levels, which does not always accurately represent this level.

They further note that the case numbers were inadequate to examine the effect of possible modifiers like sex, age, ethnicity, smoking status, or Helicobacter pylori infection.

There is the possibility for residual confounding, and future research can also focus more on gastric cancer subtypes.

This data continues to support the idea that excess salt intake is associated with an increase in gastric cancer risk. However, there are many other reasons to limit salt intake. For example, consuming too much sodium can also increase the risk of high blood pressure and kidney problems.

People can work towards making wiser choices regarding salt consumption to reduce their overall salt intake.

This can include working with a registered dietitian who can help with individualized strategies.

Registered dietitian Karen Z. Berg, not involved in this research, offered the following insights on salt reduction ideas to MNT:

“People get so caught up in their habits that they add salt to an already salty food. Taste your food first, and hopefully more often than not, you won’t have to add salt. Also, I tell people not to cook with salt. Use spices instead to enhance flavors. Salt can be added later if you absolutely feel like it’s necessary. Your taste buds get used to salt, and the more you add salt to your food, the more you’re going to want it. So I tell people to really be conscious of that and try to ween themselves off of salt as much as possible.”