In a recent study published in Gastric Cancer, researchers investigated how frequently people in the United Kingdom add salt to their food at the table and how this relates to their risk of developing stomach cancer.
Study: Adding salt to food at table as an indicator of gastric cancer risk among adults: a prospective study. Image Credit: Soho A Studio/Shutterstock.com
Background
Recent research has raised concerns about the rising prevalence of stomach cancer among young individuals worldwide.
While researchers associate dietary salt consumption with an increased incidence of gastric cancer among Asians, there are limited results from Western cultures from case-control studies.
Salt can damage the stomach mucosa, increasing its vulnerability to Helicobacter pylori colonization and raising the risk of gastric cancer through mechanisms other than infection, such as harming gastric epithelial cells with chemical carcinogens and N-nitroso molecules. Existing evidence on total or added salt consumption has varied outcomes, warranting further research.
About the study
In the present prospective study, researchers investigated the link between adding salt to foods at the table and the risk of stomach cancer.
The team used multivariate Cox regressions to assess the relationship between the frequency of salt addition to foods and the risk of developing stomach cancer among 471,144 United Kingdom Biobank individuals.
They excluded individuals with prior histories of cancer or renal illness and those with incomplete data on salt intake, urine sodium or potassium levels, and body mass index (BMI).
At baseline (between 2006 and 2010), the team used touchscreen surveys to determine the frequency with which participants incorporated salt in their meals. They used the ion-selective electrode method to assess urinary sodium, potassium, and creatinine levels in spot urine samples and INTERSALT equations to predict 24-hour urinary sodium excretion.
The researchers determined gastric cancer incidence based on the linked national cancer registry data and the tenth revision (ICD-10) codes of the International Classification of Diseases.
In addition, they examined the relationship between spot urine sodium and gastric cancer risk and the relationship between the frequencies with which participants added salt to meals and other sodium consumption indicators (total sodium in diet and urine).
The team used Cox proportional hazard modeling to calculate the hazard ratios (HR) for the analysis. Covariates in the study were age, body mass index (BMI), sex, ethnicity, educational attainment, Townsend index, smoking, food, physical activity, alcohol intake, comorbidities, diuretic usage, and Helicobacter pylori infection status.
In sensitivity analyses, the researchers eliminated non-white people with comorbidities and Helicobacter pylori infections and the initial follow-up year.
Results
Over an 11-year median follow-up, the researchers identified 640 occurrences of stomach cancer. Individuals who add salt to meals at the table are more likely to be less educated, non-white males, past or current smokers, living in disadvantaged regions, and consuming significant amounts of alcohol (≥16.0 grams per day).
In multivariate analyses, the HR value for the risk of gastric cancer among people who usually add salt to their food at the table vs. those who never or seldom do so was 1.4.
The researchers discovered a linear and positive relationship between estimated 24-hour urine sodium levels and the frequency of salting meals. There were no significant relationships between 24-hour urine sodium estimates and gastric cancer (HR, 1.2).
Sensitivity analyses produced similar findings. There was no evidence of heterogeneity by cancer location, with HRs of 1.0 for 264 cardiac patients and 1.1 for 163 non-cardia cases.
Individuals who added salt to table foods never or rarely, sometimes, frequently, or always had urine sodium levels of 2,932 mg, 3,028 mg, 3,129 mg, and 3,168 mg per day. Similarly, the log-spot urine sodium concentrations at the corresponding frequencies were 1.8, 1.8, 1.9, and 1.9 mmol/L.
The individuals' frequency groups corresponded to 1,864 mg, 2,040 mg, 2,196 mg, and 2,254 mg of sodium consumed daily.
Conclusions
The study found that salt addition to foods on the table increases the risk of stomach cancer among UK adults. Individuals who constantly incorporated salt in their diets showed a 41.0% higher chance of acquiring stomach cancer compared to those who seldom or never added salt.
The researchers also discovered a favorable dose-response relationship between spot urine sodium levels and 24-hour sodium excretion in urine.
However, considering 24-hour urine salt as an exposure revealed no relationship with stomach cancer risk. After eliminating stomach cancer cases diagnosed in the initial follow-up year, these associations were slightly more robust and indicated reverse causation.
The findings are consistent with previous meta-analytical research of prospective trials reporting higher stomach cancer risks among Asian communities consuming a lot of salt, pickled foods, salted seafood, and processed meat.
Further research with larger sample sizes is required to evaluate possible variations across cancer subtypes and improve quantifying the association between salt intake and stomach cancer risk.
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