A daily soda, sports drink or glass of sugary punch may carry a health risk that researchers have only recently begun to explore.
A long-running U.S. study found that people who regularly drank sugar-sweetened beverages were more likely to develop stomach cancer than those who almost never drank them. Surprisingly, the same pattern was not seen with artificially sweetened drinks.
Scientists at the Mass General Brigham Cancer Institute reported the findings in Gastro Hep Advances. Senior researcher Andrew T. Chan and his colleagues say this is the first U.S. study to show an association between sugary beverage intake and stomach cancer. The finding is especially interesting because these drinks are consumed by a large share of American adults.
Stomach cancer develops when cells in the stomach begin growing out of control. The disease can be difficult to find early because symptoms such as indigestion, stomach discomfort or poor appetite can easily be mistaken for less serious problems. Although rates vary greatly between countries, gastric cancer remains one of the world’s major causes of cancer death.
Scientists already know about several factors that can raise stomach cancer risk. One of the most important is infection with H. pylori, a common bacterium that can cause years of inflammation inside the stomach. Smoking, family history and certain dietary patterns can also play a role.
Whether sugary beverages belong on that list has been much less clear. Previous studies have connected frequent consumption with obesity, type 2 diabetes and cardiovascular disease, and researchers have reported possible links with several cancers. Evidence for stomach cancer, however, has been limited.
To investigate, the researchers used data from 112,284 people enrolled in the Nurses’ Health Study and Health Professionals Follow-Up Study. These famous research projects have tracked the health and habits of U.S. adults for decades. Participants regularly provided information about what they ate and drank, along with many other lifestyle and medical details.
Over the long follow-up period, 278 participants were diagnosed with stomach cancer. The researchers then examined whether cancer rates differed according to sugary drink intake. Their definition included regular carbonated drinks, punch, lemonade and sports drinks.
People consuming at least one serving of a sugar-sweetened drink each day had a 2.45-fold higher risk of stomach cancer than those consuming less than one serving per month. The researchers adjusted their calculations for several other factors that might influence cancer risk. A similar association appeared in men and women.
The pattern was particularly strong among women. In the Nurses’ Health Study, women drinking more than one sugary beverage per day had roughly three times the risk seen among women who rarely drank them. Greater total intake of fructose, a sugar commonly used to sweeten these beverages, was also associated with more stomach cancer.
The study produced a different result for low-calorie drinks containing artificial sweeteners. Higher consumption of these beverages was not associated with increased stomach cancer after other factors were considered. This does not prove that artificially sweetened beverages are protective or completely risk-free, but they did not show the same stomach cancer signal in this research.
The team also explored whether H. pylori might explain the findings. Infection information was available for a much smaller group of 940 participants, and slightly more than one-third had evidence of the bacterium. Sugary beverage intake was not associated with H. pylori infection in that group.
Scientists do not yet know how sugary drinks might be connected with stomach cancer. Frequent consumption can deliver large amounts of sugar very quickly, contributing to higher calorie intake, weight gain and problems controlling blood sugar. The researchers also noted the association with fructose, but further studies are needed to determine whether fructose itself has a special effect on the stomach or whether it simply reflects a diet high in sugary drinks.
A major strength of the research is its long follow-up and unusually detailed information about participants’ diets and lifestyles. That allowed researchers to account for many known differences between people who drank more or fewer sugary beverages. Even so, this type of study cannot establish cause and effect.
The number of stomach cancer cases was also fairly small compared with the total study population. H. pylori information and family history were incomplete, and most participants were white, so the findings need to be tested in more diverse groups. It is also possible that an unmeasured habit linked with sugary drink consumption partly explains the higher cancer rate.
The results therefore should not be interpreted as showing that one sugary drink will cause stomach cancer. They show a statistical association that deserves further investigation, particularly because the reported difference in risk was substantial. More studies will be needed to confirm the link and uncover the biological reasons behind it.
For now, the research adds another reason to reconsider how often sugary drinks appear in the daily diet. Cutting back is already recommended because these beverages provide large amounts of added sugar with little nutritional value and can contribute to obesity and diabetes.
If future research confirms the stomach cancer connection, the benefits of reducing them could be even broader than previously understood.
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Source: Mass General Brigham.
