Drinking sugary beverages every day may be linked to a higher risk of stomach cancer, according to a large U.S. study.
Researchers found that adults who regularly consumed drinks with added sugar had a greater chance of developing the disease over many years. Drinks made with artificial sweeteners did not show the same link.
The research was carried out by scientists from the Mass General Brigham Cancer Institute and was published in the journal Gastro Hep Advances. The study adds stomach cancer to a growing list of diseases that have been associated with frequent sugary drink consumption. Earlier research has also raised concerns about links with colorectal, breast and liver cancers.
Sugary drinks are a major part of the American diet. About 65% of U.S. adults report drinking at least one sugar-sweetened beverage each day. These drinks can include regular soft drinks, fruit punch, lemonade and sports drinks.
Stomach cancer, also called gastric cancer, begins when abnormal cells grow in the lining of the stomach. It is less common in the United States than some other cancers, but worldwide it remains a major health problem. It is the fifth leading cause of cancer death globally.
Researchers examined information from 112,284 adults who took part in two long-running U.S. studies: the Nurses’ Health Study and the Health Professionals Follow-Up Study. These projects have collected detailed information about participants’ diets, lifestyles and health for decades. During the follow-up period, 278 people developed stomach cancer.
The researchers compared people who rarely drank sugary beverages with those who consumed them regularly. After taking other possible risk factors into account, people drinking at least one sugary beverage per day had about 2.45 times the risk of stomach cancer compared with people drinking less than one per month. The association appeared in both men and women.
Among women in the Nurses’ Health Study, the difference was even larger. Women drinking more than one sugary beverage a day had about three times the risk of stomach cancer compared with women who rarely consumed these drinks. Higher intake of fructose, a type of sugar commonly found in sweetened beverages, was also linked with more cases of stomach cancer.
The researchers also studied artificially sweetened drinks, such as low-calorie carbonated beverages. After adjusting for other health and lifestyle differences, these drinks were not associated with a higher rate of stomach cancer.
That finding suggests the association may be related to sugar or other features of sugary drinks rather than simply drinking sweet-tasting beverages.
One important cause of stomach cancer is infection with Helicobacter pylori, usually called H. pylori. This bacterium can live in the stomach for years and cause long-lasting inflammation that raises cancer risk. The team had information about H. pylori infection for 940 participants, and just over one-third showed evidence of infection.
In this smaller group, sugary drink consumption was not linked with whether someone had H. pylori. This suggests that the beverage association was not simply explained by sugary drink consumers having more H. pylori infections. However, the limited number of participants with infection data means this part of the study should be interpreted cautiously.
There are several possible explanations for the findings, but the study cannot prove which one is correct. Large amounts of added sugar can contribute to weight gain, poor blood sugar control and changes in metabolism, all of which may influence cancer development.
Fructose may also affect the body differently from some other carbohydrates, but more research is needed to understand whether it has a direct role in stomach cancer.
The study has important strengths because it followed a very large group for many years and repeatedly collected detailed information about diet and health. However, it was observational, meaning researchers watched what people did rather than assigning them to drink sugary beverages.
People who frequently consume sugary drinks may differ from people who avoid them in ways that are difficult to measure completely.
Only 278 stomach cancers occurred despite the study’s large population, so some estimates are based on relatively small numbers of cases.
The participants were also mainly white health professionals, which makes it uncertain whether the same results apply equally to other racial, ethnic and socioeconomic groups. Information about family history of stomach cancer and H. pylori infection was also limited.
Overall, the study provides an important warning signal rather than proof that sugary drinks cause stomach cancer. The size of the reported association is notable, but it needs confirmation in other populations before firm conclusions can be drawn.
Still, reducing sugary drinks already has well-established benefits for weight, blood sugar and dental health, so choosing water or other unsweetened drinks remains a sensible health choice.
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Source: Mass General Brigham.
