Tea and coffee drinkers who drink their beverages piping hot—above 149 degrees Fahrenheit (65 degrees C)—are nearly three times more likely to develop esophageal cancer than those who let their drinks cool, according to a recent Oxford-led study of almost 1 million people, the largest of its kind.
The study counted any drink at or above 149 degrees F as very hot—hot enough to scald skin on contact. People who regularly drank their tea or coffee at that temperature had roughly triple the esophageal cancer risk of those who drank their beverages warm.
Drinking six or more very hot beverages per day further increased the risk.
The study, recently published in the International Journal of Cancer and funded by Cancer Research UK, tracked 977,282 UK participants for an average of 11 to 14 years. Researchers recorded 1,045 cases of squamous cell esophageal cancer, a type that starts in the cells lining the esophagus, over that period—about 0.1 percent overall.
How Might Heat Cause Cancer?
Very hot liquids can injure the lining of the esophagus, just as they can burn the mouth, Dr. Jason Korenblit, a leading health expert contributor for JustAnswer and a board-certified gastroenterologist at Orlando’s Center for Digestive Health who was not involved in the study, told The Epoch Times.
“Repeated exposure may create a cycle of injury, inflammation, and repair. Over time, ongoing inflammation can damage DNA,” Korenblit said. “And this may increase the chance that abnormal cells survive and eventually develop into cancer.”
He emphasized that this is a proposed explanation for the association, as the UK study did not directly measure this process. The researchers tracked drinking habits and cancer diagnoses. They did not biopsy esophageal tissue to directly observe the inflammatory process.
The cancer linked to drink temperature in this study was squamous cell carcinoma, which develops from cells lining the esophagus.
One finding that supports the heat theory.
“Researchers found similar patterns among people who mainly drank tea and those who mainly drank coffee,” Korenblit said. “That supports heat exposure as the likely concern.”
Notably, the study found no link between drink temperature and adenocarcinoma, the more common form of esophageal cancer in the United States, which is tied to chronic acid reflux, Barrett’s esophagus, and obesity rather than heat exposure. The heat-related risk applies specifically to squamous cell carcinoma.
Cancer Research UK recommends waiting until a hot drink feels comfortable before drinking it to avoid potential harm.
The study authors noted that more research is needed to determine which temperatures pose the greatest risk.
Put the Risk in Perspective
A tripled risk may sound alarming, but esophageal cancer is rare to begin with. It affects about 1 percent of the UK population and 0.5 percent of the U.S. population over a lifetime. In this study, even with the increased risk, cases occurred in roughly 0.1 percent of participants overall.
Avoiding very hot drinks, the researchers estimate, would prevent somewhere between one and two cases for every 10 that currently occur among people who drink very hot beverages. This represents a modest but real reduction, not a guarantee of protection.
By comparison, smoking and alcohol remain far greater drivers of esophageal cancer than drink temperature.
“Smoking and alcohol are proven causes of cancer, and using both raises esophageal cancer risk substantially more than either alone,” Korenblit said.
Safest Temperature for Coffee
Researchers defined temperatures below 140 degrees F (60 degrees C) as a safe temperature range.
A separate study involving 118 young adults found that most considered black coffee too hot only if it was at least 158 degrees F.
Early symptoms of esophageal cancer can include heartburn, indigestion, throat or chest pain, and weight loss, Korenblit said, but the warning sign that deserves particular attention is new or worsening difficulty swallowing, especially a feeling that food is sticking.
“Other symptoms can include painful swallowing, unexplained weight loss, discomfort behind the breastbone, persistent hoarseness or coughing, and heartburn or indigestion,” he said. “These symptoms often have other causes, but they should be evaluated.”
