While there are plenty of reasons to enjoy drinking tea, you may want to let that piping hot beverage cool down a bit before you take a sip. A new study, published in International Journal of Cancer, adds to a body of evidence that finds drinking very hot tea may be linked to an increased risk of esophageal cancer.
"Many people enjoy drinking tea, coffee, or other hot beverages. However, according to our report, drinking very hot tea can increase the risk of esophageal cancer, and it is therefore advisable to wait until hot beverages cool down before drinking," the lead author of the study, Dr. Farhad Islami of the American Cancer Society, said in a statement.
For the study, Islami and his team followed more than 50,000 individuals, aged 40 to 75 years old, for a median of 10 years. An analysis during a follow-up period found 317 of those people went on to develop esophageal cancer. Esophageal cancer — cancer of the esophagus, the tube connecting the throat and stomach — is a deadly form of the disease. The National Cancer Institute reports about 17,290 Americans were diagnosed with it last year, and only about 19 percent of patients survive 5 years.
The researchers found that drinking 700 milliliters — about three cups — per day or more at a higher temperature (140°F or hotter) was associated with a 90 percent higher risk of esophageal cancer, compared to people who drank the same amount at a temperature below 140°F.
This is not the first time drinking very hot beverages has been linked to an increased cancer risk. In 2016, the World Health Organization issued a report that found that drinking, and it classified them as "probably carcinogenic" to humans.
In particular, it cited countries including China, Iran and those in South America, where teas such as the bitter herbal infusion mate are traditionally drunk at extremely high temperatures — above 65 or 70 degrees Celsius (150 or 160 degrees Fahrenheit).
In the U.S. and Europe, hot drinks are typically served at lower temperatures.
In 2018, another study out of China, published in the Annals of Internal Medicine, found that drinking very hot tea, along with smoking and drinking alcohol, was linked to an increased risk of squamous cell carcinoma of the esophagus.
While experts haven't identified the underlying mechanism behind the cancer link, researchers believe frequently consuming scalding hot liquids may result in long-term injury to the cells lining the esophagus.
"It doesn't take a scientist to appreciate that repeated irritation of any body surface increases your risk of cancer. Sunburn gives us skin cancer, smoking gives us lung cancer, and many foods and drinks contribute to risk of gastrointestinal cancers," Dr. James Doidge, a senior research associate at University College London, told Science Media Centre, an independent organization promoting the reporting of evidence-based science.
Doidge, who was not involved in the study, also put the overall risk into context.
"If you enjoy your tea piping hot and we take the results on this study on face value, then we are talking about an additional lifetime risk of esophageal cancer of around one in one hundred for a lifetime of drinking hot tea. Not an insubstantial risk but one that should be balanced against the pleasure that you personally derive from your daily ritual," he said.
Other experts point out the importance of other risk factors in preventing cancer.
"Quitting smoking and reducing alcohol consumption are much more significant for reducing cancer risk than the temperature of what you're drinking," Dr. Otis Brawley, former chief medical officer of the American Cancer Society, told CBS News in 2016. Brawley said the cancer risk posed by drinking hot beverages was similar to that posed by eating pickled vegetables.