Most of us find comfort and enjoyment in a hot beverage, be it tea, coffee, or chocolate. Especially on a cold night, a hot cup of any drink seems to be all we need. But a new recommendation by the World Health Organization (WHO) advises that consuming excessively hot drinks may increase the risks for esophageal cancer.
What exactly counts as “excessively hot”? According to WHO, these are drinks that exceed 149 degrees Fahrenheit (65 degrees Celsius). For reference, the temperature of lukewarm (tepid) water is around 105 degrees Fahrenheit (40.5 degrees Celsius). And water boils at 212 degrees Fahrenheit (100 degrees Celsius).
The findings come after the team, composed of over 20 scientists in 10 countries, reviewed data from over 1,000 studies in many different types of cancer. From the data, the consensus was that very hot liquids are “probably carcinogenic to humans” to cells in the esophagus. "There is physical evidence that very hot beverages can contribute to cell injury in the esophagus and thus contribute to cancer formation," said Mariana Stern, an associate professor at the Keck School of Medicine at the University of Southern California who was part of the research team.
The classification of “probable carcinogen” ties hot liquids to DDT – a hazardous insecticide, and the human papillomavirus – an agent linked to cervical cancer.
"We were now able to evaluate more carefully the effect of mate itself from the effect of temperature, and we concluded that the observed links between mate drinking and cancer of the esophagus seem to be largely driven by drinking [yerba] mate very hot," Stern said. "Similar associations are seen for other very hot beverages, like tea or coffee."
While it’s common sense not to drink boiling liquids, it’s harder to conceptualize what 149 degrees Fahrenheit is like. For coffee, the ideal brewing temperature, according to the National Coffee Association, is between 195 to 205 degrees. Coffee waiting to be served is recommended to be between 180-185 degrees Fahrenheit. Thus, for people who are used to drinking piping hot coffee, they may be surprised to find that 149 degrees Fahrenheit is a lot cooler than they expect.
There is some good news, though. In contrast to the classification of hot liquids as a probable carcinogen, the WHO downgraded coffee as a possible carcinogen. That is, if it’s not boiling hot. In fact, they cited that a daily cup of joe could have anti-cancer benefits. "For many cancer types, we found clear evidence that coffee is not carcinogenic," Stern said. "In fact, we found that coffee protects against some cancers such as liver and uterine endometrium cancer."
So, the moral of the research? For the 64 percent of Americans who reported to drink at least one cup of coffee a day, feel free to enjoy your coffee, but do wait to make sure it’s not very hot. Or opt for iced coffee, instead!
Additional source: University of Southern California press release