For many of us, a hot cup of tea or coffee is part of our daily routine – a morning ritual, a moment to ourselves, or simply a chance to stop and recharge.
But new research suggests there may be good reason not to drink it too hot.
A major UK study involving almost one million people has found that those who preferred their drinks “very hot” had around three times the risk of developing oesophageal squamous cell carcinoma (SCC), one of the two main forms of oesophageal cancer, compared with people who took their drinks warm.
The message isn't that we need to give up tea or coffee. It is simply that allowing a drink to cool until it feels comfortable can be a sensible habit.
Researchers from the University of Oxford followed almost 980,000 people for around 14 years. Participants were asked whether they generally drank hot beverages “very hot,” “hot” or “warm.”
The study found a clear pattern: as preferred drinking temperature increased, so did the risk of SCC. Frequency also appeared to matter. Once temperature was taken into account, people drinking six or more hot drinks a day had a 71% higher risk of SCC than those drinking fewer than six.
Importantly, the researchers found little evidence of the same association with oesophageal adenocarcinoma (AC), the other main type of oesophageal cancer.
The findings also fit with earlier research from other parts of the world linking beverages consumed at around 70°C or above with an increased risk of oesophageal cancer. In 2016, the International Agency for Research on Cancer classified drinking very hot beverages as “probably carcinogenic to humans”.
One possible explanation is surprisingly straightforward. Repeated exposure to very hot liquid may damage the cells lining the oesophagus. Over many years, that repeated irritation could make cancer more likely to develop.
There are limitations, though. The researchers didn't measure the temperature of every cup. People simply described how hot they liked their drinks, and one person's idea of “very hot” may be quite different from another's.
Nor can the study prove that hot drinks directly cause cancer. Smoking and alcohol remain important risk factors for SCC.
Even so, the scale of this study, together with previous international research, makes its practical message worth paying attention to.
Cancer Research UK isn't suggesting we stand beside the kettle with a thermometer or time every cup before taking a sip. Nor does the research mean cafés and restaurants need to start serving lukewarm coffee.
The advice is much simpler: if your drink feels too hot to drink comfortably, let it cool down.
This is useful research. We can still enjoy the cup of tea, the coffee break and the familiar ritual. We just don't need to rush the first sip.
