If you love your cuppa steaming hot, new research suggests you may want to give it a few minutes before taking that first sip.
In the largest study of its kind, researchers found that regularly drinking very hot beverages was linked to a higher risk of developing a type of oesophageal cancer.
Published in the International Journal of Cancer, the study followed 977,282 middle-aged adults in the UK for around 14 years, looking at how often they drank hot drinks and how hot they liked them.
Participants were asked whether they preferred their drinks warm, hot or very hot. Compared with those who drank them warm, people who chose “hot” had around twice the risk of developing oesophageal squamous cell carcinoma. For “very hot” drinkers, the risk was about three times higher.
Drinking six or more hot drinks a day was also linked to a 71 per cent higher risk than having less than six.
The link was specific to squamous cell carcinoma, one of the two main types of oesophageal cancer. Researchers didn’t see the same association with oesophageal adenocarcinoma.
So, how hot is too hot?
The study didn’t measure the temperature of each cup. Instead, people described their drinks as warm, hot or very hot – and one person’s piping hot may be another’s just right.
“More research is now needed to identify the exact drink temperatures linked to this increased risk,” lead researcher Dr Keren Papier said.
However, this isn’t the first warning about the temperature of hot drinks. In 2016, the World Health Organization’s International Agency for Research on Cancer classified beverages consumed above 65°C as “probably carcinogenic to humans”.
For context, water boils at 100°C and can still be around 90°C to 95°C when poured into a cup. A splash of milk will bring the temperature down, but your milky tea or coffee may still be hotter than you realise.
Why could hot drinks increase cancer risk?
Very hot liquid can damage the cells lining the oesophagus, the tube that carries food and drinks from your mouth to your stomach. Researchers believe that repeated heat damage may lead to inflammation and changes in the cells over time.
The findings support earlier studies from South America, Asia, Africa and the Middle East, where drinks such as maté are often consumed at very high temperatures. This latest research shows a similar pattern in the UK, where tea and coffee are more common.
Do you need to give up hot drinks?
Oesophageal cancer is relatively uncommon, so the findings don’t mean that people who enjoy a hot cup of tea or coffee will develop it.
Smoking and drinking alcohol are also much more established risk factors for the disease.
Fiona Osgun, head of health information at Cancer Research UK, which funded the study, stressed that “the most important ways to reduce the risk of this cancer type are not smoking and cutting down on alcohol.”
And when it comes to your morning brew, there’s no set amount of time you need to wait.
“It’s difficult to put an exact time on how long a hot drink should be left to cool. But if you’re worried, we’d suggest just waiting until it’s comfortable to drink rather than drinking it while it’s still very hot,” Ogun said.
