How hot is too hot for a drink?
There is a credible link between drinking hot beverages such as tea and coffee and the risk of oesophageal cancer. For the first time, researchers have been able to answer the question of just how hot is too hot.
Cancer of the oesophagus kills over 500,000 people worldwide each year with most of these deaths in Asia, Africa and South America. In Australia, it claims over 1,300 people every year. Smoking, drinking and obesity are known risk factors and drinking very hot beverages also appears on the list.
There is a plausible link between drinking hot beverages and cancer of the oesophagus. Hot beverages can scald the lining of the oesophagus just as easily as it does if spilt on the skin. Repeated heat damage to cells lining the oesophagus has the potential to initiate the cancer process through inflammatory stress.
So the question is: just how hot is too hot?
A team of researchers has looked closely at this question by objectively and subjectively measuring the drinking temperature of tea in a large group of people who were then followed for many years to determine their future risk of oesophageal cancer.
At the beginning of the study in 2004, a raft of health and lifestyle information was collected on more than 50,000 people in Iran. One novel piece of information was how hot they enjoyed their tea.
To do this, tea was served during the health interview at an exact temperature of 75 degrees Celsius. The participants were asked to sip the tea and comment on how closely it matched the temperature of tea they normally drank. If they preferred it cooler, the tea was allowed to drop 5 degrees in temperature before the person was asked to try it again until they got to their preferred drinking temperature.
Armed with this objective measure of tea temperature preference it was then a matter of waiting some years to see how many people in the study went on to develop oesophageal cancer.
Drinking tea above 60 degrees Celsius, having a stated preference for ‘hot tea’, and waiting only a short time from pouring to drinking were all linked to a higher risk of cancer of the oesophagus.
Drinking more than 700 mL of tea each day above 60 degrees almost doubled the risk compared to people who preferred cooler tea.
There is no need to swear off tea just yet as regular tea drinking is also linked to lowering the risk of several cancers. It is just that it is best to give tea and coffee time to cool before you start to drink it.
Drinking very hot tea and other beverages can increase the risk of oesophageal cancer, so it is advisable to wait for beverages to go from ‘scalding’ to ‘tolerably hot’ after being poured.
Last Reviewed: 27/03/2020
© Norman Swan Medical Communications.
For reference: Islami F et al. A prospective study of tea drinking temperature and risk of esophageal squamous cell carcinoma. International Journal of Cancer Epub online 20 March 2019 doi: 10.1002/ijc.32220.