Research indicates a troubling connection between the consumption of very hot beverages and an elevated risk of oesophageal cancer. A recent study involving nearly half a million adults in the United Kingdom found that individuals who regularly consume hot drinks, particularly tea and coffee, may be significantly more susceptible to this serious health condition.
In 2016, the International Agency for Research on Cancer categorized very hot beverages, defined as those served above 65°C, as “probably carcinogenic to humans.” This classification places the risk level of consuming these drinks in the same category as factors such as indoor wood smoke emissions and a high intake of red meat. The agency’s findings suggest that it is the temperature of the beverages, rather than the drinks themselves, that poses a health risk.
Studies, especially from South America, have shown a correlation between the consumption of maté—a traditional herbal drink typically served at around 70°C—and increased rates of oesophageal cancer. Additional research from regions in the Middle East, Africa, and Asia has reinforced this link, though substantial research in Western populations had been lacking until now.
The recent UK study revealed that individuals who drink eight or more cups of very hot tea or coffee daily are almost six times more likely to develop oesophageal cancer compared to those who do not consume hot beverages. This alarming statistic highlights the potential dangers associated with habitual consumption of hot drinks.
The mechanism by which hot drinks might lead to cancer involves damage to the cells lining the oesophagus. Over time, repeated exposure to high temperatures can result in cellular injury, which researchers have suggested can contribute to the development of cancer. This theory has been explored for nearly a century.
Animal studies provide some insight into how this damage occurs. For example, a 2016 study involving mice showed that those exposed to water at 70°C developed precancerous lesions in their oesophagus more quickly than those given cooler water. Another hypothesis posits that the heat may compromise the oesophagus’s protective barrier, making it more vulnerable to further damage from gastric acid reflux.
The quantity and method of consuming hot beverages also appear to affect cancer risk. Research indicates that taking large sips significantly raises the temperature inside the oesophagus, potentially leading to thermal injury. One study demonstrated that a sip of 65°C coffee measuring 20 millilitres could increase the oesophageal temperature by as much as 12°C. In contrast, an occasional small sip at the same temperature is less likely to result in lasting harm.
As for what constitutes a safe drinking temperature, many hot beverages are brewed at high temperatures—often close to the boiling point of water. For instance, takeaway coffees may be served around 90°C to allow for cooling before consumption. To mitigate potential risks, a study from the United States identified an optimum drinking temperature for coffee at approximately 57.8°C.
To enjoy hot drinks more safely, experts recommend slowing down the drinking process. Allowing beverages to cool for a few minutes can significantly reduce their temperature. Research suggests that a hot drink can drop by 10–15°C within five minutes. Additionally, taking small sips can help assess the drink’s temperature, reducing the risk of heat damage to the oesophagus.
Dr. Vincent Ho, an Associate Professor and Clinical Academic Gastroenterologist at Western Sydney University, emphasizes the importance of awareness regarding the temperature of beverages. With increasing evidence linking very hot drinks to serious health risks, it may be prudent for consumers to reconsider their drinking habits for long-term health benefits.
