Recent research has indicated that consuming very hot beverages, such as tea and coffee, may significantly increase the risk of developing oesophageal cancer. The International Agency for Research on Cancer (IARC) has classified drinks served at temperatures above 65°C as “probably carcinogenic to humans.” This classification places the risk of very hot drinks in the same category as certain harmful substances, such as emissions from indoor wood smoke and excessive red meat consumption.
In 2016, the IARC found that the temperature of the beverage, rather than the drink itself, is primarily responsible for the associated health risks. This conclusion is supported by evidence from South America, where high consumption of maté, a traditional herbal drink typically served at around 70°C, has been linked to a higher incidence of oesophageal cancer.
Recent Findings in the United Kingdom
A large-scale study conducted in the United Kingdom this year examined nearly half a million adults and confirmed that drinking excessive amounts of very hot beverages correlates with an increased risk of oesophageal cancer. The study revealed that individuals who consumed eight or more cups of very hot tea or coffee daily were nearly six times more likely to develop this type of cancer compared to those who abstained from hot drinks.
The mechanism through which hot beverages may lead to cancer involves damage to the cells lining the oesophagus. Over time, this damage can potentially result in cancer. This connection has been a subject of investigation for nearly nine decades, with animal studies suggesting that very hot liquids can accelerate cancer growth. For instance, a study from 2016 demonstrated that mice exposed to water at 70°C were more likely to develop precancerous growths than those given cooler water.
Understanding the Risks of Consumption
The risk associated with hot drinks may also depend on both the quantity consumed in one sitting and the speed of consumption. Research indicates that taking large sips can significantly raise the temperature inside the oesophagus, potentially causing heat injury. A study measuring the internal temperature of participants drinking hot coffee found that a sip of 20 millilitres of 65°C coffee could increase oesophageal temperature by up to 12°C.
While occasional small sips of a drink at this temperature are unlikely to pose long-term health risks, habitual consumption of large quantities of very hot beverages may elevate the risk of oesophageal cancer over time.
As for what constitutes a safer drinking temperature, brewing methods often yield beverages close to the boiling point. For example, takeaway drinks may be served at approximately 90°C, allowing for cooling before consumption. A study from the United States proposed an ideal drinking temperature for coffee at 57.8°C, balancing the need to minimize heat injury while preserving flavor.
To enjoy hot drinks safely, it is advisable to slow down and allow beverages to cool before sipping. Research has shown that a hot drink’s temperature can decrease by 10–15°C within five minutes. Additionally, taking small sips can help mitigate risks associated with large amounts of hot liquid.
According to Vincent Ho, Associate Professor and Clinical Academic Gastroenterologist at Western Sydney University, understanding these risks can help individuals make informed choices about their beverage consumption. As research continues, it remains essential to balance the enjoyment of hot drinks with awareness of potential health implications.
