A recent study has highlighted a concerning link between the consumption of very hot drinks and an increased risk of oesophageal cancer. This finding, confirmed by research involving nearly half a million adults in the United Kingdom, suggests that drinking beverages at temperatures above 65°C may pose serious health risks.
The International Agency for Research on Cancer (IARC) classified beverages consumed at very high temperatures as “probably carcinogenic to humans” in 2016. This classification places the risk of drinking very hot beverages alongside factors such as indoor wood smoke emissions and high consumption of red meat. The IARC’s assessment indicates that it is the temperature of the beverages, rather than the drinks themselves, that contributes to the increased cancer risk.
Studies conducted primarily in South America have shown a correlation between the consumption of maté, a traditional herbal drink typically enjoyed at around 70°C, and a heightened risk of developing oesophageal cancer. This link has been supported by additional research in regions such as the Middle East, Africa, and Asia. However, until recently, substantial research on this issue in Western populations was lacking.
The recent study in the United Kingdom adds weight to these findings, revealing that individuals who consume eight or more cups of very hot tea or coffee daily are nearly six times more likely to develop oesophageal cancer compared to those who do not regularly consume hot beverages.
Understanding the mechanism behind this relationship involves examining how extremely hot drinks can damage the oesophagus. It is believed that the heat can harm the cells lining the oesophagus, potentially leading to cancer over time. This connection was first proposed nearly 90 years ago and has since been supported by animal studies. For instance, a 2016 study involving mice predisposed to cancer indicated that those given water at 70°C were more likely to develop precancerous growths compared to those given cooler water.
Another theory suggests that heat can impair the normal barrier of the oesophagus, making it more susceptible to damage from gastric acid reflux. Over time, this chronic injury may increase the likelihood of developing cancer.
The risk of developing cancer may not only depend on the temperature of the drink but also on how much is consumed at one time. Research indicates that larger sips can elevate the temperature within the oesophagus more significantly than smaller sips. For example, a 20 millilitre sip of coffee at 65°C can raise the oesophageal temperature by up to 12°C. This sustained heat exposure from larger sips can lead to long-term damage, potentially increasing cancer risk.
As for what constitutes a safe temperature for hot drinks, brewing methods for coffee often approach boiling point, with takeaway beverages sometimes served at approximately 90°C. A study conducted in the United States determined that an ideal serving temperature for coffee, which balances flavour retention and the risk of heat-related injuries to the oesophagus, is around 57.8°C.
To mitigate risks while enjoying hot beverages, experts recommend allowing time for drinks to cool. Research indicates that a hot drink can lose 10–15°C in just five minutes. Additionally, taking smaller sips can help prevent significant temperature increases within the oesophagus, reducing potential damage to its lining.
Vincent Ho, an Associate Professor and Clinical Academic Gastroenterologist at Western Sydney University, emphasizes the importance of moderation and caution when consuming hot drinks. Understanding the health implications associated with beverage temperatures is crucial for making informed choices.
This article is republished from The Conversation under a Creative Commons license. For further information, readers can explore the original article.
