Concerns regarding the consumption of hot beverages have resurfaced, with significant implications for public health. Recent studies have identified a potential link between very hot drinks and an increased risk of oesophageal cancer. The International Agency for Research on Cancer classified drinking beverages above 65°C as “probably carcinogenic to humans,” placing this risk alongside other health hazards such as indoor wood smoke emissions and high red meat consumption.
Research has primarily focused on the correlation between hot drinks and oesophageal cancer. In 2016, studies in South America revealed a notable association between the consumption of maté, a traditional herbal drink often enjoyed at temperatures around 70°C, and higher risks of developing this type of cancer. Similar findings from regions in the Middle East, Africa, and Asia have further supported this connection, although substantial research in European and Western populations had been limited until recently.
A recent comprehensive study in the United Kingdom involving nearly half a million adults confirmed that those consuming large quantities of very hot drinks, such as tea and coffee, were at an elevated risk of developing oesophageal cancer. Specifically, individuals who drank eight or more cups of very hot beverages daily were found to be nearly six times more likely to be diagnosed compared to those who abstained from such drinks.
The mechanism behind this increased risk appears to be related to the damaging effects of very hot beverages on the oesophagus. Consuming high-temperature liquids can harm the lining of the oesophagus, potentially leading to cancer over time. Historical research dating back almost 90 years first suggested this link, and ongoing studies support the idea that heat-related injuries to the oesophagus can create a conducive environment for cancer development.
Animal studies have contributed to this understanding. One significant study in 2016 observed that mice predisposed to cancer developed precancerous growths more rapidly when exposed to water at 70°C compared to those given cooler water. Another theory posits that thermal damage to the oesophageal lining may weaken its protective barrier, increasing vulnerability to gastric acid reflux, which can further exacerbate the risk of cancer.
The quantity and rate of hot beverage consumption also play crucial roles in determining cancer risk. Research indicates that consuming large sips can lead to substantial heat injuries in the oesophagus. A study measuring oesophageal temperatures in individuals drinking coffee demonstrated that a single large sip (around 20 millilitres) of 65°C coffee could raise the internal temperature by as much as 12°C. This sustained exposure to heat could result in chronic injury over time, elevating the likelihood of cancer development. In contrast, small sips are less likely to cause harm and are advisable for testing drink temperature.
Given the high brewing temperatures commonly associated with coffee and other beverages—often approaching boiling point—researchers have suggested optimal drinking temperatures for safety. A study from the United States recommended an ideal coffee temperature of 57.8°C to balance flavour and minimise heat-related risks.
To safely enjoy hot drinks, take time to let them cool before consumption. Research indicates that a hot drink can cool by 10–15°C within five minutes. Additional methods to cool beverages include stirring, blowing on them, or removing the lid from takeaway cups, which can enhance cooling rates. Incorporating cooler ingredients like milk or water can also help reduce temperatures.
As highlighted by Vincent Ho, a prominent researcher in this field, understanding the potential health implications of hot beverages is crucial. He has no relevant affiliations that would influence this discussion, ensuring objectivity in conveying these findings. The ongoing research serves as a reminder to approach hot drink consumption with caution, balancing enjoyment with awareness of possible health consequences.
