The Real Issue: Temperature, Not the Drink
For years, coffee and tea have been debated for their health impacts. However, when it comes to the risk of esophageal cancer, research points to a different culprit: temperature. The International Agency for Research on Cancer (IARC), a part of the World
Health Organization, has classified drinking very hot beverages as "probably carcinogenic to humans" (Group 2A). This conclusion isn't about the coffee or tea itself, but rather the act of consuming any liquid at scalding temperatures. Studies found no conclusive evidence that coffee itself is carcinogenic; in fact, it was downgraded to Group 3, meaning 'not classifiable'. The focus is squarely on the thermal injury caused by the heat.
What Temperature Is 'Too Hot'?
The critical threshold identified by the IARC is any beverage consumed at a temperature above 65°C (149°F). To put that in perspective, many coffee shops serve drinks between 71°C and 85°C. Studies in regions where tea is traditionally drunk at around 70°C, such as parts of Asia and South America, showed an increased risk of esophageal cancer. One study found that drinking 700ml of tea per day at 60°C or higher was associated with a 90% increased risk compared to those who drank it cooler. The simple act of waiting a few minutes for your drink to cool can significantly reduce this risk.
The Cellular Injury Process
When you drink something that is excessively hot, it causes a 'thermal injury' to the delicate lining of your esophagus. Think of it as a repeated, low-grade burn. This isn't a one-time event but a chronic stressor on the cells. Endoscopic studies of people who have ingested overly hot liquids show visible signs of this damage, including redness, blisters, and the formation of a whitish layer called a pseudomembrane, sometimes in a pattern described as a "candy-cane esophagus". This physical damage is the first step in a harmful chain reaction.
From Injury to Chronic Inflammation
Inflammation is the body's natural response to injury. When cells in the esophagus are repeatedly damaged by heat, the immune system initiates a constant inflammatory process to repair the tissue. While acute inflammation is a healthy healing mechanism, chronic inflammation is problematic. This persistent state of alert can disrupt the normal functioning of cells. Some studies suggest that the repeated cycle of injury and repair from hot liquids leads to an increased rate of cell division in the esophageal lining, which is a known factor in promoting tumour growth.
The Link to Increased Cancer Risk
Chronic inflammation is a well-known driver of cancer. Over time, the constant cellular turnover and inflammatory environment can increase the likelihood of DNA damage and mutations, potentially leading to the formation of cancerous cells. The IARC's classification is based on limited but consistent evidence from studies showing this association. It is important to note that this doesn't mean drinking a hot beverage will give you cancer. Major risk factors for esophageal cancer remain tobacco and alcohol use. However, thermal injury appears to be a contributing factor, potentially making the esophagus more vulnerable to other carcinogens.
How to Enjoy Your Drinks Safely
The good news is that this risk is easily manageable. The advice isn't to give up your favourite hot drinks, but simply to let them cool down. Waiting a few minutes before you start sipping is the most effective step you can take. You can also add a splash of cold milk or simply test the temperature before taking a big gulp. The optimal drinking temperature, where you can appreciate the flavour without the risk of scalding, is generally considered to be below 60°C. By making this small adjustment, you can continue to enjoy the comfort of a hot drink without the associated health concerns.
