A Beloved Ritual Under Scrutiny
The simple pleasure of a hot drink is a cherished part of daily life across the globe. In India, the culture of 'garam chai' is deeply ingrained. However, this comforting habit has come under scientific scrutiny, not for the contents of the cup, but for its
temperature. In 2016, the World Health Organization's International Agency for Research on Cancer (IARC) made a significant classification: drinking beverages hotter than 65°C (149°F) is “probably carcinogenic to humans”. This conclusion was not about coffee or tea themselves—which are not classified as carcinogenic—but specifically about the thermal injury that very hot liquids can cause to the body. This has prompted a closer look at our daily habits and whether we need to let our beloved drinks cool down just a little before sipping.
The Science of Thermal Injury
The primary concern lies with the oesophagus, the muscular tube that carries food and drink from your throat to your stomach. When you repeatedly consume liquids at scalding temperatures, you risk causing thermal injury to the delicate cells lining this passage. Think of it like a recurring burn. This repeated damage can trigger a state of chronic inflammation. Over many years, the constant cycle of injury and repair can lead to changes in the cells' DNA, potentially increasing the risk of developing a specific type of cancer known as oesophageal squamous cell carcinoma (ESCC). Studies have shown a consistent link between the consumption of very hot beverages and a higher risk of ESCC, particularly in regions where drinking tea or other infusions at around 70°C is common. It’s important to note this risk is distinct from oesophageal adenocarcinoma, another common type, which is more strongly linked to factors like acid reflux and obesity.
How Hot is Too Hot?
The critical threshold identified by the IARC is 65°C (149°F). To put that in perspective, water boils at 100°C, and a freshly brewed cup of tea or coffee can easily be between 70°C and 95°C. Many people drink their beverages well within this potentially hazardous range. While you don’t need a thermometer for every cup, there are simple sensory cues. If a drink is too hot to sip comfortably, causes a slight burning sensation, or if you have to blow on it repeatedly before you can drink it, it’s likely above the recommended temperature. The goal isn’t to drink your beverages cold, but to allow them to cool to a warm, comfortable temperature that doesn't scald your mouth or throat. Studies have shown that even a few minutes can make a significant difference, bringing the liquid down to a safer level below 60°C.
Simple Adjustments for Safer Sipping
The good news is that reducing this risk doesn't require giving up your favourite hot drinks. It simply involves a minor adjustment to your routine. The most straightforward strategy is patience: just wait a few minutes after pouring your tea or coffee before you start drinking. This allows the temperature to drop naturally. Adding a splash of cold milk or water can also quickly bring the beverage to a safer temperature. Another helpful habit is to test the drink with a small sip before taking a large gulp. Recent research reinforces this, with a large UK-based study finding that individuals who drank their beverages 'very hot' had a threefold higher risk of oesophageal SCC compared to those who drank them 'warm'. This highlights that a small change in habit, consistently applied, can have a meaningful impact on long-term health. The focus is on moderating the temperature, not eliminating the ritual.
