The Real Issue: It's the Heat, Not the Habit
The concern raised by scientists isn't about tea or coffee themselves. In fact, when consumed at safe temperatures, coffee has been cleared of previous cancer concerns. The issue is thermal injury. The International Agency for Research on Cancer (IARC),
a part of the World Health Organization, has classified drinking beverages hotter than 65°C (149°F) as "probably carcinogenic to humans." This is because repeatedly exposing the delicate lining of your oesophagus—the tube that carries food from your throat to your stomach—to scalding liquids can cause chronic inflammation and cellular damage.
Understanding Oesophageal Heat Stress
Think of it like a persistent, low-grade burn. Each time you swallow a liquid that's too hot, you cause minor damage to the cells lining the oesophagus. Your body constantly works to repair this damage. Over many years of this repeated injury-and-repair cycle, the process can sometimes go wrong, increasing the chances of abnormal cell development that may lead to cancer. Studies have shown this risk is particularly for oesophageal squamous cell carcinoma, a specific type of oesophageal cancer. While the overall risk for any single individual remains relatively low, the habit is so widespread, particularly in tea-loving nations like India, that it is a public health consideration.
How Hot is Too Hot?
The 65°C threshold identified by the IARC is a key marker. To put that in perspective, a freshly boiled kettle produces water at 100°C. Even after being poured, a cup of black tea or coffee can easily remain above 70°C for several minutes. You don't need a thermometer to check every cup. A good rule of thumb is if the cup is too hot to hold comfortably or if a sip makes you wince, it's too hot to drink. A drink at a safe temperature should feel warm, not scalding.
A Guide to Safer Sipping
The good news is that you don't need to give up your beloved chai or coffee. Simple adjustments are all it takes to significantly lower any potential risk. The most effective strategy is also the easiest: just wait. Letting your drink cool for a few minutes before you start sipping can drop the temperature into a safer range. Adding milk or using a wider-mouthed mug, which increases the surface area, can also help dissipate heat faster. The goal is to turn a scalding drink into a pleasantly warm one. One American study aimed at balancing safety and enjoyment suggested an optimal drinking temperature of around 58°C.
Context is Key: Other Risk Factors
It's important to remember that very hot drinks are considered a contributing risk factor, not a sole cause. The risk of oesophageal cancer is substantially higher for individuals who also use tobacco or drink alcohol. In India, tobacco use (both smoked and chewed), alcohol consumption, and certain dietary patterns are also recognised as major risk factors for oesophageal cancer. Therefore, while letting your tea cool is a wise move, addressing these other lifestyle factors is even more critical for reducing your overall cancer risk.
