Researchers from the Tehran University of Medical Sciences in Northern Iran have found a possible link between drinking very hot tea and oesophageal cancer. The group studied the tea-drinking habits of 300 people with oesophageal cancer and another 571 healthy men and women from the same area in Golestan Province in northern Iran.

The research published in the British Medical Journal found that drinking very hot tea at a temperature of greater than 70 degrees Celsius was associated with an eight-fold increased risk of throat cancer compared to sipping warm or lukewarm tea at less than 65 degrees.

Golestan Province has one of the highest rates of throat cancer in the world but smoking rates and alcohol consumption are low. Nearly all the volunteers drank black tea regularly, consuming on average more than a litre each day. People who regularly drank tea less than two minutes after pouring were five times more likely to develop the cancer compared to those who waited four or more minutes, the researchers found. It is not clear how hot tea might cause cancer but one idea is that repeated thermal injury to the lining of the throat somehow initiates it.

Previous research in to the tea drinking habits of the British found that people prefer their tea at an average temperature of 56 degrees to 60 degrees.

Research paper at BMJ