Steaming hot tea linked to cancer

Drinking steaming hot tea has been linked with an increased risk of oesophageal (food tube) cancer, Iranian scientists have found.The British Medical Journal study found that drinking black tea at temperatures of 70C or higher increased the risk.Experts said the finding could explain the increased oesophageal cancer risk in some non-Western populations.

Adding milk, as most tea drinkers in Western countries do, cools the drink enough to eliminate the risk.The oesophagus is the muscular tube that carries food from the throat to the stomach.Oesophagus cancers kill more than 500,000 people worldwide each year and oesophageal squamous cell carcinoma (OSCC) is the commonest type.

Tobacco and alcohol are the main factors linked to the development of oesophageal cancers in Europe and America nations.But it has not been clear why other populations around the world have high rates of the disease although there has been a theory that regularly drinking very hot drinks damage the lining of the gullet.

Golestan Province in northern Iran has one of the highest rates of OSCC in the world, but rates of smoking and alcohol consumption are low and women are as likely to have a diagnosis as men. Tea drinking, however, is widespread.The University of Tehran researchers studied tea drinking habits among 300 people diagnosed with OSCC and compared them with a group of 570 people from the same area.Nearly all participants drank black tea regularly, on average drinking over a litre a day.

Compared with drinking warm or lukewarm tea (65C or less), drinking hot tea (65-69C) was associated with twice the risk of oesophageal cancer, and drinking very hot tea (70C or more) was associated with an eight-fold increased risk.The speed with which people drank their tea was also important.Drinking a cup of tea in under two minutes straight after it was poured was associated with a five-fold higher risk of cancer compared with drinking tea four or more minutes after being poured,

There was no association between the amount of tea consumed and risk of cancer.Because the researchers had relied on study participants to say how hot their tea was, they then went on to measure the temperature of tea drunk by nearly 50,000 residents of the same area.This ranged from under 60C to more than 70C, and reported tea drinking temperature and actual temperature was found to be similar.