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Friday 28th October 2016

Cancer link to steaming hot tea

30th March 2009

Iranian researchers have found that drinking scalding hot or very hot tea may increase the risk of a certain type of cancer.


The findings, published in the BMJ, formerly known as the British Medical Journal, looked at a group of tea drinkers in an area of Iran where oesophageal squamous cell carcinoma is unusually prevalent.

Researchers studied tea drinkers in the northern province of Golestan. While oesophageal squamous cell carcinoma is the most common kind, it is adenocarcinoma of the oesophagus which is on the rise in Western countries.

Most Iranians drink tea daily, and some oesophageal cancer risk factors like smoking are less prevalent.

Led by Tehran University of Medical Sciences research fellow Farhad Islami, researchers interviewed 300 people with confirmed cases of esophageal squamous cell carcinoma, as well as 571 healthy people of similar background.

Participants were quizzed about about whether they usually drank their tea very hot, hot, warm, or lukewarm, and how long they let the tea brew before drinking it.

Almost all participants drank black tea daily. But cancer of the oesophagus was less common among people who drank their tea warm or lukewarm, and eight times as common among drinkers of "very hot" tea compared with the control group who had no oesophageal cancer.

Meanwhile, hot tea drinkers were twice as likely as warm or lukewarm tea drinkers to have oesophageal cancer.

while the findings held after adjustments were made for other risk factors, researchers were concerned that a judgment about what is "hot" or "lukewarm" was highly subjective.

They measured, using a digital thermometer, the temperature of tea drunk by more than 48,000 local people who indicated their preferred tea temperature.

They found that 39% drank their tea at temperatures less than 60 degrees Celsius (140 degrees Fahrenheit), 39% drank their tea at 60-64 degrees Celsius (140-147 degrees Fahrenheit), and 22% drank their tea at 65 degrees Celsius (149 degrees Fahrenheit) or higher.

The possible link between hot drinks and oesophageal cancer risk is not a new one, and it is impossible to tell from this study whether the effects are linked only to hot tea, or to hot drinks of any kind.

Oesophageal cancer has been linked to drinking hot mate, a local brew consumed at almost boiling temperature, in Argentina, for example.

The problems were caused by chronic inflammation in the lining of the oesophagus, experts said.

Islami's team said too-hot liquid could injure oesophageal cells, giving cancer a chance to develop.

A BMJ editorial said Islami's study was compelling and relevant to clinicians and researchers in many settings.

While more studies were needed, experts said that letting hot drinks cool off for several minutes was a good idea, with few adverse consequences likely.

But the study's findings should not put people off the time-honoured ritual of drinking tea, the BMJ editorial added.

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