NEW YORK (CNN) – Many people start the day with a cup of tea. But those who drink it hot could increase the risk of esophageal cancer, according to a new study.
The researchers found that tea drinkers who liked their drink were warmer than 60 degrees Celsius (140 degrees Fahrenheit) and consumed more than 700 ml of tea a day – about two large cups– had a 90% greater risk of esophageal cancer, compared to those who drank less tea and at cooler temperatures.
The study examined more than 50,000 people in the Golestan, a province in the north-east of Iran.
"Many people like to drink tea, coffee or other hot drinks, but according to our report, drinking a lot of hot tea can increase the risk of esophageal cancer, so it is advisable to wait for the hot drinks to cool before drinking," said Dr. Farhad Islami, of the American Cancer Society and lead author of the study.
Previous research has found a link between the consumption of hot tea and esophageal cancer. This study, published Wednesday in the International Journal of Cancer, was the first to identify a specific temperature, according to the authors.
Esophageal cancer is the eighth most common cancer in the world and is often fatal, killing about 400,000 people each year, according to the International Agency for Research on Cancer. It is usually caused by repeated lesions of the esophagus due to smoking, alcohol, acid reflux and – perhaps – hot liquids.
The esophagus is a long tube through which to swallow food and liquids to reach the stomach.
The American Cancer Society estimates that 13,750 new cases of esophageal cancer will be diagnosed in men and 3,900 new cases in women in the United States in 2019.
The research team followed 50,045 people, aged between 40 and 75, for an average of 10 years. Between 2004 and 2017, researchers detected 317 new cases of esophageal cancer.
The study stated that more research is needed as to why the consumption of very hot tea is associated with the highest risk of esophageal cancer.
Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, said it was the heat that was the problem rather than the type of drink.
"Actually, it's probably something hot: microwave jam has been known to cause oesophageal injury. It is possible that the trauma could lead to cellular changes and therefore cancer," he told the Science Media Center. Evans was not involved in the study.
In the United States and Europe, tea is rarely consumed at temperatures above 65 degrees Celsius (149 degrees Fahrenheit), but in places like Russia, Iran, Turkey and South America, it is common to drink hot tea or even hotter.
"If you go to the Middle East or Russia, they drink it from a samovar that is constantly under heat," said Peter Goggi, president of the United States Tea Association at CNN last year. "It's very, very hot."
The dott. James Doidge, associate researcher at University College London, said that hot drinks were an established risk factor for esophageal cancer.
"It does not take a scientist to appreciate that the repeated irritation of any body surface increases the risk of cancer. Sunburn gives us skin cancer, smoking gives us lung cancer and many foods and drinks contribute to the risk of Gastrointestinal tumors, "Doidge, who was not involved in the research, said at the Science Media Center.
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