NEW YORK (CNN) – Many people start their day with a cup of tea. But those who drink hot may increase the risk of oesophageal cancer, according to a new study.
The researchers found that tea drinkers who drink more than 60 degrees Celsius consumed more than 700 ml of tea per day – about two large cups– had a 90% higher risk of esophageal cancer compared to those who drank less tea and at cooler temperatures.
The study looked at more than 50,000 people in Golestan, a province in northeastern Iran.
"Many people like to drink tea, coffee, or other hot drinks, but drinking hot tea, according to our report, can increase the risk of esophageal cancer, so it's advisable to wait for hot drinks to cool down before drinking." Dr. Farhad Islami of the American Cancer Society and lead author of the study.
Previous research has found a link between drinking hot tea and esophageal cancer. This study, published Wednesday in the International Journal of Cancer, was the first to establish a specific temperature, according to the authors.
Esophageal cancer is the eighth most common cancer in the world and is often fatal. According to the International Agency for Research on Cancer, about 400,000 people die every year. It is usually caused by repeated esophageal injury from smoke, alcohol, acid reflux, and possibly hot fluids.
The esophagus is a long tube through which swallowed food and fluids enter the stomach.
The American Cancer Society estimates that in 2019, 13,750 new cases of esophageal cancer in men and 3,900 new cases in women will be diagnosed in the United States.
The research team followed an average of 50,045 people between the ages of 40 and 75 for 10 years. Between 2004 and 2017, researchers discovered 317 new cases of esophageal cancer.
The study said more research was needed as to why drinking very hot tea is associated with the higher risk of esophageal cancer.
Stephen Evans, Professor of Pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, said that it was not the type of drink but the heat.
"In fact, it's probably a bit hot: microwaved jam is known to cause esophageal injury, and it's possible that the trauma leads to cell changes and therefore cancer," he told the Science Media Center. Evans was not involved in the study.
In the US and Europe, tea is rarely consumed at temperatures above 65 degrees Celsius. In areas like Russia, Iran, Turkey and South America it is common to drink hot or even hot tea.
"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 Tea Association of the United States, to CNN last year. "It's very, very hot."
Dr. James Doidge, senior research associate at University College London, said hot drinks are an established risk factor for esophageal cancer.
"It does not take a scientist to realize that repeated irritation of a body surface increases cancer risk, sunburns give us skin cancer, smoking brings lung cancer, and many foods and drinks contribute to the risk of gastrointestinal cancer." Doidge, who was not involved in the research, said the Science Media Center.
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