Very Hot Tea Linked to Esophageal Cancer
Posted by medconsumers on April 1, 2009
People who drink very hot tea increase their chance of developing cancer of the esophagus, the muscular tube through which food passes from the throat to the stomach. This is the finding of a new study conducted in one province of northern Iran where people are known to drink large amounts of very hot tea because the water supply is unsafe. It is not the black tea they are drinking but its temperature that accounts for their high incidence of esophageal cancer.
The take-home message from this study: Wait four minutes or more before drinking any freshly boiled beverage.
In a recent issue of the BMJ (British Medical Journal), the lead author of this study, Resa Malekzadeh, Tehran University, and colleagues explained that their finding goes well beyond one region of one middle-eastern country. Worldwide, there are wide variations in the incidence of esophageal cancer, which suggests to cancer researchers that the disease is preventable.
Heavy alcohol and tobacco use are long known to be factors in the development of esophageal cancer and this explains why men are more likely to get esophageal cancer than women. But alcohol and tobacco are not implicated in non-Western countries with very high rates of the disease and where women are as likely as men to be diagnosed with esophageal cancer.
This made one province in northern Iran the perfect place to study another strongly suspected risk factor—drinking very hot beverages. The province has a higher rate of esophageal cancer than the rest of Iran, no gender differences in incidence, and a high intake of extremely hot tea. The investigators asked about the tea drinking habits of 300 people who were diagnosed with esophageal cancer and a control group of 571 people from the same province who were cancer-free.
To test the definitions of lukewarm, hot, and very hot, the researchers spent time measuring the actual temperature of the tea consumed by nearly 50,000 residents of the province.
The people who said that they drank their tea within two minutes after the water was boiled were five times more likely to have esophageal cancer than the people who waited four minutes or more to drink their tea.
The investigators could only guess at the reasons why. They suspect that chronic heat injury to the lining of the esophagus could cause the development of cancer. More research, they advise, should be directed to this subject.
In the editorial that accompanied this study, Australian researcher David C. Whiteman wrote that it provides “persuasive evidence” against the practice of drinking very hot tea. Whiteman also pointed out that others knew this long ago, citing the advice of Victorian cookbook writer, “Mrs Beeton, who prescribes a five to 10 minute interval between making and pouring tea, by which time the tea will be sufficiently flavorsome and unlikely to cause thermal injury.”
The first rapid response to this study (an electronic letter to the editor) came from someone in Argentina who wrote: “In Latin countries the majority of people drink black coffee, just as hot and potentially just as dangerous in terms of cancer risk. In Argentina, of course, traditionally as well as coffee, they drink maté [an herbal beverage], which is never drunk with milk and is frequently scaldingly hot.”
Maryann Napoli, Center for Medical Consumers© April 2009