Scalding hot tea significantly increases the risk of developing esophageal cancer, warn researchers.
Findings in the International Journal of Cancer reinforce earlier research linking the consumption of tea, water, coffee, cocoa, and herbal infusions at temperatures above 140oF (60oC) to cancers of the throat. Water boils at 212oF (100oC).
Drinking two cups (700ml) per day at very high temperatures was associated with a 90% increase in the likelihood of developing esophageal squamous cell carcinoma (ESCC). Only 20% of those diagnosed with esophageal cancer go on to live five years.
The analysis is from a 10-year study of 50,000 adults aged 40 to 75 (at baseline). The participants live in Golestan Province in northeastern Iran, a part of the world where tea is consumed well above room temperature. The Golestan Cohort Study identified 317 newly diagnosed cases of ESCC during the period 2004-17.
At the onset of the study participants were divided into three groups: those who drank their tea very hot, those who drank their tea hot (below 140oF), and those who drank their tea lukewarm. After 10 years of follow up “very hot” tea drinkers were 2.41 times more likely to develop throat cancers compared to those who prefer hot or lukewarm tea. Those who reported drinking tea within 2 minutes of pouring were 1.51 times more likely to develop ESCC compared to those who allowed the tea to cool at least 6 minutes.
During the testing phase, participants poured two cups of tea, one to drink and the second to measure temperature at the time they drank the first cup.
“No study has previously examined this association using prospectively and objectively measured tea drinking temperature,” writes lead researcher Dr. Farhad Islami, the strategic director of Cancer Surveillance Research at the American Cancer Society. While population based studies only reveal conditions associated with the hypothesis but “our results substantially strengthen the existing evidence supporting an association between hot beverage drinking and [esophageal cancer risk],” conclude the researchers.
Islami said that “to our knowledge, this is the only large‐scale prospective study in the world in which actual tea drinking temperature has been measured by trained staff at baseline. Three independent measures of hot tea consumption were each associated with higher risk of ESCC, providing strong evidence for an association between hot beverage drinking and ESCC,” he said.
There is no known health benefit to drinking very hot beverages and since people who drink very hot beverages “can increase the risk of esophageal cancer, it is, therefore, advisable to wait until hot beverages cool down before drinking,” concludes Islami.