Individuals who drink scalding hot tea may have as much as eight times the risk of developing esophageal cancer compared with individuals who consume their tea warm or lukewarm. The results of this study were published in the British Medical Journal.
The esophagus is a tube that carries food from the mouth to the stomach. Esophageal cancer is relatively uncommon but is one of the most aggressive and deadly forms of cancer. Some regions have higher rates of esophageal cancer, including Asia, South America, and Africa.
The Golestan Province in northern Iran has an unusually high rate of esophageal cancer; individuals who live in the region have a 20-25% chance of developing the disease. However, two of the common risk factors associated with esophageal cancer—smoking and alcohol—are relatively uncommon in the region. Tea drinking in this region, however, is unique because hot tea is virtually the only beverage available and it is consumed scalding hot and black (without any cream or sugar).
Thus, researchers in Iran conducted two studies to evaluate the link between the consumption of hot tea and the rate of esophageal cancer. In the cohort study, the researchers served tea to 48,582 participants who indicated their temperature preference, which was then checked by digital thermometer. They found that 39% preferred their tea below 60 degrees Celsius (140 degrees Fahrenheit), 39% preferred it between 60-64 degrees Celsius (140-147 degrees Fahrenheit), and 22% preferred it at 65 degrees Celsius (149 degrees Fahrenheit) or higher.
The case-control study included 300 people with esophageal squamous cell carcinoma and 571 matched controls who answered questions about their tea drinking habits including their preferred temperature (very hot, hot, warm, or lukewarm) as well as how long they brewed the tea prior to drinking it. The results indicated that individuals who drank their tea “very hot” (above 70 degrees Celsius, 158 degrees Fahrenheit) were eight times more likely to develop esophageal cancer compared with their counterparts who consumed tea that was warm or lukewarm (below 65 degrees Celsius, 149 degrees Fahrenheit). Those who simply preferred their tea “hot” (65 degrees Celsius, 149 degrees Fahrenheit) were two times more likely to develop esophageal cancer than those who drank warm or lukewarm tea.
In addition, the researchers found that individuals who consumed their tea less than two minutes after pouring it had five times the risk of esophageal cancer compared with those who waited four minutes or longer.
The researchers concluded that drinking hot tea is strongly associated with an increased risk of esophageal cancer. They believe that the temperature is the problem, not the tea, and they speculated that perhaps the scalding liquid damages the mucosal lining of the throat in some way that then allows esophageal cancer to develop. Research will likely be ongoing to evaluate the relationship between hot tea and esophageal cancer. In the meantime, the researchers suggest that tea drinkers simply allow their tea to sit four minutes or longer before drinking it.
 Islami F, Pourshams A, Nasrollahzadeh D, et al. Tea drinking habits and oesophageal cancer in a high risk area in northern Iran: Population based case-control study. British Medical Journal. 2009; 338: b929.