From an evidence perspective, the key point comes from a striking classification by the International Agency for Research on Cancer (IARC). In 2016, IARC classified the act of drinking very hot drinks (above 65 degrees Celsius) as “possibly carcinogenic to humans.”
In South America, where the habit of drinking maté - a herbal tea - at around 70 degrees Celsius is quite common, many studies here also show that people who drink very hot maté have a higher rate of esophageal cancer.
Similar trends were noted in the Middle East, Africa and Asia, reinforcing the link between beverage temperature and esophageal cancer.
In Iran, a study following more than 50,000 people found that drinking 700 ml of tea at 60 degrees Celsius or above per day could increase the risk of esophageal cancer by 90% compared to people who drank the beverage at lower temperatures.
Drinking very hot drinks can increase the risk of esophageal cancer (Photo: Saily Sabah).
A study of nearly half a million adults in the UK also found that people who drank a lot of “very hot” tea or coffee had a significantly higher risk of esophageal cancer. Those who drank eight or more cups a day had a risk nearly six times higher than those who did not drink hot drinks.
Scientists have explained the mechanism for this nearly 90 years. Excessive heat can burn the small cells in the lining of the esophagus. When this surface is constantly exposed to heat, the cells have to speed up their regeneration to heal. Prolonged repair in a chronically inflamed environment increases the risk of genetic errors, paving the way for cancer.
Animal experiments support this hypothesis. In cancer-prone mice, 70°C water promoted the appearance and progression of precancerous lesions in the esophagus more rapidly than warm water.
In addition, when the mucosa is weakened by heat, refluxed gastric acid has the opportunity to "reinforce", worsening the damage and maintaining the cycle of inflammation - regeneration - damage.
Remarkably, risk is not only determined by the number on the thermometer, but also by how we drink.
A study that directly measured the temperature inside the esophagus while participants drank coffee suggests that sip size may be more important than the temperature of the beverage itself.
Specifically, a large gulp of about 20 ml of coffee at 65 degrees Celsius can cause the temperature in the esophagus to spike by up to 12 degrees Celsius. This shows that “gulp” transfers more heat than “sip”. Therefore, drinking large gulps of hot drinks over a long period of time is the cause for concern.
A few sips of 65-degree coffee won’t cause any immediate problems. But the habit of drinking large amounts of very hot drinks, day after day, is what increases the risk of esophageal cancer.
So what is the safe threshold? A study in the US calculated the ideal temperature for coffee to retain its flavor without damaging the esophagus and came up with a result of about 57.8 degrees Celsius. This number is not an absolute temperature standard for all drinks, but it can be a useful reference.
However, scientists also note that esophageal cancer is not a common type of cancer. Drinking "super hot" drinks can increase the risk of this cancer if the drinker has the habit of smoking, abusing alcohol or is obese, or has gastroesophageal reflux disease.
Source: https://dantri.com.vn/suc-khoe/su-that-uong-do-sieu-nong-gay-ung-thu-20250822011156587.htm
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