Research involving more than 454,000 UK adults found higher rates of one form of esophageal cancer among people who regularly drank very hot beverages. Scientists say temperature, rather than tea or coffee itself, may be the important factor.
Drinking tea or coffee at very high temperatures may increase the risk of developing a particular type of esophageal cancer, according to a large study involving more than 454,000 adults in the United Kingdom. Researchers found that people who preferred very hot beverages had higher rates of esophageal squamous cell carcinoma, especially when they consumed several cups each day.
The findings were published on February 19, 2025, in the British Journal of Cancer. The study adds to evidence that repeated exposure to extremely hot liquids may damage the lining of the esophagus, the muscular tube connecting the throat to the stomach.
The concern is primarily the temperature of the drink, not whether it contains tea or coffee. Researchers found similar patterns among people consuming either beverage, suggesting that repeated exposure to heat may explain the association.
The results support earlier warnings from the World Health Organization’s International Agency for Research on Cancer (IARC). In 2016, the agency classified drinking beverages hotter than 149 degrees Fahrenheit (65 degrees Celsius) as probably carcinogenic to humans.
However, scientists emphasize that the research does not mean drinking ordinary hot coffee or tea will cause cancer. The study was observational, and the overall likelihood of developing this particular cancer remained low among participants.
Study Followed More Than 454,000 Adults
Researchers analyzed health and dietary information from 454,796 participants in the UK Biobank, a long-running project that examines the relationships between lifestyle, genetics and disease.
Participants reported how much tea and coffee they normally consumed and whether they preferred their drinks warm, hot or very hot. Their responses were compared with cancer diagnoses recorded during an average follow-up period of 11.6 years.
During that period, researchers identified 242 cases of esophageal squamous cell carcinoma and 710 cases of esophageal adenocarcinoma, the two major forms of esophageal cancer.
The distinction between these cancers matters because they develop from different types of cells and have different risk factors.
Squamous cell carcinoma develops from the flat cells lining the esophagus. Adenocarcinoma usually develops in the lower esophagus and is more strongly associated with conditions such as chronic acid reflux and Barrett’s esophagus.
The study found a clear association between hotter beverages and squamous cell carcinoma, but not adenocarcinoma.
Researchers adjusted their calculations for several potential influences, including age, smoking, alcohol consumption, body weight and other lifestyle characteristics.
Although these adjustments strengthened the findings, they could not eliminate every possible difference between participants.
Cancer Risk Increased With Hotter Drinks and More Cups
The results showed that both drinking temperature and daily consumption were associated with increased relative risk.
Compared with participants who avoided tea and coffee or preferred their beverages warm, people drinking four to six cups of hot beverages daily had nearly twice the risk of squamous cell carcinoma.
For those who preferred very hot drinks, the association was stronger.
Participants who consumed up to four cups of very hot tea or coffee daily had approximately 2.5 times the risk of developing the disease compared with the reference group.
Among people drinking more than eight cups of very hot beverages daily, the estimated relative risk was approximately 5.6 times higher.
The pattern suggested that greater exposure to heat, whether through higher temperatures or more frequent drinking, was associated with increased cancer incidence.
However, these findings describe relative risk rather than the absolute probability of developing cancer.
For example, a fivefold increase in the risk of an uncommon disease does not mean that five out of every ten people exposed will develop it. It means the estimated rate is five times that of the comparison group.
Only 242 participants developed squamous cell carcinoma during the study, representing approximately 0.05 percent of the entire study population. Individual risk varied across different groups.
The researchers also reported considerable uncertainty around some estimates because relatively few participants developed the disease.
Why Extremely Hot Drinks May Cause Damage
Scientists believe that repeated exposure to very hot liquids could injure the cells lining the esophagus.
The esophagus is covered by delicate tissue that comes into direct contact with food and beverages as they travel toward the stomach.
When a drink is extremely hot, it can cause thermal injury to this lining. Although damaged cells can repair themselves, repeated injury may contribute to changes associated with cancer development.
One proposed explanation is that chronic inflammation and repeated cell replacement create conditions in which abnormal cells may develop.
Researchers have not established every biological step connecting heat exposure to cancer. However, experiments involving animals have supported the possibility that very hot liquids can promote tumor development under certain conditions.
The IARC considered human studies and animal evidence when it classified very hot beverage consumption as probably carcinogenic in 2016.
That classification concerns the potential hazard of an exposure. It does not provide an individual’s probability of developing cancer or establish that every exposure will lead to disease.
What Temperature Is Considered Too Hot?
The IARC identifies beverages consumed above 149 degrees Fahrenheit, or 65 degrees Celsius, as very hot.
That is substantially below the boiling point of water, which is approximately 212 degrees Fahrenheit at sea level.
Tea and coffee may initially be prepared using water close to boiling, but the temperature generally falls before and during consumption.
A beverage’s preparation temperature is not necessarily the temperature at which someone drinks it.
The UK Biobank study did not directly measure the temperature of each participant’s drinks. Instead, participants selected descriptions such as warm, hot or very hot.
Researchers acknowledged that these descriptions can vary between individuals. One person’s idea of a hot drink may be considerably different from another person’s.
Because actual drinking temperatures were not measured, the study cannot establish a precise temperature at which cancer risk begins increasing.
Still, the findings suggest that regularly consuming liquids hot enough to cause discomfort may be an avoidable source of exposure.
Allowing beverages to cool before drinking is a practical precaution. Adding milk or cool water may also lower the temperature, although the study did not test these practices as cancer-prevention measures.
Smoking and Alcohol Remain Important Risk Factors
Doctors emphasize that beverage temperature is only one potential factor associated with esophageal cancer.
Tobacco use and heavy alcohol consumption are established risk factors for squamous cell carcinoma. Their effects are particularly important when evaluating a person’s overall risk.
Researchers included smoking and drinking habits in their statistical analysis to reduce the possibility that these factors explained the observed association with beverage temperature.
Other characteristics, including age, nutrition and general health, can also influence cancer risk.
For esophageal adenocarcinoma, chronic acid reflux, Barrett’s esophagus and obesity are especially relevant risk factors.
The UK study did not find consistent evidence that drinking hotter beverages increased the incidence of adenocarcinoma.
This difference suggests that the two forms of cancer should not be treated as interchangeable when discussing the health effects of hot drinks.
Important Limitations of the Research
The study’s large population and lengthy follow-up period were major strengths. However, its observational design means researchers could identify associations without demonstrating direct cause and effect.
Participants reported their drinking habits at the beginning of the investigation, and their preferences could have changed over the following years.
The researchers also relied on subjective temperature categories rather than direct measurements of drinking temperatures.
Another limitation was the relatively small number of squamous cell carcinoma cases. Although the overall participant population was large, the number of cancer diagnoses within individual consumption groups was much smaller.
That made some estimates less precise and increased the importance of considering the full range of statistical uncertainty.
The researchers also acknowledged that lifestyle factors not fully captured in their analysis could have influenced the results.
Even so, the findings are consistent with earlier investigations involving very hot tea and maté consumption in Iran, South America and parts of Asia.
What Tea and Coffee Drinkers Should Know
The findings do not suggest that people need to stop drinking tea or coffee.
Previous research has associated moderate consumption of these beverages with several favorable health outcomes, although those studies also have limitations.
The concern identified by the UK researchers involves repeated consumption at high temperatures, particularly when combined with large daily quantities.
For people who enjoy several cups throughout the day, allowing each drink to cool before taking the first sip may help reduce unnecessary exposure to intense heat.
There is no established waiting period that guarantees a beverage has reached a safer temperature. Cooling time depends on the starting temperature, cup size, container and surrounding conditions.
People who regularly experience difficulty swallowing, persistent pain when swallowing, unexplained weight loss or other concerning symptoms should seek medical evaluation rather than assuming hot beverages are responsible.
The study’s central finding is that beverage temperature deserves attention alongside more familiar cancer risk factors. Researchers found a consistent association with squamous cell carcinoma, but further investigation is needed to determine how much cooling beverages reduces a person’s long-term risk.
IMAGE: Source Own work Author Ekaterina Kvelidze CC4