The WHO International Agency for Research on Cancer’s Monographs programme has evaluated the potential carcinogenicity of drinking coffee, maté and very hot beverages.
Oesophageal cancer is the eighth most common cause of cancer worldwide and one of the main causes of cancer death, with approximately 400 000 deaths recorded in 2012 (5% of all cancer deaths).
Very hot beverages: “Very hot” refers to any beverages consumed at a temperature above 65 °C.
Mate: Maté is an infusion made from dried leaves of Ilex paraguariensis. It is consumed mainly in South America and to a lesser extent in the Middle East, Europe, and North America. Maté is traditionally drunk very hot (at about 70 °C), but it may also be consumed warm or cold.
Very hot beverages
Drinking very hot beverages was classified as probably carcinogenic to humans (Group 2A).
This was based on limited evidence from epidemiological studies that showed positive associations between cancer of the oesophagus and drinking very hot beverages.
It was found that the risk of developing oesophageal cancer increased with the temperature at which the beverage was drunk.
In experiments involving animals, there was also limited evidence for the carcinogenicity of very hot water.
Cold maté did not have carcinogenic effects in experiments on animals or in epidemiological studies.
Therefore, drinking maté at temperatures that are not very hot was not classifiable as to its carcinogenicity to humans (Group 3).
This was based on inadequate evidence in humans and experimental animals.
Drinking coffee was not classifiable as to its carcinogenicity to humans (Group 3).
After thoroughly reviewing more than 1000 studies in humans and animals, the Working Group found that there was inadequate evidence for the carcinogenicity of coffee drinking overall.
Many epidemiological studies showed that coffee drinking had no carcinogenic effects for cancers of the pancreas, female breast, and prostate, and reduced risks were seen for cancers of the liver and uterine endometrium.
For more than 20 other cancers, the evidence was inconclusive.
WHO’s recommendation: Do not consume very hot beverages- allow them to cool down sufficiently before consumption.
Link to the IARC press release:
Link to the full article in The Lancet Oncology (free, but requires registration):
Link to WHO’s Technical Report Series providing advice on diet, nutrition, and prevention of chronic diseases (2003):