By Erica Mather 22/06/2016

There is no conclusive evidence that drinking coffee causes cancer, but experts report that drinking very hot beverages ‘probably’ causes cancer of the oesophagus.

The specialized cancer agency of the World Health Organization (WHO) – the International Agency for Research on Cancer (IARC), held a press call last week where they released the results of a thorough investigation of the scientific literature on drinking coffee, maté and very hot beverages.

After 25 years the cancer causing potential of drinking coffee has been re-evaluated. According to a group of 23 leading international experts, drinking coffee is “not classifiable as to its carcinogenicity to humans.” There is not enough evidence to describe it as hazardous, but neither has it been proven safe.

Drinking coffee has been linked to bladder cancer in the past and IARC classified it as as “possibly carcinogenic to humans” in 1991.  However, experts say that this correlation has become weaker and it is no longer possible to establish whether drinking coffee causes bladder cancer.

IARC Director, Dr Christopher Wild, says the findings, published in The Lancet Oncology, indicate that the temperature of drinks is more important in terms of cancer causing potential than the type of drinks themselves.

“These results suggest that drinking very hot beverages is one probable cause of oesophageal cancer and that it is the temperature, rather than the drinks themselves, that appears to be responsible.”

Drinking very hot beverages above 65 °C is classified as “probably carcinogenic to humans,” although this is based on limited evidence from epidemiological studies. While Dr Wild stresses that smoking and drinking alcohol are the leading causes of oesophageal cancer especially in high-income countries (including New Zealand), there are countries where the risk of oesophageal cancer increases with the temperature at which often traditional beverages are drunk.

Associate Professor Andrea ’t Mannetje, Centre for Public Health Research, Massey University comments:

“This is mainly relevant for those countries where tea or maté (a traditional South-American beverage) is traditionally drunk very hot, and the scalding hot drink may reach the oesophagus.”

Should we stop drinking all hot drinks? Professor Mannetje responds:

“No. The studies done to date do not suggest that drinking hot drinks in general increases the risk of cancer. However, this IARC evaluation does suggest that drinking these drinks at scalding hot temperatures should be avoided, as this probably increases the risk of cancer of the oesophagus.”

For more information on the IARC classification, read the IARC Monographs Q&A:

Read the IARC Monographs Q&A on the evaluation of drinking coffee, maté, and very hot beverages:

Featured image: CC Pixabay

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0 Responses to “The consensus on coffee and cancer”

  • I acquired my passion for coffee doing my Ph.D. Children seems to have sustained it. Fortunately both have meant I don’t think I’ve ever dunk a scalding hot coffee. Usually its cooled to room temperature before I get around to imbibing