By Emma Sage, SCAA Coffee Science Manager
The World Health Organization’s International Agency for Research on Cancer (IARC) has announced that they are re-classifying coffee from a “group 2B” to a “group 3” substance (Loomis and others 2016). This means that coffee is in the clear and is no longer officially linked with being a possible carcinogen.
The IARC panel of expert doctors and scientists has been reviewing coffee, mate, and very hot beverages since May of this year. This review was to follow-up on the classification of these beverages over 25 years ago. Since 1991, coffee had been classified by IARC as “possibly carcinogenic” (group 2B) (International Agency for Research on Cancer 1991). For this re-evaluation, a much larger database of more than 1000 studies were available. Today, that classification has been updated to reflect new, better evidence on bladder cancer and over 20 other forms of cancer. This change means that coffee is no longer classified as a carcinogen (group 3). This is a rare reversal of the IARC panel’s decision, who has never previously positively reclassified any foodstuff or beverage. Go coffee!
One caveat of this decision was that hot beverages were classified as group 2A, probably carcinogenic and linked to oesophageal cancer in humans. This refers other beverages when consumed at very hot (think scalding) temperature. Despite the fact that coffee is not included in this evaluation of hot beverages, this means a common sense approach to drinking and serving coffee is nonetheless to our benefit. We all can easily avoid this potential risk by letting hot beverages cool off for a few minutes. Studies have demonstrated that coffee consumers prefer to consume coffee around 60°C/140°F (Lee and O’Mahony 2002; Borchgrevink and others 1999). This is below the temperature cited by the IARC panel for hot beverages as group 2A (Loomis and others 2016), and likely the comfortable temperature where most consumers drink their coffee.
We all know that nothing changed about your coffee between yesterday and today. This IARC decision simply follows the overwhelming flow of evidence from years’ of scientific research into the topics of coffee, health, and cancer. In fact, the expert IARC panel determined that regularly drinking coffee could actually help protect against some types of cancer, and has strong anti-oxidant effects (Loomis and others 2016). It is the good news on coffee that we have been learning and will continue to learn more about as the research moved forward.
Today is a great day for coffee! So enjoy it, for all the reasons you love it, and (continue to) know that it will not cause cancer.
Quick answers to questions you or your customers might have:
Q: So, does this mean coffee doesn’t cause cancer?
A: This means that the World Health Organization has classified coffee into group 3. Technically, this means that coffee was found to be not classifiable as to its carcinogenicity to humans. However, the IARC expert panel was able to conclude that coffee is unlikely to causes cancers of the breast, prostate, and pancreas. In addition, they concluded that that coffee helps prevent liver and uterine endometrium cancers. For over 20 other types of cancer, IARC panel concluded that there was inadequate information to enable a conclusion on this matter.
Q: But what about this thing about hot coffee causing cancer?
A: The possible connection between hot liquids and specific cancer applies to certain liquids only, and did not include coffee. This was based on limited evidence from epidemiological studies that showed positive associations between cancer of the esophagus and drinking very hot beverages, it only applies to very hot liquids, hotter than most people consume coffee.
IARC Q&A on coffee review: http://www.iarc.fr/en/media-centre/iarcnews/pdf/Monographs-Q&A_Vol116.pdf
The Lancet Oncology paper by Loomis and others: http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(16)30239-X/fulltext
Borchgrevink CP, Susskind AM, Tarras JM. 1999. Consumer preferred hot beverage temperatures. Food Quality and Preference 10(2):117-21.
International Agency for Research on Cancer WHO. 1991. Coffee, tea, mate, methylxanthines and ethylglyoxal. IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. IARC Monogr Eval Carcinog Risks Hum 51:1-513.
Lee HS, O’Mahony M. 2002. At What Temperatures Do Consumers Like to Drink Coffee?: Mixing Methods. J. Food Sci. 67(7):2774-7.
Loomis D, Guyton KZ, Grosse Y, Lauby-Secretan B, El Ghissassi F, Bouvard V, Benbrahim-Tallaa L, Guha N, Mattock H, Straif K. 2016. Carcinogenicity of drinking coffee, mate, and very hot beverages. The Lancet Oncology.