Can coffee cause cancer? Only if it’s very hot, says WHO agency
There is no conclusive evidence that drinking coffee causes cancer, the World Health Organization’s cancer agency said on Wednesday in a reverse of its previous warning, but it also said all “very hot” drinks are probably carcinogenic.
The International Agency for Research on Cancer (IARC) had previously rated coffee as “possibly carcinogenic” but has changed its mind.
It now says its latest review found “no conclusive evidence for a carcinogenic effect” of coffee drinking and pointed to some studies showing coffee may actually reduce the risk of developing certain types of cancer. “(This) does not show that coffee is certainly safe ... but there is less reason for concern today than there was before,” Dana Loomis, the deputy head of IARC’s Monograph classification department told a news conference.
At the same time, however, IARC presented other scientific evidence which suggests that drinking anything very hot around 65 degrees Celsius or above - including water, coffee, tea and other beverages, probably does cause cancer of the oesophagus.
Lyon-based IARC, which last year prompted headlines worldwide by saying processed meat can cause cancer, reached its conclusions after reviewing more than 1,000 scientific studies in humans and animals. There was inadequate evidence for coffee to be classified as either carcinogenic or not carcinogenic.
IARC had previously put coffee as a “possible carcinogen” in its 2B category alongside chloroform, lead and many other substances. The U.S. National Coffee Association welcomed the change in IARC’s classification as “great news for coffee drinkers”.
The Institute for Scientific Information on Coffee, whose members are six of the major European coffee companies - illycaffè, Jacobs Douwe Egberts, Lavazza, Nestlé (NESN.S), Paulig, and Tchibo - said IARC had found “no negative relationship between coffee consumption and cancer”. In its evaluation of very hot drinks, IARC said animal studies suggest carcinogenic effects probably occur with drinking temperatures of 65 Celsius or above. Some experiments with rats and mice found “very hot” liquids, including water, could promote the development of tumours, it said.
The agency said studies of hot drinks such as maté, an infusion consumed mainly in South America, tea and other drinks in several countries including China, Iran, Japan and Turkey, found the risk of oesophageal cancer “may increase with the temperature of the drink” above 65 Celsius. “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.