Coffee consumers across the globe can continue to sip their favourite beverage without fear. The World Health Organisation says there’s not enough evidence to rule that coffee causes cancer.
By
Yasmin Noone

16 Jun 2016 - 8:38 AM  UPDATED 19 Jun 2016 - 10:25 AM

Coffee-lovers all around Australia can slowly inhale the fresh aromas of a rich, whole-bodied espresso and lick their disposable skim cappuccino-filled spoons within a joyful ease this morning, as the World Health Organization (WHO) concludes that there's no evidence to prove that coffee causes cancer.

The International Agency for Research on Cancer (IARC), the cancer agency of the WHO, has placed coffee into a group three-cancer classification and determined that there is “no conclusive evidence that coffee has a carcinogenic effect”.

Ironically, it was a cup of coffee that kept this Australian journalist awake long enough to receive the findings live via a virtual media conference from the European centre late last night.

The IARC, which made headlines for it’s ‘bacon is bad for you’ ruling last year, also found that drinking coffee was associated with a reduced risk of endometrialand liver cancer.

good cup

“People who drink coffee have lower risks of those types of cancer than those who do not,” says Dr Dana Loomis, Deputy Head, IARC Monographs Programme.

Now, if you had stopped drinking coffee because you’d heard it could cause cancer, it’s not a lack of coffee that’s sending you stir crazy. The same agency rated coffee as “possibly carcinogenic” 25 years ago.

Although the new ruling may mark a scientific backtrack of sorts, WHO’s new coffee categorisation is based on a review of all the literature and more recent evidence.

“This was not the first time we have downgraded a classification but it happens seldom.”

The IRAC did also deliver some bad news. Hot brew drinkers should heed the WHO’s warning that very hot drinks, consumed over 65 degrees Celsius “probably causes cancer” of the oesophagus.

“People who are concerned should wait a few minutes to drink their coffee or tea.”

It is traditional for some cultures to drink beverages at very hot temperatures – for example the South American brew, mate, is typically consumed at 70 degrees. But Dr Loomis explains that most people in the west usually drink their beverages at around 60 degrees.

So if we don’t usually consume beverages at cancer-causing temperatures, how will we know if we’ve hit the deadly 65 degrees mark? “Well, if you spill 60 degree water on you, it hurts,” he says. “Some surveys show that people who drink tea burnt their tongues if it was tea over 70 degrees.”

There is a downside to this beverage story: the IARC still seems to be sitting on the coffee-coloured fence in clearly classifying coffee’s carcinogenic risk.

“The data did not permit a conclusion that it is safe or dangerous,” says Dr Loomis.  “A group three classification does not show that coffee is certainly safe but it shows that there is no clear indication of risk associated with coffee.”

That basically means that scientists don’t actually know if coffee causes cancer because the evidence available doesn’t point to a yes or no. Coffee may cause cancer but there’s just not enough available research to determine the fact either way.

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Although it may seem a bit rich that 20 of the world’s experts on cancer can’t figure it out after examining 1000 studies on the topic, Dr Loomis says it’s actually fair enough.

He reports that a lot of the studies are old and their results could have skewed the literature review’s overall findings. As time goes on and the number of recent studies increase (based on modern scientific methods), Dr Loomis expects to see a more definitive result. However, he reports, there are no current plans for the IARC to conduct another mass review soon.

"...the take-home message is: Enjoy your coffee with peace of mind but don’t drink it very hot!"

Professor Bruce Armstrong, an adjunct professor in the School of Population Health at the University of Western Sydney and emeritus professor at the University of Sydney, says that while "this evidence was apparently not considered strong enough to suggest that coffee drinking lacks carcinogenicity (a conclusion that IARC sometimes reaches).... from a practical public health perspective, however, it would be reasonable to conclude from the IARC review that coffee drinking is unlikely to increase a coffee drinker’s risk of cancer."

"So the take-home message is: Enjoy your coffee with peace of mind but don’t drink it very hot!" 

Dr Loomis stresses that the experts' ruling applies only to coffee, not all caffeine products, as there are 100 different chemicals that differentiate coffee from other forms of caffeine.

He explains that the group could also not rule on quantity, as the evidence does not demonstrate that more coffee influences cancer risk on the whole. 

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