Coffee and IARC: What are the facts?
The International Agency for Research on Cancer (IARC) recently revised its classification of coffee to Group 3: ‘Not classifiable as to carcinogenicity’. We’ve explained below what this means in the context of everyday life, and provided answers to some questions healthcare professionals may get from their patients. For additional information, please refer to our cancer topic section of the website and our news alert responding to the latest IARC decision on coffee.
What is IARC and what does it do?
The International Agency for Research on Cancer (IARC) is the specialised cancer agency of the World Health Organisation (WHO). IARC classifies chemicals, common foods and beverages into 5 categories based on the strength of evidence that they may cause cancer.
These groups are:
- Group 1: Carcinogenic to humans
- Group 2A: Probably carcinogenic to humans
- Group 2B: Possibly carcinogenic to humans
- Group 3: Not classifiable as to carcinogenicity
- Group 4: Probably not carcinogenic
It is important to note that IARC’s classification system does not reflect a judgement or measure of the likely risk to public health in everyday life. To date, IARC has only classified one substance in Group 4.
Why has IARC reclassified coffee?
In June 2016, IARC downgraded their original 1991 classification of coffee from Group 2B (‘possibly carcinogenic to humans’) to Group 3: ‘Not classifiable as to carcinogenicity’. This means that after reviewing over 1,000 studies, IARC has judged that the extensive scientific literature does not show evidence of an association between coffee consumption and cancer.
Not only did IARC find no clear association between coffee intake and cancer at any body site, it also found that in some cases, there is evidence that coffee drinking may actually help reduce occurrence of certain cancers; specifically, cancers of the liver and uterine endometrium.
Does IARC’s conclusion mean that drinking coffee could affect someone’s risk of developing cancer?
IARC’s new classification of coffee into Group 3 means that extensive scientific research does not show an association between coffee consumption and cancer. In addition, IARC also found evidence that coffee drinking may actually help reduce occurrence of certain cancers: citing reduced risks for cancers of the liver and uterine endometrium.
For more information on the scientific evidence relating to coffee and cancer, including how coffee could help reduce the risk of certain cancers, please read our cancer topic overview.
What is IARC’s conclusion on cancer and very hot beverages?
In June 2016, IARC classified drinks consumed at very high temperatures over 65°C in Group 2A: “probably carcinogenic to the human oesophagus”. This new classification defined ‘very hot beverages’ as drinks consumed at temperatures significantly hotter than those at which most people can comfortably drink coffee without scalding their mouth and tongue.
Does drinking very hot coffee cause cancer?
IARC’s assessment looked at all very hot beverages, not just coffee. When IARC assessed evidence for a link between oesophageal cancer and coffee specifically, it found insufficient evidence of an association. Coffee is one of the most widely consumed hot beverages worldwide and it is typically drunk at temperatures well below IARC’s definition of ‘very hot’.
IARC’s view is that it is the temperature at which a drink is consumed, not the type of drink itself, that could potentially increase the risk of developing oesophageal cancer.
It’s also important to stress that IARC is just evaluating the science, not assessing consumption habits in everyday life.
What temperature do people normally drink their coffee at?
Coffee is typically drunk at temperatures lower than 60°C, which is well below IARC’s definition of a ‘very hot beverage’.
IARC’s assessment on very hot beverages, which reviewed beverages consumed at ‘scalding’ temperatures above 65°C, doesn’t reflect the way people normally drink their coffee.
Liquid temperatures higher than 65°C are above the normal human pain threshold, and a consumer should not be able to comfortably drink their coffee if it is hotter than 65°C.
This information is intended for Healthcare professional audiences.
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