The International Agency for Research on Cancer (IARC), the cancer agency of WHO, evaluated the evidence for cancer risk from the consumption of red meat and processed meat – finding that the consumption of red meat is ‘probably carcinogenic to humans’ while processed meats were found to be ‘carcinogenic to humans.’
A working Group of 22 experts from 10 countries convened by IARC said processed meat was classified as carcinogenic to humans, “based on sufficient evidence in humans that the consumption of processed meat causes colorectal cancer.”
The experts concluded that each 50 gram portion of processed meat – which includes the likes of cured meats, sausages, bacon and other prepared meat snacks – eaten daily increases the risk of colorectal cancer by 18%.
“For an individual, the risk of developing colorectal cancer because of their consumption of processed meat remains small, but this risk increases with the amount of meat consumed,” said Dr Kurt Straif, head of the IARC Monographs Programme. “In view of the large number of people who consume processed meat, the global impact on cancer incidence is of public health importance.”
- Processed meats are meat that has been modified to increase its shelf-life or alter its taste - such as by smoking, curing or adding salt or preservatives
- These meats have been classified as definite causes of cancer
- IARC group 1 classification simply means a link has been established. All substances on the list do not carry the same cancer risk though
- Evidence suggests that 50 grams of processed meat is liked to an 18% increased risk of colorectal cancer
As a result, processed meats have been placed in Group 1 of its list of carcinogens that definitely do cause cancer – alongside substances including cigarettes, alcohol, asbestos, plutonium and arsenic.
The Group 1 classification, however, is not an indication of how much cancer each substance causes – just that it does cause cancer – and therefore does not mean eating processed meats like sausages are carry the same cancer risk as smoking.
"IARC does ‘hazard identification’, not ‘risk assessment’. That sounds quite technical, but what it means is that IARC isn’t in the business of telling us how potent something is in causing cancer – only whether it does so or not," noted Professor David Phillips from King's College London, in a Cancer Research UK post on the WHO findings.
Indeed, Dr Ian Johnson at the UK's Institute of Food Research (IFR) said it is important to emphasise that the size of the effect is relatively small: "It is certainly very inappropriate to suggest that any adverse effect of bacon and sausages on the risk of bowel cancer is comparable to the dangers of tobacco smoke, which is loaded with known chemical carcinogens and increases the risk of lung cancer in cigarette smokers by around 20 fold," he said.
Red meat risk?
While much focus has been put on the classification of processed meats as carcinogenic, the WHO report also classified red meats as ‘probably carcinogenic’ – however, it noted that the evidence for this classification is much more limited.
“These findings further support current public health recommendations to limit intake of meat,” said Dr Christopher Wild, director of IARC.
“At the same time, red meat has nutritional value. Therefore, these results are important in enabling governments and international regulatory agencies to conduct risk assessments, in order to balance the risks and benefits of eating red meat and processed meat and to provide the best possible dietary recommendations.”
A statement from the North American Meat Institute (NAMI) said the IARC classification defies common sense and numerous studies that have found no correlation between meat and cancer - adding that cancer is a complex disease "not caused by single foods and that a balanced diet and healthy lifestyle choices are essential to good health."
“Followers of the Mediterranean diet eat double the recommended amount of processed meats. People in countries where the Mediterranean diet is followed, like Spain, Italy and France, have some of the longest lifespans in the world and excellent health,” commented Betsy Booren, Ph.D., NAMI Vice President of Scientific Affairs - who added that risks and benefits must be considered together.
Source: The Lancet Oncology
Published online, Open Access, doi: 10.1016/S1470-2045(15)00444-1
"Carcinogenicity of consumption of red and processed meat"
Authors: Véronique Bouvard, et al