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WHO Declares Bacon and Red Meat (Probable) Carcinogens

Dean Pomerleau

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It appears from this article that the World Health Organization is on the verge of declaring bacon, sausage and processed meat carcinogens, and red meat generally as a probably carcinogen, perhaps as early as tomorrow. To quote from the article:


In doing so, the WHO would likely be classifying these processed food items in the same category as cigarettes and asbestos. 
Given the meat industry lobbying power in the US, this will likely be a pretty big deal, and cause quite a bit of controversy. It will be interesting to see how it plays out. Perhaps they'll sue the WHO for defamation like they did Oprah.  :)xyz
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Yup, sure enough, NPR calls it a "Bad Day for Bacon". I call it a good day for pigs (and cows & sheep)!


The WHO released a review that lists processed meat in its "group 1" list of carcinogens, which also includes tobacco and asbestos for which there is "sufficient evidence" of cancer links. In addition, the WHO says red meats including beef, pork, veal and lamb are "probably carcinogenic" to people.


To quote from the text of the report [1] published today in Lancet:


The Working Group assessed more than 800 epidemiological studies that investigated the association of cancer with consumption of red meat or processed meat in many countries, from several continents, with diverse ethnicities and diets. For the evaluation, the greatest weight was given to prospective cohort studies done in the general population. High quality population-based case-control studies provided additional evidence. For both designs, the studies judged to be most informative were those that considered red meat and processed meat separately, had quantitative dietary data obtained from validated questionnaires, a large sample size, and controlled for the major potential confounders for the cancer sites concerned.




A meta-analysis of colorectal cancer in ten cohort studies reported a statistically significant dose–response relationship, with a 17% increased risk (95% CI 1·05–1·31) per 100 g day of red meat and an 18% increase (95% CI 1·10–1·28) per 50 g per day of processed meat [2]. 




On the basis of the large amount of data and the consistent associations of colorectal cancer with consumption of processed meat across studies in different populations, which make chance, bias, and confounding unlikely as explanations, a majority of the Working Group concluded that there is sufficient evidence in human beings for the carcinogenicity of the consumption of processed meat.


Chance, bias, and confounding could not be ruled out with the same degree of confidence for the data on red meat consumption, since no clear association was seen in several of the high quality studies and residual confounding from other diet and lifestyle risk is difficult to exclude. The Working Group concluded that there is limited evidence in human beings for the carcinogenicity of the consumption of red meat.




Overall, the Working Group classified consumption of processed meat as “carcinogenic to humans” (Group 1) on the basis of sufficient evidence for colorectal cancer. Additionally, a positive association with the consumption of processed meat was found for stomach cancer. The Working Group classified consumption of red meat as “probably carcinogenic to humans” (Group 2A). In making this evaluation, the Working Group took into consideration all the relevant data, including the substantial epidemiological data showing a positive association between consumption of red meat and colorectal cancer and the strong mechanistic evidence. Consumption of red meat was also positively associated with pancreatic and with prostate cancer.


Not surprisingly, the meat industry isn't taking this move lightly. The North American Meat Institute was quick to hit back with a statement, saying of the WHO report and its content:

  • It is "a dramatic and alarmist overreach",
  • It "def(ies) both common sense and dozens of studies showing no correlation between meat and cancer",
  • lots of things cause cancer,
  • "cancer is complex and a balanced diet is key to staying healthy".

I encourage you to read the meat industry statement for yourself to see if its claims are credible, or simply a smoke screen similar to that employed by the tobacco industry to avoid and obfuscate the evidence of harm from their product...





[1] The Lancet Oncology, Published Online: 26 October 2015


Carcinogenicity of consumption of red and processed meat

Véronique Bouvard, Dana Loomis, Kathryn Z Guyton, Yann Grosse, Fatiha El Ghissassi, Lamia Benbrahim-Tallaa, Neela Guha, Heidi Mattock, Kurt Straif on behalf of the International Agency for Research on Cancer Monograph Working Group





[2] Chan DS, Lau R, Aune D, et al. Red and processed meat and colorectal cancer incidence: meta-analysis of prospective studies. PLoS One 2011; 6: e20456.

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Amen! More reasons to stop eating animals.


I (obviously) agree. But I also think that it's worth keeping the increased risk of colon cancer from eating processed and red meat in perspective. According to the studies reviewed by the WHO for this report, eating 50g of processed meat per day (equivalent to two strips of bacon every day), increases one's lifetime risk of colon cancer by 18%.


From this handy table on lifetime risk of various cancers, a person's risk of developing colorectal cancer is about one in 21. Put another way, about 5 in 100 people will develop colorectal cancer in their lifetime, and two in 100 will die from it. If everyone were to eat two strips of bacon every day for life, it would increase the lifetime incidence of colorectal cancer from five to six people in 100. Compare this to picking up the habit of smoking, which raises lifetime risk of lung cancer from ~1.4 to 17 people in 100, nearly all of whom eventually die from the disease [1].





[1] Can J Public Health. 1994 Nov-Dec;85(6):385-8.

Lifetime probability of developing lung cancer, by smoking status, Canada.


Villeneuve PJ(1), Mao Y.


Life table methodology was used to estimate the probability of developing lung

cancer by smoking status. Lifetime risks of developing lung cancer were estimated

for six hypothetical cohorts (males, females, male current smokers, male never

smokers, female current smokers, and female never smokers). Estimates of smoking

mortality and incidence rates were calculated based on Canadian rates observed

over the period 1987 to 1989. It was found that 172/1,000 of male current smokers

will eventually develop lung cancer; the similar probability among female current

smokers was 116/1,000. For those who never smoked on a regular basis the lifetime

risk was substantially reduced. Only 13/1,000 males and 14/1,000 females in this

category will develop lung cancer. When smoking status is not adjusted for, the

lifetime risk of developing lung cancer is approximately 96/1,000 and 43/1,000

for males and females respectively.


PMID: 7895211

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I want just to mention  that famous lists containing processed meat in its "group 1" list of carcinogens  contains also alcohol since many years. There were no just media attention, at least in my countries about that. And how about the usual combo, sausage with alcohol, quite tradiional in my country (France). The funny part is that IARC is a french-based agency.

From wikipedia:"

Alcoholic beverages are classified by the International Agency for Research on Cancer (IARC) as a Group 1 carcinogen (carcinogenic to humans). IARC classifies alcoholic beverage consumption as a cause of female breast, colorectum, larynx, liver, esophagus, oral cavity, and pharynx cancers; and as a probable cause of pancreatic cancer"

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