Social media was alive with ravenous carnivores (and smug vegetarians) after the WHO released a statement on the carcinogenic effects of red and processed meat. This prompted many news outlets to run headlines comparing red meat to cigarettes. Some serious bacon-rage ensued.
Now, before you lament your inevitable death-by-cheeseburgers, it's important to understand what the implications of the WHO's statement actually are.
Who are these 'meat-haters,' anyway?
The International Agency for Research on Cancer (known as the IARC) is an agency of the World Health Organization (WHO), tasked with evaluating all sorts of things (from smoking to microwave ovens) and determining if they cause cancer or not. They do this by evaluating the body of evidence that already exists. They then make a determination -- yes, no, or maybe. Being classified as Group 1 means that something is an established carcinogen, like asbestos or cigarette smoking. Groups 2A and 2B are probably and possibly carcinogenic, respectively. Group 3 means there's not enough data to be classified.
What did the IARC actually find?
According to the full report, published Oct. 26, 2015 in the Lancet Oncology, a working group made up of 22 scientists from all over the world convened to evaluate the carcinogenicity of red meat and processed meat. They reviewed 800 diverse studies, and based on their findings and the strength of their research methodologies, drew conclusions.
There were approximately 30 studies examining the association between red meat and colorectal cancer, and approximately 30 more pertaining to processed meat and colorectal cancer. About half of these showed a positive association.
There were also studies looking at the associations between red and processed meat and many other cancers, and positive associations were seen between consumption of red meat and cancers of the pancreas and the prostate, and between consumption of processed meat and stomach cancers.
On the basis of these findings, the IARC concluded that consumption of processed meat was "carcinogenic to humans" (Group 1) on the basis of sufficient evidence for colorectal cancer, and a positive association with the consumption of processed meat and stomach cancer.
They classified the consumption of red meat as "probably carcinogenic to humans" (Group 2A), based on the positive association between consumption of red meat and colorectal, pancreatic and prostate cancer.
Is bacon as bad as arsenic?
The first important point to stress is that the IARC classification is based on the strength of the evidence supporting a relationship, not the strength of the relationship. In other words, it answers the question "Is there a relationship between red and processed meat and cancer?" but does NOT answer the question "How strong is the relationship between red and processed meat and cancer?" or, more importantly, "How much more likely am I to get cancer if I eat red or processed meat?" and "If I stop eating red or processed meat, how much less likely am I to get cancer?"
So, when you read that processed meat has "Grade 1" status, just like cigarette smoking, arsenic, or asbestos, it just means that the WHO is as confident in the relationship between processed meat and cancer as it is the relationship between cigarette smoking and cancer. NOT that processed meat is as likely to cause cancer as cigarette smoking is. And want to know what else is classified as Grade 1? Alcohol. Epstein-Barr virus (the virus that causes mono). And a bunch of life-saving medications.
So... Can I have my bacon and eat it too?
I'm not trying to downplay the IARC's findings. They are meaningful. An association was found and it wasn't thought to be random. This means more research into this is warranted to answer those other questions we all now have, like how risky consuming red and processed meat is or how beneficial it would be to stop eating them. But the WHO's statement didn't give us much by way of guidance. They told us to eat these foods in moderation, and balance this potential risk with all the benefits of eating meat.
So, like alcohol, consume in moderation and exercise caution. And my two cents, as a gastroenterologist -- if you really want to prevent colorectal cancer? Get a screening colonoscopy!
This piece was originally published on http://bellyblog.ca.
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