This two page summarizes that based off of the evidence available the IARC concluded that processed meats cause cancer and they think red meat might but they can't be sure.
A more detailed report was published in the Lancet, which is free to view but requires you to register:
After reading that review, here are some notes:
1. The claim of carcinogen is mostly for colorectal cancer, although some studies reported red meat links to pancreas/prostate cancer while processed meat was linked to stomach cancer.
2. Red meat consumption and colorectal cancer association was found in 7 of 14 studies cohort studies and in 7 of 15 case control studies. That's 14 of 29 that found a link and 15 that didn't.
3. Processed meat and colorectal cancer association was found in 12 of 18 cohort studies and 6 of 9 case control studies. That's exactly 2/3 of the cases.
4. The big finding via meta analysis was that every extra 100g of red meat per day increased the colorectal cancer risk by 17% and every 50g of extra processed meat increased the risk by 18%.
As always, keep in mind the severe limitations of nutrition research, led by the foundational flaw that most nutrition research is limited by nature because of how the data is primarily collected (i.e. tell me how much processed meat you eat on average a week this year, last year, etc.) and then matched to health outcomes (colorectal cancer occurrence).
Nutrition doesn't take place in a vacuum. Other things impact nutrition. How do we know that the people who choose processed and/or red meat don't eat an extra 20 grams of sugar a day, have a history with antibiotics, sleep a half hour less or have more stressful jobs? No matter how much researchers try to control for other variables it's literally impossible to simplify nutrition at this point in time.
Web MD covered it very nicely:
Meat & Cancer: What's the risk?A great little article I suggest reading entirely but here is one of the big takeaways:
Each daily 50-gram portion of processed meats - about the size of an average hot dog - increases the risk of colorectal cancers by 18%, the report says. Each daily, 100-gram portion of red meat - about one-quarter of a pound - raises colorectal cancer risk by 17%.
In absolute terms, the increased risk is pretty small. For example, the risk that a man will get colorectal cancer during the course of his lifetime is about 4.8%, on average - or said differently, about 1 in 21 men will develop it in his lifetime. A 17% increase in that risk bumps it up to 5.6%, or changes that risk to about 1 in 18 men.
By comparison, a 2005 study determined that smoking a single daily cigarette could increase a person's risk of lung cancer by about 200% to 400%.
So, if this is indeed correct and true, which we're still not quite sure, then a man adding a hot dog a day to his diet raises his risk of developing colon cancer some time in his life from 4.8 to 5.6%. Why are we comparing that to cigarettes and asbestos, again?
Again, possibly most importantly, we still don't have a clear mechanism. Meaning, we don't know how it happens or why it happens. I wonder, with a difference this small and no mechanism, can we be sure it's even really happening? Maybe it is but it reminds me a lot of the saturated fat, cholesterol and salt journey we've already been down.
Question: Why do we keep doing this to people? We don't really know it for a fact, we just suspect. And we really want to find the ONE thing that's bad so we can say, "Ah-ha! This is it! Processed meat! That is why we are getting sicker and fatter! Just cut that out and things will be fine. What? Oh no, it's not the bun, french fries and 32 ounce soda, it's the meat!"
There are a hundred reasons why people get sick and it's not probably not processed meat, certainly not all by itself. We like to search for simple answers to our complex questions because it's easier to say eliminate bacon instead of minding all the other things that contribute to health because tackling those is too big of an issue.
Here's an interesting Q & A on the report from the WHO.
Once again, worth reading, but here's 2 important takeaways:
- They are listing processed meats as "evidence supports causal link to cancer" which falls into the same category as tobacco and asbestos but that doesn't mean it's as dangerous.
- There is still very much that is unknown, particularly when you start looking for specifics and nuances into this issue. There is more unknown that known at the moment.
To me it's a dangerous practice to put the blame on red meat and processed meat. We've already been down this road with fat, salt and cholesterol. Hot dogs might not be the "healthiest" thing on the planet but neither is the bun they come in or the chili and cheese often smothered on them or the soda on the side or the concept that they might be simply part of a calorie overload (which might be the biggest issue of all).
Let's keep looking at the whole picture and focusing our efforts on the basic health improvement pursuits, not wasting time trying to figure out how to blame something specific for a general problem.
Thanks for reading, have a great day!
P.S. Could it be possible that the people eating all the processed and red meat have the worst diets and lifestyle? If so, what if eating read meat actually prevents them from having even worse health outcomes...?
