WHO tells us about red meat and processed meat cancer risk?

See what I did there?

As you know, the UN WHO International Agency for Research on Cancer has listed Red Meat as Group 2A (probably carcinogenic to humans) and processed meat at Group 1 (causes cancer).

And everyone is upset. The most common reaction to these listings is to criticize WHO. The least common reaction to these listings is to learn what the listings are, what they mean, what they mean to you, to the meat industry, to cancer research, and all that. Here, I will try to provide some perspective on some of this.

WHO is probably more likely to list something as cancer causing

It is probably true that the WHO IARC is somewhat biased, in that they are more likely to attribute possible carcinogenic effects to things than other similar groups. There are many substances and behaviors listed by WHO as possibly or probably cancer causing that are not similarly identified by, for example, the US EPA. This does not mean that WHO IARC is more likely to be wrong. It just means that your reaction to a possible agent being listed by WHO should be to understand this bias, but not to assume you know what the bias means. If every single cancer-watching agencies was biased in one direction, we'd have a problem. If all cancer-watching agencies always drew the same exact conclusions form the disparate research, we'd have a conspiracy. If the range of cancer-watching agencies produces a reasonable range of decisions, we'd have real life.

Here is something you should keep in mind when comparing across agencies. Many US federal agencies are led and staffed by industry experts. Where do you get industry experts? From the industries these agencies regulate. Where did the industries get them? They got them from PhD schools, where they quite possibly paid for their higher education with grants from the industry and worked in labs paid for in part by those industries, while working on grants from the industry. This is likely more a thing in the US than in other countries that contribute expertise and do research. It is also true that US regulatory agencies are notably biased in the opposite direction of WHO.

US regulatory agencies will be staffed by well meaning well trained people who know a lot about how the industry works. That is a good thing. US regulatory agencies will be staffed by people who owe their careers to the industry, and are likely to have warm fuzzy feelings about the industry. That is likely to lead to some bias.

On the other hand, in other parts of the world, wooish thinking seems to permeate science and governmental agencies more easily. If you look at the research and regulations, related to EMF risks (like power lines and cell phones and such) you'll see a gradient where some areas of Europe have both evidence (from research) suggesting EMF-health risks and regulations related to this, and other areas of Europe where the evidence shows now risk, to the US where we by and large don't regulate EMF using these risks as factors. A sensible view of the research tells us that EMF does not have the alleged health risks.

The reason this is important is that WHO is an international body, so we are going to see a range of industry-fuzzy vs. woo-fuzzy fringes surrounding a hopefully larger and sensible scientifically oriented core. This is also important because of this: if every regulatory or research agency or institution in the world really were funded by the industries they study, and no other research was done by anybody, problems will arise. So go ahead and be annoyed at WHO, but also appreciate this relationship.

It is not about how bad the cancer risk is

As a substance or behavior moves from Group 3, through Group 2B and 2A, to Group 1, this does not mean that it is thought to be increasingly cancer-causing. What it means is that the certainty that the substance or behavior cases cancer, no matter how small the effect, has increased. A given agent may increase the risk of a certain kind of cancer by 50%, which sounds bad, but the original probability of cancer being caused by that agent may be tiny. So, in effect, a tiny risk has been increased to a tiny risk. According to WHO, "The classifications reflect the strength of the scientific evidence as to whether an agent causes cancer in humans but do not reflect how strong the effect is on the risk of developing cancer."

This is not about your bacon

I find it amusing that the Internet Reaction to these listings is so widespread and negative, even angry, and at the same time so poorly informed. This is amusing because we are just coming off a way over the top Bacon Worship phase.

I stopped eating bacon about four months ago. Do you want to know why? Because of all the pictures of bacon, excessive bacon, things made out of bacon, bacon being fetishized and revered like it was a god or something, on Facebook and elsewhere. I got tired of bacon. I was reminded of a friend's comment. He was raised in a Kosher household. He told me, "I don't have any food taboos, I don't keep kosher. But if I walk into a house where someone is cooking ham, I want to throw up."

(OK, I did have a BLT the other day. But it was hard.)

The point is, do think about the nature and cause of your reaction, if you are having a hissy fit about WHO and meats. Are you objecting to the WHO IARC criteria, which you've carefully studied and understand, or are you simply being sensitive about your stupid bacon fetish? Think about it.

Some food research is probably inherently wrong

I just want to throw this in. If you feed human food, especially cooked food, especially food not made of raw grains, to rats and mice, they might get sick, while a human being fed the same things won't. Why? Because humans invented cooking possibly as long as two million years ago, and have adapted to cooked foods which seem to cause nasty problems for some lab animals. And humans and their ancestors have always eaten at least some meat. And we are not rodent granivores. So, I don't know how much animal evidence is being used to change the groups for meat and processed meat, but I personally prefer to disregard rodent data on human diet. It seems to be almost always misleading. Just sayin'

IARC Groups

Just so you know, here are the IARD Groups

Group 1: The agent is carcinogenic to humans. This category is used when there is sufficient evidence of carcinogenicity in humans. In other words, there is convincing evidence that the agent causes cancer. The evaluation is usually based on epidemiological studies showing development of cancer in exposed humans. Agents can also be classified in Group 1 based on sufficient evidence of carcinogenicity in experimental animals supported by strong evidence in exposed humans that the agent has effects that are important for cancer development.

Group 2 This category includes agents with a range of evidence of carcinogenicity in humans and in experimental animals. At one extreme are agents with positive but not conclusive evidence in humans. At the other extreme are agents for which evidence in humans is not available but for which there is sufficient evidence of carcinogenicity in experimental animals. There are two subcategories, indicating different levels of evidence.

Group 2A: The agent is probably carcinogenic to humans. This category is used when there is limited evidence of carcinogenicity in humans and sufficient evidence of carcinogenicity in experimental animals. Limited evidence means that a positive association has been observed between exposure to the agent and cancer but that other explanations for the observations (technically termed chance, bias, or confounding) could not be ruled out.

Group 2B: The agent is possibly carcinogenic to humans. This category is used when there is limited evidence of carcinogenicity in humans and less than sufficient evidence of carcinogenicity in experimental animals. It may also be used when the evidence of carcinogenicity in humans does not permit a conclusion to be drawn (referred to as “inadequate” evidence) but there is sufficient evidence of carcinogenicity in experimental animals.

Group 3: The agent is not classifiable as to its carcinogenicity to humans. This category is used most commonly when the evidence of carcinogenicity is inadequate in humans and inadequate or limited in experimental animals. Limited evidence in experimental animals means that the available information suggests a carcinogenic effect but is not conclusive.

Group 4: The agent is probably not carcinogenic to humans. This category is used when there is evidence suggesting lack of carcinogenicity in humans and in experimental animals.

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Does this mean I won't need a Hazmat suit to make a BLT?

I stopped eating bacon about four months ago.

For people bacon is a choice. For the pig it's a commitment.

The most common reaction to these listings is to criticize WHO. The least common reaction to these listings is to learn what the listings are, what they mean, what they mean to you, to the meat industry, to cancer research, and all that.

Indeed, but those distinctions can be made about almost any bit of science that ends up being widely discussed in the press. I have already received about a dozen emails from friends mocking this story, the scientists who did it, and the "foolishness" of basing decisions on statistics and data. Most is in jest, but three were quite serious in their complaints about "lazy researchers writing crap just for the money".

As with all things, the dose makes the poison. Eating small amounts of meat occasionally is, for most people, a reasonable thing that doesn't involve a great deal of risk. (The exceptions are people who, for specific medical or religious reasons, need to avoid meat in their diet.) A diet consisting primarily of red meat and processed meat is almost certainly not a good idea, and not just because of the increased cancer risk.

By Eric Lund (not verified) on 27 Oct 2015 #permalink

Indeed: The most common reaction to these climate science findings is to criticize climate science professionals and organizations such as the IPCC. The least common reaction to these findings is to learn what the findings are, what they mean, what they mean to you, to the fossil fuel industry, to protecting and preserving our future, and all that.

Not much difference. And as Dean points out, lots of deniers quite serious in their complaints about “lazy climate researchers writing crap just for the money”.

By Brainstorms (not verified) on 27 Oct 2015 #permalink

I heard a TV talking head yesterday (a doctor - if that matters) say that the magnitude of the risk was relatively small.

He was explaining what it meant that processed meat was in the same category as smoking.

If you eat a hot dog everyday for your entire life your risk of getting bowel cancer would rise from 5% to 6%.

The magnitude of risk from smoking is much much higher than the magnitude of risk from eating bacon or hot dogs - but the WHO puts them in the same category.

So like everything else - one has to evaluate the science in context.

Certainly I will still be eating bacon occasionally and having a hot dog occasionally. But as Eric says - moderation in everything.

It would be enlightening to do a study to find out if these observations are caused not by eating red meat/meat products, but instead caused (primarily?) by their consumption displacing the eating of fruits and vegetables -- the consumption of which are already known to reduce the incidence of colo-rectal cancer.

From my observations, most who focus on eating a meat-heavy diet also eschew eating "green things" as in, "That's not food, that's what food eats." Can't be healthy!

But such a study would have to pit those eating a fruit-and-vegetable-heavy diet against those *not* eating sufficient fruits and vegetables, yet also not eating a diet heavy in red meat/meat products -- to discern whether or not the cancers are actually a consequence of not eating lots of fruits and vegetables.

Which, of course, isn't possible...

So, until that's resolved, I'll continue to leaven my judicious red (and non-red) meat eating with plenty of fruits and vegetables. (I already forgo fast food in favor of slow food, which would be the basis of more enlightening studies.)

By Brainstorms (not verified) on 27 Oct 2015 #permalink

Are there differences between organic and non-organic meats?

Are there differences between meats that are processed traditionally and meats that are processed industrially?

By cosmicomics (not verified) on 27 Oct 2015 #permalink

I think the paleo diet includes meat, fish, fruit and vegetables.

I wonder what difference cooking the meat makes.

I know cooked meat is safer from bacteria and so on - but cooking also introduces carcinogens (I believe).

So that is three variables that could be checked out.

Organic vs non-organic.
Traditionally processed vs. commercial processing.
Raw vs. cooked.

That would be an interesting study.

But such a study would have to pit those eating a fruit-and-vegetable-heavy diet against those *not* eating sufficient fruits and vegetables, yet also not eating a diet heavy in red meat/meat products — to discern whether or not the cancers are actually a consequence of not eating lots of fruits and vegetables.
Which, of course, isn’t possible….

You couldn't do a randomized study, you're correct. A retrospective study could be done, but sussing out dietary habits like this over a lifetime would be (I suspect) more difficult than usual.

Are there differences between organic and non-organic meats?

Presumably, yes: The "organic" ones are not pumped full of growth hormones and antibiotics throughout their lives.

Are there differences between meats that are processed traditionally and meats that are processed industrially?

Again, presumably yes: Traditional processing doesn't involve chemical preservatives, additives, fillers, etc.

My philosophy: If it won't rot outside the fridge within a few days, don't eat it!

By Brainstorms (not verified) on 27 Oct 2015 #permalink

The "paleo diet" fad has been debunked.

Also, studies (Rachel Carmody, Richard Wrangham; http://www.scientificamerican.com/article/cooking-up-bigger-brains/) have shown that cooking makes a big difference for humans: Our large brains' need for energy requires that we cook our food in order to extract enough calories. I.e., if you ate uncooked food only, you would need to eat more than 24 hours a day to extract enough calories.

Carcinogens or no, you must cook to live...

By Brainstorms (not verified) on 27 Oct 2015 #permalink

You couldn’t do a randomized study, you’re correct. A retrospective study could be done, but sussing out dietary habits like this over a lifetime would be (I suspect) more difficult than usual.

I think the problem is more fundamental (although you make an excellent point): If your control group doesn't eat primarily fruits and vegetables, and doesn't eat meat, what then *do* they eat? (Perhaps a Japanese-like diet of starch and fish?)

By Brainstorms (not verified) on 27 Oct 2015 #permalink

Brainstorms@13:
Even more than your points: roughly, even if you have a large group of people who have been diagnosed with (say) colorectal cancer, obtaining the information on their long-term dietary habits would be very difficult (I'm guessing more difficult than usual) because the evidence would be entirely memory based, with no way to validate the information. Lots of bias comes in immediately.

"Traditional processing" does include such things as salt, brine, mustard and other spices, and smoking. To characterise these as not chemical is a major error. Just as mistaken is to denigrate "fillers and additives" as industrial. They (especially fillers) are usually considered as fibre or ash, a necessary component of a healthy diet.

You are wise in not eating something that appears not to rot when not refrigerated. These items can still be contaminated by a low level of bacterial growth regardless of preservatives and may also be partially oxidized (rancid). Still our ancestors and other animals as well as many living humans did and do quite well on food contaminated past the acceptable levels of wholesomeness dictated by the FDA. Animal digestive systems are amazing in what they can assimilate and reject for good reason.

Jockaira, yes, you are correct, using technical definitions. I was speaking more colloquially, using the connotation that "chemical" implies industrial & non-natural, and that "fillers and additives” are taken to mean similar non-natural industrial additives, chosen for things such as profit, mouth-feel, and shelf-life, rather than a traditional filler.

It's interesting that the traditional Japanese diet is heavy on pickled food and (briny) soy sauces -- and they have a notably high incidence of stomach cancer. Connection?

I'm a big proponent of teaching people about rancidity of oils and processed foods containing food oils. There is a major difference between putridity and rancidity, with most people thinking that "rancid" = "putrid". Often, rancid oils look & taste normal, but the partial oxidation renders them toxic -- they become a powerful free radical that likely is the major player in cardio-vascular disease. (Cholesterol is an innocent bystander that gets oxidized and then becomes involved in CVD, but is not a direct cause. It's the rancid oils that are to blame.)

By Brainstorms (not verified) on 27 Oct 2015 #permalink

That pan of bacon looks a little thin. It could do with another 500g or so for my burger

By Doug Alder (not verified) on 27 Oct 2015 #permalink

@6. RickA : "But as Eric says – moderation in everything."

As Socrates apparently said (although obviously in ancient Hellenic) "All things in moderation including moderation."

My second fave quote of his behind only his near last words to his follower Apollodorus :

Apollodorus : “O Socrates how it grieves me to see you die so undeservedly.”

Socrates : “My dear Apollodorus, would you rather see me die deservedly?”

Death by bacon and other tasty meats? There are far worse ways to go! (& we all gotta go someday, somehow, anyhow.)

Good calm informative article here, Greg Laden - thanks.

Stevo, there aren't too many worse ways to go than by rectal cancer. Which makes for about the worst way to go.

By Brainstorms (not verified) on 28 Oct 2015 #permalink

I think that the main question is: Is there better alternative for the red meat?

The red meat is mostly eaten in countries with high life-expectations, and the colorectal cancer is with geriatric prevalence. So if one do not eat meat he is probably not reaching the age when this cancer type is important. And if we eat the same amount of proteins with another food, then we must add the risk of this new protein source.

And another question: Although the full report is to be published, it is clear that this meta-study is performed mainly on epidemiological basis. Is the the meat or the artificial stuff we add to it in order to produce more meat and to make it edible? We almost always eat the meat not crude so the process is always there and it seems it matters (processed group 1, not processed group 2 ==> the processing is cancerogenous).

Well should be good if the authors of the study are lurking around.

The EPIC long term study of diet and ill health is designed to tease out some of the things thsat are difficult to do in retrospective studies by asking the particpants what they are eating regularly for years.

Brainstorm the reason traditional cured meats are pink is because the curing mix includes saltpetre aka potassium nitrate. If you are being iffy about 'chemicals' I suspect that would count, though I hate the use of chemical in that context so I'm not a good judge of such things. On the other hand I do make a mean cured beef ...

Not really, Jazzlet. When I say "chemicals", I don't use the proper, technical term, but the colloquial take: Think rather an organic compound, often not naturally made, and certainly not part of any mammal's diet, that's added for other-than-nutritional or pragmatic food preparation needs.

E.g., artificial preservatives, artificial colorings, emulsifiers, flow agents, anti-caking agents, "mouth feel" enhancing agents.

However, one can certainly turn this inside-out, and condemn a number of industrial foods for what has been taken out instead: A good example here would be flours & associated products made from industrially-produced flour.

Most people don't realize that "bread" as would be familiar in the Middle Ages was nothing like what passes for "our daily bread" today. "Wonder Bread" is a only a wonder in the breadth of its nutritional abomination. Industry so over-processes wheat today --mainly in attempts to increase storage life of raw materials and shelf life of finished products -- that it's reduced to something that even the bugs won't eat.

Just as industrial processing of foodstuffs adds things that we shouldn't be consuming, it's stripping food of "inconvenient" nutrients. Junk food truly is junk!

By Brainstorms (not verified) on 28 Oct 2015 #permalink

wheelism, the WHO wasn't giving people herpes -- they were only reporting the numbers.

"The bastards" are the ones who want to kill the messengers.

By Brainstorms (not verified) on 29 Oct 2015 #permalink