Tag Archives: meat

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 โ€œinadequateโ€ 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.

Americans should eat less meat, sugar, refined grains

The US Office of Disease Prevention and Health Promotion, Department of Health and Human Services, has issued a report recommending that Americans eat less meat. The executive summary of the report is here (pdf), and the web site for the report is here. It says,

The overall body of evidence examined by the 2015 DGAC identifies that a healthy dietary pattern is higher in vegetables, fruits, whole grains, low- or non-fat dairy, seafood, legumes, and nuts; moderate in alcohol (among adults); lower in red and processed meat; and low in sugar sweetened foods and drinks and refined grains. Vegetables and fruit are the only characteristics of the diet that were consistently identified in every conclusion statement across the health outcomes. Whole grains were identified slightly less consistently compared to vegetables and fruits, but were identified in every conclusion with moderate to strong evidence. For studies with limited evidence, grains were not as consistently defined and/or they were not identified as a key characteristic. Low- or non-fat dairy, seafood, legumes, nuts, and alcohol were identified as beneficial characteristics of the diet for some, but not all, outcomes. For conclusions with moderate to strong evidence, higher intake of red and processed meats was identified as detrimental compared to lower intake. Higher consumption of sugar-sweetened foods and beverages as well as refined grains was identified as detrimental in almost all conclusion statements with moderate to strong evidence.

The Problem With The Global Food Supply: New Research

Emily S Cassidy, Paul C West, James S Gerber and Jonathan A Foley, from the University of Minnesota Institute on the Environment, have produced a very important study for IOP Science Environmental Research Letters. (This is OpenAccess so you can access it openly!) You know Emily as one of the participants in our CONvergence panel on food last July. The research Emily and her colleagues do is some of the most important work being done right now, because it is about the food supply.

ResearchBlogging.orgThe bottom line is this: When we look at our food supply, we find that a large amount of what is grown in agricultural fields does not make it into the stomachs of people. There is a lot of waste, there are problems with delivery and distribution, and so on. But what this study looks at is the percentage of potential calories that go to non-food final products, or do get into our diets but do so in a way that significantly reduces the efficiency of the system. There has been a huge increase (percentage wise) in how much field crop is used for biofuels instead of food, but the total amount now is still only 4%. Also, one could argue that this is good use of field crops if the production of biofuels reduces carbon emissions (which is only partly the case). More importantly, a huge amount of the corn and other crops (but mainly corn) that is grown is used as animal feed, and only about 12% of that, in terms of calories, ends up in the human diet. The reduction is because as we move up trophic levels, energy is taken out of the flow.

This graphic from Cassidy et al shows the distribution of calories across food and non-food destinations:

Figure 2. Calorie delivery and losses from major crops. Calories delivered are shown in green (this includes plant and animal calories) and calories that are lost to meat and dairy conversion as well as biofuels and other uses are shown in red.
Figure 2. Calorie delivery and losses from major crops. Calories delivered are shown in green (this includes plant and animal calories) and calories that are lost to meat and dairy conversion as well as biofuels and other uses are shown in red.

The graphic at the top of the post is also from the paper, and has this caption: “Figure 1. Calorie delivery fraction per hectare. The proportions of produced calories that are delivered as food are shown.” The thing to note here is the unevenness across the globe in efficiency of calorie production-to-plate. There seems to be a latitude effect, and I wonder if that has anything to do with the environment and seasonality. But the largest contributor to this variation in efficiency is probably simply the amount of meat in regional diets. As Emily points out in the video that accompanies the paper, even small changes in dietary practices can result in large changes in ultimate agricultural productivity.

We, as a species, need to eat less meat. In particular, certain groups of people, like Americans, need to eat less meat. So let’s do that: Eat less meat!

As an aside, Emily is a friend and colleague and I’ve been really impressed with her work and have been very excited to see these important results coming out. Go Emily! (And co-authors, of course.)


Cassidy, Emily, West, Paul, Gerber, James, & Foley, Jonathan (2013). Redefining agricultural yields: from tonnes to people nourished per hectare IOP Science, 8 (2) DOI: 10.1088/1748-9326/8/3/034015