Well, here we go again. Each year, like clockwork, the conventional medical establishment mounts an attack against red meat.
For decades, we were told not to eat it because of the cholesterol and saturated fat it contains. When that argument became less convincing, a new one was offered: we shouldn’t eat red meat because it increases production of a compound called TMAO, which causes heart attacks.
Now we’re being told not to eat red meat—and especially cured and processed meat—because it will give us cancer. In a recent report, the World Health Organization (WHO) ranked bacon, sausage, and other cured and processed meats as “group 1 carcinogens,” which puts them in the same category as tobacco, asbestos, alcohol, and arsenic. It also placed fresh red meat in the “group 2A” category, which suggests that it is “probably carcinogenic” to humans.
Of course, this isn’t a new argument; it’s been around for at least 40 years. As far back as 1975, scientists speculated that the consumption of animal products was linked to cancer. (1)
How Strong Is the Evidence Linking Red Meat to Cancer?
However, the evidence supporting this claim has never been as strong as its proponents suggest. I have critically reviewed this evidence on several occasions in the past, as have many of my colleagues. Here’s a list of a few articles and podcasts I recommend reading and/or listening to if you’d like to go deep on this topic:
- Revolution Health Radio: Does Red Meat Increase Your Risk of Death?
- Do High Protein Diets Increase the Risk of Kidney Disease and Cancer?
- Where’s the Beef?
- Will Eating Red Meat Kill You?
- Will Eating Meat Make Us Die Younger?
I realize that many of you don’t have the time to sift through all of that material, so I’ll do my best to summarize the salient points here.
Is eating bacon the same as smoking cigarettes when it comes to cancer?
Let’s start with a critical review of the evidence linking red meat to cancer that was published in one of the most prestigious scientific journals in the world (Obesity Reviews) in 2010. (2) The authors looked at 35 studies that claimed to find an association between red meat and cancer and found numerous problems. Here are some key passages from this paper, with my commentary.
Collectively, associations between red meat consumption and colorectal cancer are generally weak in magnitude, with most relative risks below 1.50 and not statistically significant, and there is a lack of a clear dose–response trend.
Translation: the association between red meat and cancer is not strong (i.e. comparing bacon to cigarettes is absurd), and in fact is often not distinguishable from chance. If red meat really did cause cancer, you’d expect to see a linear (continuous) increase in cancer rates as red meat consumption increased. But that’s not what we see in many cases. In fact, in some studies you actually see a decrease in cancer rates in the people who ate the most red meat. (3)
Results are variable by anatomic tumour site (colon vs. rectum) and by gender, as the epidemiologic data are not indicative of a positive association among women while most associations are weakly elevated among men.
Translation: the studies claim that red meat causes different rates of cancer in different parts of the intestinal tract, and different rates in men and women. For example, in the study I just referenced above (#3), there was an inverse relationship between red meat intake and colon cancer (meaning people who ate more red meat had less colon cancer), but a positive relationship between red meat and rectal cancer. And in an analysis of data from the Women’s Health Study, researchers found a strong (and linear) inverse relationship between red meat consumption and colon cancer. (4) Without a clear explanation of why red meat would be prevent some types of intestinal cancer while contributing to others, and have different effects in men and women, the likelihood of a causal relationship between red meat and cancer is reduced.
Colinearity between red meat intake and other dietary factors (e.g. Western lifestyle, high intake of refined sugars and alcohol, low intake of fruits, vegetables and fibre) and behavioural factors (e.g. low physical activity, high smoking prevalence, high body mass index) limit the ability to analytically isolate the independent effects of red meat consumption.
Translation: the studies linking red meat and cancer are plagued by “healthy user bias.” This is a fancy way of saying that people who engage in one behavior perceived as healthy are likely to engage in other behaviors they perceive to be healthy. On the flip side, people who engage in one behavior perceived to be unhealthy are likely to engage in other behaviors perceived to be unhealthy.
In an ideal world, we would be able to conduct a randomized, controlled trial to determine whether red meat causes cancer. We’d create two groups of people that are relatively similar in age and other characteristics. Then we’d isolate them in a medical ward, strictly control their diet, exercise, and other lifestyle factors, and then feed one group more red meat and the other group less.
Unfortunately, this will never happen. Cancer can take decades to develop, so these poor souls would be living in a ward for at least 20 years. Even if we could find people to volunteer for such a study, it would be astronomically (and prohibitively) expensive.
As a result, we’re left to rely on observational studies to shed light on the question of whether red meat causes cancer. The problem with this is that observational studies do not prove causality—they just demonstrate an association, or relationship, between different variables. Sometimes the association is causal, and sometimes it’s not.
Let’s consider red meat. Regardless of whether consuming fresh and/or processed red meat is unhealthy, it has certainly been perceived that way for the past half-century in the industrialized world. What this means is that people in observational studies that eat more red meat also have a tendency to smoke and drink more, eat fewer fresh fruits and vegetables, exercise less, and engage in other unhealthy behaviors that could influence cancer risk. This isn’t just speculation; it has been shown in numerous studies. (4, 5)
For example, most Americans that eat red meat eat it with a huge bun made of white flour, with a serving or more of other refined carbohydrates (chips, fries, soda) cooked in rancid, industrially processed vegetable or seed oils. How do we know that it’s the red meat—and not these other foods—that is causing the increase in cancer?
The better observational studies attempt to eliminate the influence of these other factors, but in practice that is difficult if not impossible.
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You Can’t See What You’re Not Looking For
What’s more, there are certain factors that are likely to play a significant role in the relationship between any food that we eat and cancer, but to my knowledge, have never been adequately controlled for in any study.
One of these is the gut microbiome. Previous work has shown that the composition of the gut microbiota may directly affect the influence of dietary factors on cancer risk. (6)
For example, Streptococcus bovis, Bacteroides, Fusobacterium, Clostridia, and Helicobacter pylori have been implicated in tumor development, whereas Lactobacillus acidophilus, L. plantarum, and Bifidobacterium longum have been shown to inhibit colon carcinogenesis. (7) Other studies have found that certain species of bacteria were higher in populations with high colon cancer risk, while other species were higher in populations with low colon cancer risk. (8) Finally, a recent paper compared the gut microbiota of 60 patients with colorectal cancer with that of 119 normal controls. The patients with cancer had significant elevations of Bacteroides/Prevotella (both species that are recognized as potentially harmful) when compared to the control group, and the difference was not affected by general patient characteristics (e.g., age, body mass index, family history of cancer), tumor size or location, or disease stage. (9)
We still have a lot to learn about the influence of the microbiome on health and disease, but we know enough already to conclude that it is significant. It is possible—and I would argue likely—then, that the variability we see in studies showing an association between red meat consumption and cancer may be in part due to the status of the patient’s microbiome.
In other words, a patient with a dysbiotic (i.e., compromised) microbiome may be at increased risk for cancer if he or she consumes high amounts of either fresh or processed red meat. But a patient with a normal, healthy microbiome may not be.
There is, in fact, some research that hints at this possibility—though it wasn’t what the study authors intended. A couple of years ago, scientists from the Cleveland Clinic published a paper linking red meat consumption with the production of a compound called TMAO, which has been associated with cardiovascular disease.
That paper was riddled with problems (which I outlined in this critique), including the most glaring one—that several foods, including seafood, increase TMAO production by a much greater margin than red meat. However, there was one section of the paper that I found to be very interesting.
It showed that omnivores who eat red meat produce TMAO, whereas vegans and vegetarians who hadn’t eaten meat for at least a year do not. The researchers claimed that this means eating red meat must alter the gut flora in a way that predisposes toward TMAO production.
However, there’s another explanation that I believe is much more plausible: the red meat eaters are engaging in unhealthy behaviors that lead to gut dysbiosis. This could include eating fewer fruits and vegetables and less fermentable fiber, while eating more processed and refined flour, sugar, and seed oils. All of these behaviors have been shown to be more common in the “average” red meat eater, and all of them have been associated with undesirable changes in the gut microbiota. (10, 11, 12)
Apples and Oranges (Or, Paleo vs. Standard American Diet)
Observational studies are useful for generating hypotheses and identifying general trends. But another limitation they suffer from, in addition to those I’ve described above, is that they aren’t able to detect the effects of crucial differences between study participants.
Consider two different people. One follows a standard American diet, doesn’t exercise much, and has a compromised gut microbiome. The other follows a Paleo-type diet, exercises regularly, and has a healthy gut microbiome. In an observational study looking at the relationship between red meat and cancer, at least 95 percent (if not more) of the red meat eaters in typical studies will fall into the former category. If the study concludes that there is a link between red meat and cancer, the 5 percent of the participants that eat a healthy diet, exercise, and have a healthy gut—and are thus highly unlikely to experience the same impact from eating red meat—will be lumped together with the other 95 percent.
Put a different way, it should be fairly obvious, given what we already know about the influence of diet, lifestyle, and the microbiome on cancer risk, that someone following a Paleo-type diet and lifestyle will not share the same cancer risk as someone following a Standard American Diet and lifestyle, even if they are eating an equivalent amount of red meat. Yet these two groups of people are always lumped together in the studies and media reports. This is a huge problem in research, and it has not been adequately addressed.
What’s the Bottom Line?
Even if you ignore everything I’ve written in this article and accept the WHO report at face value, just how much would your risk of cancer increase if you eat cured and processed meats?
About three extra cases of bowel cancer per 100,000 adults. That means you have about a 1 in 33,000 chance of developing bowel cancer from eating cured and processed meats.
This is a far cry from how much smoking cigarettes, which the WHO now classifies in the same category as eating bacon and salami, increases your risk.
As Professor Ian Johnson of The Institute of Food Research said in an interview with The Guardian:
It is certainly very inappropriate to suggest that any adverse effect of bacon and sausages on the risk of bowel cancer is comparable to the dangers of tobacco smoke, which is loaded with known chemical carcinogens and increases the risk of lung cancer in cigarette smokers by around twentyfold.
What’s more, the report from the WHO classified 940 other agents, along with red meat, as potential carcinogens. In the Guardian article above, Betsy Booren, the vice-president of scientific affairs for the North American Meat Institute, put it in perspective:
The IARC says you can enjoy your yoga class, but don’t breathe air (class 1 carcinogen), sit near a sun-filled window (class 1), apply aloe vera (class 2B) if you get a sunburn, drink wine or coffee (class 1 and class 2B), or eat grilled food (class 2A). And if you are a hairdresser or do shift work (both class 2A), you should seek a new career.
At this point, given what the research indicates, I do not feel that modest consumption of cured or processed meat is likely to pose a significant health risk, provided you are doing other things right (i.e., nurturing your gut microbiome, eating nutrient-dense, real foods, exercising, etc.). I think there is even less evidence suggesting that we should limit consumption of fresh red meat, especially when it is cooked using gentle methods (rather than charring it) and when you eat “from nose to tail.”
Okay, that’s it for this year’s installment of “red meat won’t kill you.” See you next year!
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The major reason not to eat meat is that it is cruel. Factory farms utilize brutal and heart-breaking methods to prepare cows/pigs/chickens, etc. for slaughter.
In addition, animals have as much right to live as humans do.
Everyone in the medical profession needs to visit the ‘Spurious Correlations’ website, tylervigen.com at least once a month.
As well as a good laugh, it might give them sense of caution in assuming that correlation implies causation. e.g.
‘Per capita cheese consumption’ correlates with ‘the number of people who died by becoming tangled in their bedsheets’ 🙂
Who knew, go figure again !
There does seem to be an annual campaign to spread disinformation about the “dangers” of eating red meat, almost always accompanied by a push to replace meat with other protein sources (as if protein were the only reason to eat meat). As if on cue, a chorus of voices is touting vegetarian, vegan, and now “plant-based” diets.
Just yesterday, I heard a certain well-known doctor/author promoting a vegan diet on a public radio show. He made statements like (paraphrasing) ‘on average vegans are the healthiest people you will find.’ He urged people to replace red meat (and all meat) with plant-based meat substitutes, describing them as a technology that has made great advances. Here’s the problem with that: people are wrongly using this report to advocate replacing a whole food (meat) with a highly processed one (meat substitutes). The new landscape of meat substitutes include “frankenfood” moniker-worthy ingredients such as textured vegetable protein, typically made from soy that has been subjected to an extrusion process that uses high amounts of mechanical and thermal stress to achieve a texture that is palatable.
What happens to the nutritional compounds in plant foods when they are subjected to these modern food-science processes? Have the effects of these ingredients on human biology been studied by people not tied to the food industry? Doubtful in any meaningful capacity. Worse, I think a lot of these processes are hidden from consumers, who simply see agricultural ingredients like wheat or soy in the ingredients listing, and don’t realize what those ingredients were put through to look, feel, and taste like meat. But they are supposed to replace a whole food like meat, that humans have been eating for countless generations?
Yes, there are risk factors that go along with meat that we need address. First and foremost is that factory farmed animals make up the overwhelming majority of our food supply. Chris has addressed this and other issues over the years better than I can ever hope to. Does the WHO report take into account the differences between factory farmed meat and traditionally raised meat? And do the people using this incomplete report to tout vegan diets talk about the significant nutritional deficiencies people can face when eliminating all animal food sources? The guy on the radio yesterday didn’t mention either of those things. There was also no discussion of how small the increase in absolute risk is, how it can easily be outweighed by lifestyle factors, and there were misleading statements of equivalence to tobacco risk. I suspect there is a lot of misinformation being spread around right now that purports to be proven by the WHO report, and that does a disservice to public health.
Hey Chris, ever since the WHO report came out I have been waiting for your response so I would have something easy to refer folks to. I am more and more convinced that vegetable/fiber consumption is the missing piece in any conversation about health. For people with other high risk factors for prostate cancer, however, I would probably focus a little more on getting them to eat more nutrient dense options and less bacon.
I also would say that I advocate for a rather moderate consumption of meat compared to a lot of paleo dieters I see on IG, etc. I eat it often, but in much smaller servings than the typical american 8 oz steak. I probably got about 2 oz in the chili I ate for lunch, along with tons of butternut, kale, tomatoes, and bone broth.
It seems hard for many black and white thinkers to wrap their heads around it, but it seems completely possible that no red meat versus lots of red meat is just the wrong question to be asking.
I agree Sarah.
Unless recovering from hypoglycemia, lots of vegetables along with small amounts of (clean, sustainable) meat works well for me and my family. My son does fine on more carbs than my daughter and I, but we all do well with the basic “lots of veg, small amounts of fruit, nuts and meat/protein foods”.
Your diet sounds delicious, along with budget-friendly and ecologically sound!
I recently saw the documentary Cowspiracy which exposed the significant effect that the meat industry is having on the environment. They suggested that eating meat, or fish for that matter, will not be sustainable for the planet due to the massive environmental damage that it’s causing; more than any other pollutant or environmentally-damaging practice out there. I wonder if these anti-red meat studies/campaigns have anything to do with this – trying to get people to limit their consumption of red meat from a health standpoint vs blatantly saying that it’s an environmental issue.
I can’t ever imagine being a vegan but the documentary made some interesting points, particularly on sustainable grassfed-type farming and dairy/eggs, that have me thinking on possibly reducing my consumption of animal products. I eat a moderate amount of grassfed meats and cold water fish, maybe 4-6 times per week, and it has improved my health so I cringe at the fact of reducing that amount now, for environmental reasons.
Anyways, love the posts Chris! Maybe you can debunk this issue! 🙂
4-6 times per week definitely sounds moderate, and supporting more sustainable farms means I think you are doing completely fine from an ethical perspective. I think it is important to balance eating the healthiest diet for you and the healthiest diet for the planet, and thankfully completely vegan agriculture is not necessarily the most sustainable solution. One book I found helpful in my thought process around this is called “Meat: A Benign Extravagance.”
Another thing I try to remember is the importance of political change, not just personal–no matter what you eat, who you elect and the policies you support make a much bigger difference to the environment. I couldn’t function even on a well-planned vegan diet, and I don’t believe I have a moral imperative to stay sick–unless we also have a moral imperative to commit suicide to prevent overpopulation.
I do wish more people in the paleo community were talking about being participants in a sustainable ecosystem. If all of the folks advocating a paleo lifestyle could put a little energy into replacing big grain subsidies with some vegetable subsidies, think what a difference we could make!
Sarah: those are good points. Another book that I found interesting was “The Vegetarian Myth” by Lierre Kieth- (I think that’s her name?) She also explains why mono-crops are NOT a good solution for the environment, and how it destroys whole ecosystems. Frankly, I think some of this “sustainability” talk is a bit of brainwashing on the part of certain big companies (like Monsanto) to “guilt” us into eating their way!
Based on all I’ve heard and read, it seems like small farms, with both plants and animals (pastured of course), and “slow food” are the best options, not only for health but for sustainability.
Is this citing all beef from all sources, or are there any distinctions between pastured raised/grass-finished vs. the typical CAFO beef that we know to be garbage anyway? Just curious, since no delineation is mentioned.
If it was the difference between CAFO meat and grass-fed that made the difference, I think chicken would have shown up as a potential carcinogen too, because the biggest difference is the fatty acid profile (higher omega-6 to 3 ratio in both beef and chicken that are fed grains.)
Of course no mention in these study, demonizing red meats, about feedlot raised animal versus pastured organic….
Go figure
Mike,
I basically asked almost the same question in the comments about one minute later than you. Frustrating when no effort is made to distinguish the CAFO beef from the grass-fed/grass-finished organic beef…
most people eat CAFO meat. So on a aggregate basis I suspect making the distinction between CAFO and organic in the study would produce little difference. But you are right, it would be interesting to see a study looking at different disease rates between organic and CAFO eaters.
This is correct, and it’s why it isn’t addressed in large epidemiological studies. Maybe someday…
Diversity of healthy unprocessed foods are a great approach to keeping your body working the way it should. Too much of any one thing, be it healthy or not, is never ideal…
Just eat real food 🙂
Chris, your article is really only saying that we cannot be sure that meat is the main contributor to cancer when looking at meat eaters. This is true but what we can say is that populations that do not eat meat have much lower incidence of cancer and heart disease. Now faced with your argument that PERHAPS meat is not the culprit in these studies versus an examination of populations that do not get high rates of disease I would plump for the latter even if by adopting their diet I am throwing out meat when I PERHAPS need not. Many people will read this and see it as an endorsement of meat which I think is a risky path to take.
Do you think that maybe the populations of people that are studied that do not eat meat and have a lower incident of cancer is because this population of people is generally more health conscience? That they live their lives as a whole in a healthier way than the average American eating meat? I do not think by any stretch that meat causes cancer. I do think that many meat eaters do not source quality meats, do not cook it correctly (aka: burning/charring), and perhaps generally do not live a health lifestyle overall. I think that the results are skewed by the studied population’s other lifestyle factors that contribute to their cancer risks.
Hi Candice, you may well ‘think’ this to be true but personally I would not spend a lifetime eating red meat, albeit with other good health habits, to find out whether meat is a contributing factor or not. I do not mind possibly throwing a few babies out with the bath water if bottom line I live longer. The problem with Chris’s article is that he cannot prove that meat is harmless any more than the the WHO can categorically prove that its harmful. With regard to grass fed meats posted by another poster I agree that they may well be more healthful but most people are unable to access them confidently so again my advice would be to skip meat and stop rolling the dice.
Hi! You’d think skipping meat would help but I did that and my gut health CRASHED hard.
That is an interesting perspective. Thank you for sharing. I understand your point as to proof of what does what or what is responsible for what in our bodies. I do think the quality/source of meats matter. And I also think that red meat provides healthy nutrients that is more difficult to obtain an absorb from other sources. But, that is just my opinion. I eat red meats along with every other kind of meat. I have heard several people say that after eating read meat after being vegans for a long time their health improved. That is neither here nor there…I think for now I’ll keep my babies and the bathwater. I wish to you good health and longevity! 🙂
I think you are correct Candice. I believe eating like our ancestors is better for us. I also however, have come to the conclusion that as far as eating Paleo is concerned some indigenous populations ate a 95% protein diet and other populations ate a 85% vegetarian diet so lets not assume that we all need to eat diets dominated by a diet of meat or poultry. However, let me emphasize that I do eat red meat, poultry, salmon, sardines, pork etc….but also try to eat plenty of vegetables and fruit while limiting my intake of breads and potatoes (diabetes runs in my family) so that I maintain healthy blood sugar levels. I appreciate your sincere and thoughtful comments.
Mark,
First of all, your argument is non-sensical, and could just as well be applied to ANY food group. Humans are OMNIVORES, and as such, have the capacity to eat meat, as well as other food sources. As for “healthiest” populations, for the UMPTEENTH time, they were the Inuit, the Maasai, and the Hunzas, until we introduced crap food to them…. The Inuit and Maasai diets were PREDOMINENTLY animal in nature.
I cannot get hold of any of their meat from my local supermarket sadly
Personally, I didn’t come here for your advice. I came for Chris’s.
Marc, if you have read Chris’s book “The Paleo Cure” he breaks down the nutrient density of red meat (grass fed) just to prove how beneficial it actually is for you.
I believe cancer is a far more complicated disease than many realize. And I think it’s very difficult to “tease out” one factor from epidemiological studies that may or may not contribute to it- (not to mention the whole “correlation doesn’t equal causation” issue). I’ve read a lot on the subject, and frankly, I don’t think anyone really knows for sure what causes cancer in the first place. I ate a mostly plant based diet for many years- (a so-called “healthy” diet, no junk food), only to get cancer. People are naive if they think (like I used to) that a vegan diet will “save them from cancer”, but unfortunately, this is the message the media puts out. I now eat a Paleo style diet, along with bacon and egg every day. And I feel much healthier than I ever did before! (And 6 years cancer free). I have learned from my experience that quality of life in the present is most important; so, I won’t be changing my diet any time soon.
Many thanks, Chris, for another thoughtful, balanced report. For all our sakes, let’s hope obstreperous readers will refrain from leaving a bunch of negative comments here.
Opposing or even challenging points of view are not negative any more than taking an opposing view to big Pharma could be classed as negative. I find lively contrary debates the more illuminating but sadly many people, perhaps not you, tend to find it threatening even when conducted in a polite and civil manner. Lets not forget that we ended up in this god awful medical mess because Doctors are not allowed to question the conventional medical system at least not without consequences.
Thank you! All these articles circulating on FB about meat and cancer are driving me crazy! Just a little knowledge about history and a little bit of common sense goes a long way. Anyway, I posted your article on my FB page and as a response to everyone’s questions and other articles saying meat causes cancer.
Wow!! As per usual excellent post Chris.
On the world cancer foundation to 20 list of countries with highest rate for colon cancer, 14 of them are not high meat consumers , not even Argentina is on the list. This again clearly contradics what WHO is saying.
Looking at markers of inflammation red meat improves homocysteine levels and needles to say glucose levels.
Excellent job the WHO did on creating more confusion in the arena of nutrition.
Thanks again for the great work Chris!!
Yes, I noticed this too. On the list I saw, the 2nd highest percentage of colon cancer was found in Japanese men. Um, hello? Aren’t these the people that are always touted as eating a “mostly healthy, plant based diet?” (Not that I believe that either; I thought they ate lots of fish and rice too). And overall, a woman’s chance of getting colon cancer was quite low.
I fully believe that a high-fiber diet will allow the body to better handle all toxins, if there are dangers to cured meats or even red meat, resistant starch is shown to overcome those dangers.
There is a simple solution! A couple spoonfuls of raw potato starch!
Don’t like the thought of eating potato starch? There’s always green bananas, oatmeal, and inulin to boost fiber intake.
I agree Tim!! Thanks for pointing that out!! I use potato starch. It’s actually tasteless to me. That and oatmeal and it makes a difference I can feel that clearly don’t need a complex study to tell me otherwise.
I think we need more DOABLE information like this and less nitpicking.
We’re here for health yes of course — but most of us also believe in balancing quality of life, along with what just plain and simple pleases the natural senses of the body too. The body knows what it wants and I believe it’s different in different people.
I also know so many healthy people who micro analyze every little ingredient who don’t appear very vibrant, healthy, happy at all either!!
During the summer, there’s nothing like the smell of a BBQ here and there!
Give me a break about the charred!
And it’s very difficult to “always” have “grass fed” where I’m from its very difficult to always have access. I’m sure many others are in the same boat.
And yes Dr Jeff. My grandmother also lived very healthy and vibrant until 92. Ate plenty of bacon, cooked eggs, in bacon grease, never worried about a hamburger, or the bun.
She walked everyday outside. That’s it.
I think the bun also didn’t bother her because in her time the bakers let their bread rise long enough to digest the gluten.
I am not a scientist, and I can’t spout statistics, but I can tell you that life is a terminal condition.
It has also been my experience that the longer we extend human lives the more incidents of cancer you will find regardless of eating habits.
I think we need to quite micromanaging the cancer issue and look at the bigger picture. if you scrutinize just about anything hard enough you will find a correlation to cancer. correlation is NOT cause.
Thanks for the clarity, which is totally missing from the main stream media. My first reaction was that most red meat was from factory farmed cattle who have been pumped up with antibiotics and GMO grain feeds and whose meat is therefore probably loaded with glyphosate residues. Organic, pasture fed meats, such as I try to eat, might have an entirely different impact.
What is interesting to me, is the assumption that red meat from non organic, GMO feed lot fed cattle is healthy to begin with. A study I would like to see (and probably never will) is a comparison between organic pasture raised beef and conventionally raised beef in terms of what happens to the micro biome etc.
Hi Karen,
The study you are looking for might be difficult to find, but if you just assume that non-organic feed lots are feeding primarily glyphosate treated grain products, then you can use studies that show the effect of glyphosate on the human gut microbiome, since the chemical persists, and is carried into the human from the cattle that ingest the grain products. Here’s just one that thoroughly discusses damage to the human body from food-borne glyphosate, both via damage to the gut microbial population and directly.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3945755/
The same authors have a paper on just the alteration of the gut micriobiome, but the following is only the abstract of that document:
http://www.mdpi.com/1099-4300/15/4/1416
You might search just for other works by either of these authors, as they focus heavily on the effects of glyphosate on the deteriorating human condition.
Another factor possibly involved with the red meat and cancer incidence correlation revolves around the Neu5Gc molecule. Neu5Gc is synthesized in almost all other mammals, but not in humans. Red meat and dairy are our prime sources of Neu5Gc. When we ingest it, we incorporate it into tissue. But since we don’t make this molecule, we are capable of producing antibodies against it.
The study of this possible cause of cancer is in its infancy but may eventually turn us more strongly against red meat (and dairy).
http://journal.frontiersin.org/article/10.3389/fonc.2014.00033/full
I addressed that argument here: http://chriskresser.com/does-red-meat-cause-inflammation/ and here: http://robbwolf.com/2015/01/13/episode-253-chris-kresser-red-meat-again-and-neu5gc/
I’m glad to see this discussion opened up here Chris. I’m sure your statements will bring in a lot of additional information from your informed readers and we’ll gain much more from their input.
For instance, I would like to add to your statement “…that certain species of bacteria were higher in populations with high colon cancer risk…” and following that “…patients with cancer had significant elevations of Bacteroides/Prevotella (both species that are recognized as potentially harmful) when compared to the control group…”
I agree with your conclusions that “We still have a lot to learn about the influence of the microbiome….” and “…a patient with a dysbiotic (i.e., compromised) microbiome may be at increased risk for cancer if he or she consumes high amounts of either fresh or processed red meat. But a patient with a normal, healthy microbiome may not be.”
For example, Someone eating a lot of red meat may, on average, also be one who eats far too little fiber, and it’s the lack of fiber that causes the dysbiotic microbiome rather then the red meat.
But my reason for wanting to add to your statement “…patients with cancer had significant elevations of Bacteroides/Prevotella ” is just to strongly defend the species of these two Genera, as your statements imply that “elevation of numbers” is bad, and that may imply that “Any number over a bare minimum is a cause for worry.” I don’t want the reader to come away with the assumption that Bacteroides, for example, are doing the human body a disservice by residing in the gut.
From my studies, Bacteroides, and to a lesser degree, Prevotella are two very important symbiotic genera in the human gut. On average, Bacteroides species comprise usually about 25% of our gut microbiome and continually engage not just in feeding us saturated fats they derive from plant fiber we eat, but also produce vitamins and interact continually with our gut to provide mucosal barrier fortification and even modulation of a variety of host genes.
More here:
http://cmr.asm.org/content/20/4/593.full
So I would liken your appropriate comment about elevated numbers correlating to cancer incidence as being something like relating elevated water in a reservoir to the likelihood of a broken dam. In that case, lest one concludes that any water is a bad thing for a reservoir, it’s better to remind ourselves that generally we want a fairly ample supply of water behind a dam. We just don’t want an excess that can destroy the dam.
So for the bacteria, I wish to emphasize that we all, generally, have approximately a full pound of Bacteriodes species in our gut. If one reads the link I provided though, it is made clear that one species of Bacteriodes, B. fragilis, is very virulent. It causes little problem in the gut, partly because it constitutes just .5% of the total bacterial load, and partly because it behaves at commensally there. But once inside the body, or on the skin, this species can cause great problems. And this is just to show that rather than making sweeping assumptions about our microbiome, based on a fact here and there, we are better served by your advice to just eat whole, nutrient dense foods in portions and proportions as our grandparents did, and not worry so much about the many causes of bowel cancer. And why worry about trying to micro-manage our microbiome? To a large degree that’s out of our hands.
I totally agree with the majority of what has been stated. I used to have numerous bowel problems, diverticulitis being one, that have disappeared ever since I started avoiding sugar and carbs. Even when I accidentally eat a bad piece of fish, which gives me diarrhea, I very quickly rebound because (I think) there are no carbs or sugar for the bad bacteria to survive. In the past (before low carb/low sugar) I would have diarrhea for days before I could get it under control. Now, under the low carb/sugar diet the diarrhea lasts for “ONE” bowel movement and then it ends!! This is something I never thought was possible.
As for meat causing cancer??? I honestly don’t know. But I do know one thing for sure….if I get another Diver infection and end up getting a section of bowel removed my life will be changed forever AND I could still get cancer!! I just had my 5 year lower GI endoscopy. The doctor said that my Diver is there but not red, infected or inflamed in any way. No polyps and no other problems. He told me to eat plenty of fiber and keep doing whatever I’m doing. I told him that I mostly eat meat, eggs, bacon, fish, green beans and salads. He said, “Well, if it works for you??”.
Lastly, ever since I stopped eating sugar and carbs my sinuses have stopped getting inflamed. I’ve had allergies all my life but under this diet it been really great!! The low carb/sugar diet may not be for everyone but it’s the best thing I ever did.
PS – I believe that inflamed tissues are a very good place for cancer to breed or at least exploit weaknesses in the human body!!
treblig
There has been a war between the grain farmers (big agribusiness now) and the cattle industry since the 70’s. I remember the commercials from both of them at the time the first food government food guide came out (guess who won!). Another salvo in this long running and now institutionalized debate. If you ask most people born in the 1880’s to 1920’s (not many around now), they had a heavy meat diet and cancer was relatively rare (my grandmother ate bacon frequently, fried fish in bacon fat, lived in a coal mining town where no grass grew due to coal dust, and she only lived until 99, she was born in 1893). I agree with Chris, don’t panic and throw all that high density nutrition out. There is a lot of good stuff in properly raised red meat and it’s high density nutrition you cannot get from plants alone.
My issue is not the meat itself but could it be the chemicals used to process it. Once upon a time fish like pork was soaked in smokehouses, now a lot of it is dipped in flavourings and dyes. Sausages were made at home or at least by the local butcher, now in factories with all sorts of goodness knows what added. We need to go back to granny’s time when it was home cooked and at least we knew exactly what we were eating.
Thank you…
As someone who works in the culinary field I would say look at countries like Spain, Italy, France, and many others where ‘processed’ meats are staples of the traditional cuisines. I don’t have to tell you what you will find.
Thank you for finally saying what I’ve been thinking all along!
We don’t have to do a controlled double blind study. If there really was a causal relationship between cured meats and cancer then the Spanish and the Italians would be dropping like flies. The only way I can imagine them increasing their cured meat consumption is by taking baths in salami!
That’s not to say that there aren’t serious problems with industrial “cured meat products” in the US. But that has no relevance to me because I only eat food.
On the other hand, when the WHO comes out with a study proving that my uncle’s home cured capocolo causes cancer … I guarantee you I will stop eating it!
This is precisely what I believe. The articles that I have seen written on the WHO study do not delve deeper into the source or processing methods of cured and processed meats.
There has been a war between the grain growers and cattle growers since about 15,000 BC!
Yes BP. At least since the time of Cain and Able.
I like Dr. Jeff’s response Dr. Kessler’s excellent article. I also love the mix of science and common sense. I agree that there is a likelihood that many red meat eaters in the west also indulge in far less healthy ‘foods’ that are processed and full of sugar and that this most likely contributes to any skewed research on the carcinogenic effects of red meat. As far as processed meats, there needs to be a discussion on the difference between today’s processed meats and meats that were processed for hundreds if not thousands of years. How different are the processed meats that we eat in the US from those in Europe and furthermore are the European processed meats still produced in a wholesome manner without added preservatices and chemicals?