So: red meat and cancer. According to the WHO, scientists have discovered that yet another standard component of our ancestral diet is terribly bad for you. This is one of the more bizarre assertions in a 50-year history of nutrition-related nonsense: that such an august institution should be putting such a dishonest spin on some rather unimpressive research should worry anybody who cares about scientific integrity.
You can find lots of explanations about how this sleight-of-hand was carried out, but Dr. Alex Petrushevski here gives a particularly engaging (and short) summary of the actual research:
In particular, he gives a good exposition on why correlation is not necessarily causation, why low values of correlation should be treated with extreme caution, and why (in the light of the actual data) red meat isn't even close to being a "carcinogen", as the WHO and other authorities have insisted.
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TheAwfulToad
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Thanks for posting this, I've watched part of it, but I'll have to try to catch up when I'm back from my holidays, as I didn't get chance to watch it all.
I haven't heard of any research that moving towards a plant-based diet has been associated with an increased risk of bowel cancer. So there is nothing lost my moving to a further towards plant-based eating.
Thus the good news should be that, if the current trend of increase in veganism (and others moving in a more plant-based direction) continues, then in years to come nutritional research should be able to provide some very interesting results.
And if it is true that red meat is indeed associated with bowel cancer then presumably bowel cancer incidence should decrease, at least in those moving away from red meat. My guess it will take 20 years for that research to begin to appear. I hope to be around to see that research appearing.
To put some depth onto this, this article livekindly.co/cancer-resear... reports that Cancer research UK indicates that 8,000 cancer diagnosis per year might be avoided.
The article ends by stating, "In a report released last May, the WCRF revealed that a plant-based diet, along with avoiding tobacco and sugary drinks, can reduce cancer risk – including stomach, breast, colon, prostate, and lung – by as much as 40 percent."
I haven't heard of any research that moving towards a plant-based diet has been associated with an increased risk of bowel cancer.
Correct. It's exactly the same as for meat-eaters. In fact there is no statistically-significant difference for cancer generally. You can check a variety of statistics here:
Vegans show a slightly lower rate in some studies, but it's a trivial and elusive result. The problem here is that 'vegan' covers an awfully wide range of diets, as does 'carnivore'. It could be that a smallish number of outliers in both groups are pulling the averages one way or the other: that is, the term 'carnivore' does include a lot of people who eat a disastrous diet, whereas 'vegan' tends to imply people who take a bit more care with their health.
There were 34,952 diagnoses for colorectal cancer in the UK in 2016. Since only 1% of the population identify as vegan, we can take that figure as being the baseline for meat-eaters. If this statement were true:
there could be up to 8,800 fewer instances if everyone stopped eating red and processed meat.
then there would have to be research showing a reliable diagnosis rate 25% lower among vegans compared to meat-eaters. That data simply isn't there. Cancer UK are, at best, misguided.
>>And if it is true that red meat is indeed associated with bowel cancer then presumably bowel cancer incidence should decrease
100 years ago people thought tobacco could only give pleasure, and it's only when people started to do epidemiological studies that it's harmful effects become clearer.
Looks like a similar thing is happening with processed meat. The effect is smaller so it's taken a while to be spotted, but the evidence is building up.
He wasn't presenting any "findings". He was reviewing the evidence on which the WHO based their recommendations, and shows it to be wanting (commonly expressed by the phrase "results do not support conclusions"). Did you follow what he said? Do you understand terminology like "statistical significance"? If not, google them. The underlying ideas are complicated, but the basics aren't hard to grasp.
>> My money's on the WHO
In other words, you'll just believe the most credible authority figures rather than looking carefully at the actual data.
To be fair, I realise most people don't have the training to follow the research, and that bothers me a lot. Science education is woefully lacking these days, and it's not surprising people just listen to whoever has the most recognisable institutional logo behind him. It's one reason I post these videos, which describe how the statistics work in everyday language. My hope is that, by watching this stuff, people who opted out of STEM subjects at school will get a better handle on how science works in general. It's important. We're supposedly living in a scientific age, but we're still bombarded by superstition and nonsense with virtually nobody saying: wait a sec, that's not right ...
Whatever you call them, review, critique, summary or something else he's welcome to submit them to a scientific journal where they can be reviewed.
By and large yes, I do rely on sources I believe to be credible (whether they are 'authority' figures has nothing to do with it), that reliance isn't blind, and is subject to revision if more evidence emergies.
Just because the good Dr claims the WHO is wrong doesn't make it so. Just because he tries to explain statistics to lay people doesn't make his conclusions correct. Just because he says all cause mortality is a better endpoint doesn't mean it is. Just because he's shown a picture of some graphs doesn't mean he's not cherry picked the data to fit his ideology. His claims are subject to critical analysis too.
Think of it in terms of Bayesian priors - before looking at the study myself I'm assigning a correctness probababily to the WHO vs the Dr and I'm ranking the WHO higher.
The WHO monograph is about 500 pages long so it's going to a while to work through.
I tried to eat more vegetables and ended up with the most painful diarrhoea in my life. It took weeks for the bowels to recover from the burning sensation.
Yes. The gut bacteria get all messed up when expected to deal with things like processed meat. After a while, the good bacteria that process whole plant foods die off and are replaced by the bacterial equivalent of weeds. They wouldn't know how to process fiber, so you end up with undigested food in your gut.
Basically, we were born with a Ferrari digestive system, but if given the cheap fuel, it runs like a 30-year-old Yugo. It can be fixed, but if it's too broken it's not simple or easy.
I first heard this claim when I (tried to) watch What the Health. It was one of the many claims they made that had me annoyed.
Even if red meat does cause an increased risk of cancer, it's nothing like as dangerous as smoking. In some ways, saying that makes the risk of smoking seem less severe.
I've since learned more about the study, and it really does seem flawed - the increased risk wasn't that high, they couldn't rule out other factors as being contributory, and they couldn't account for the quality of the meat. I'll definitely listen to your video later, to see if there's any more problems I wasn't aware of.
>> Even if red meat does cause an increased risk of cancer, it's nothing like as dangerous as smoking. In some ways, saying that makes the risk of smoking seem less severe.
Exactly. IIRC Petrushevski makes a joke about that, something to the effect that "I just had four cigarettes for lunch".
Comparing meat with cigarettes makes a mockery of serious science about real carcinogens.
I've managed to listen to it now. His breakdown of the studies. Only 1 of 18(?) studies showed a link between cancer and red meat, and yet we seem to accept that one study is the only correct one. Cherry-picking much?
I've heard the argument regarding processed red meat before (that it tends to be eaten more often by people with an unhealthy overall lifestyle). It would be interesting to see a study on processed meat carried out in Spain or Italy, where processed more often means salami and chorizo, and rarely means burgers with fries.
>>Only 1 of 18(?) studies showed a link between cancer and red meat, and yet we seem to accept that one study is the only correct one. Cherry-picking much?
That's one of the problems when people with little statistical background try to interpret a technical paper.
All studies are not equal. There can be many reasons to give more credence to one study over another. Small sample size, bad design etc and many others.
Simply looking at the total number of studies and looking at how many of them showed an effect is a naive form of meta analysis for which there are more powerful techniques (it's possible for example that no single study shows and effect but once combined the effect is there)
benwl, well stated. Many people state things with no proof at all. For example:
"Even if red meat does cause an increased risk of cancer, it's nothing like as dangerous as smoking. In some ways, saying that makes the risk of smoking seem less severe."
Let's just look at the top ten global cancer numbers from 2018. I'll put a T next to those potentially caused by tobacco, and M next to those that might be caused by eating meat. I'll leave out the less-than-obvious connections such as breast cancer. Of course, I'm providing "no proof at all"; this is just a quick exercise to see if eating meat could potentially be worse than smoking:
All cancers*17,036,901
1 Lung 2,093,876 12.3% T
2 Breast 2,088,849 12.3%
3 Colorectal 1,800,977 10.6 M
4 Prostate 1,276,106 7.5% M
5 Stomach 1,033,701 6.1% M
6 Liver 841,080 5.0% M
7 Oesophagus 572,034 3.4% M
8 Cervix uteri 569,847 3.3%
9 Thyroid 567,233 3.3%
10 Bladder 549,393 3.2% M
So, roughly - and at least - 42% of all cancers could result from eating meat. So maybe - just maybe - the possibility shouldn't be summarily rejected by people who have no more idea than I have if it's true?
The study isn't looking at diversity of cancers though, it's looking at risk. You have something like a 300-400% higher likelihood of developing cancer as a smoker/ex-smoker. Meta-analysis of meat studies showed an 18% increased risk, which can't be ruled out as chance.
You increase your risk of cancer by smoking just 1 cigarette. You increase your risk of cancer from red meat by eating more than 50g per day, every day, for an extended period.
One of the studies mentioned in the video above suggested the increased risk could be as much as 85% from high levels of processed meats, I think, but made the point that people who eat 50g plus of processed meat daily, are also likely to have other unhealthy lifestyle attributes, such as not exercising, drinking lots of soft drinks etc. It's possible the increase is linked to the processed meats, but it's not a controlled study (i.e. the only difference in diet isn't the addition of processed meats). This is why I think it would be interesting to look at other countries where processed meats feature heavily, but aren't primarily consumed as junk food.
In the interests of not playing down the risk of smoking related cancer, I thought I should highlight the risks of smoking. I've not removed any of your Ms.
>> That's one of the problems when people with little statistical background try to interpret a technical paper.
He wasn't "interpreting" anything. He was simply reading out the results as stated by the study authors. I don't know why you keep insisting he should submit this for peer review. There's nothing to review.
Can you point to a specific mistake he has made in the video, or is this just an unsubstantiated ad hominem? I do know a bit about statistics, and I didn't hear him say anything contentious. Did I miss something?
>> Simply looking at the total number of studies and looking at how many of them showed an effect is a naive form of meta analysis
No, it isn't. He's looking at how many did not show an effect. There's an important difference.
>> there are more powerful techniques (it's possible for example that no single study shows and effect but once combined the effect is there)
Yes, you can dredge out an effect if you're determined to find one. This carries its own risks of error. Here's a study with 63,000 subjects, followed up over many years:
This is part of the EPIC study that @Penel mentions. It shows vegetarians (in that particular area) with a 40% higher risk of colorectal cancer than meat-eaters. Should we conduct a meta-study in order to collect more evidence that vegetables are bad for you? Or is it better to recognise that the effect is not large enough to be of practical importance, and probably not related to vegetables per se?
You seem to fundamentally misunderstand how science works. Science is not a court of law, where bewigged authorities make their case and the rest of us have to figure out which one has got it right. I know the media think that, and the government think that, and a lot of nutritionists think that, but it's incorrect. The power of science is that you can know objectively and certainly when something is wrong. A "no effect" result is golden in science: it's what you're looking for.
Here's the thing: even the WHO page that @Penel links to is an exercise in evasiveness and handwaving. Check it out.
"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."
This is why a null result is so useful. If you see no effect, there are no confounding factors to explain. As long as you have a large enough sample size - and the p-value will tell you this - you can be very confident that there really is no correlation between A and B. Get 18 results like this in a row and it's as close as you can get to a cast-iron guarantee.
"High-temperature cooking methods generate compounds that may contribute to carcinogenic risk, but their role is not yet fully understood."
Fair point, but don't you think you'd better evaluate this before listing as one of the mechanisms [another statement further down the document]?
"However, if [my bold] the association of red meat and colorectal cancer were proven to be causal, data from the same studies suggest that the risk of colorectal cancer could increase by 17% for every 100 gram portion of red meat eaten daily."
Well, is it causal or isn't it? Why make a big noise about this if you haven't even attempted to establish causality? Does the word "could" really belong in a supposedly science-based statement?
In the case of processed meat, this classification is based on sufficient evidence from epidemiological studies that eating processed meat causes colorectal cancer.
If this statement were true, it carries at least two predictions: (a) people who eat no processed meats (vegetarians, for example) would have a dramatically reduced rate of colorectal cancer and (b) as Cooper27 suggested, it should show people in Spain and Italy, eating a lot of processed meats, having very high colorectal cancer rates.
Neither prediction is true. EPIC suggests that vegetarian colorectal cancer rates are pretty much the same as anybody else's. Spain and Italy rates are at the European average.
The cancer risks associated with consumption of poultry and fish were not evaluated.
And nobody thought this might be highly relevant information? Say, to pin down the assertion that heme iron is a possible mechanism?
And after all that noise, the WHO suggests that there's no good reason to stop eating meat, or to eat less of it.
So what was the point? If I were being cynical, I might think the whole exercise had no other purpose but to keep a whole lot of superfluous scientists and bureaucrats employed, and provide some column-inches for the newpapers.
There's another side to this that bothers me. Let's say Cancer UK are right, and that if every Briton stopped eating red meat, 34,000 colorectal cancer cases would be reduced to 25,000. Well: what's causing the other 25,000?
There is an EPIC study which looked at results from several European countries. As you have said, an unhealthy life-style plus a lot of processed meat equals a poor outcome.
Easy to understand the video and easy on the brain.
My view is that all meats are healthy. I don't see why some people on here say that processed meats are bad. I eat hams, bacon, salami, things like that and am fine.
I don't smoke, but I know of people who died from it.
My view is all meats are unhealthy. I don't see why some people on here say that meats are healthy. I eat a wholly plant-based diet and am fine.
I don't smoke now but I did during the years while I was at University. Stupid me! I did not know then that smoking increases the risk of arthritis. What did I develop after University - arthritis? Stupid me. Had I known in the days that I was already at elevated risk (because of genetics, because of Yellow Jaundice aged 13), had a love affair with dairy, then I might not have smoked. Stupid me!
Except I wasn't stupid. I worked on the based available evidence to me at the time. At the time I did not know that smoking created health risks for me in later life.
Now I know better. I know that a wholly plant-based diet has the power to reverse atherosclerosis. I know equally there is research that a wholly plant based diet without oils can lead one to be heart attack proof.
But it is a free world. If instead you want to place your bets that meat does not cause atherosclerosis, that's your choice. There is not a single research paper showing that consuming meat reverses atherosclerosis. Equally there is no research showing meat can make you heart attack proof.
>> I know equally there is research that a wholly plant based diet without oils can lead one to be heart attack proof.
You're welcome to believe whatever you like, but I post videos like this one because I don't think unfounded beliefs have any place in official policy. Politicians, by and large, don't know much about science, and they're as easily bamboozled as the general public.
I sincerely hope your infallible shield against heart attacks isn't real - because if it is, then the next option down the list of probabilities is cancer, and I wouldn't wish that on anyone. Remember, we all have to die of something.
Worse than just dying quickly and cleanly (which I guess we all hope for) is long protracted illnesses. Athersclerosis leads to both. We don't get to choose a heart attack and quick death.
Of course if you don't accept athersclerosis as an issue, then I guess that makes you heart attack proof. So we both win!
Very informative WebMD article, much of which is incontestible, imo. One statement I like to contest is "Treatment
: Once you have a blockage, it's generally there to stay. With medication and lifestyle changes, though, plaques may slow or stop growing. They may even shrink slightly with aggressive treatment.
"
For this I bring evidence such as this dresselstyn.com/site/study10/ where Dr Caldwell Esseltyn summarises his work on athersclerosis showing, in peer reviewed research, that athersclerosis can be reversed.
If I can quote from that article, "Beginning in 1985 I initiated a study of seriously ill coronary artery disease patients. Their nutrition became plant based without oil. Their cholesterol levels plummeted. Their angina disappeared. Their weight dropped. I have reported this study at 5 years, 12 years, and 16 years, in the peer reviewed scientific literature and again beyond 20 years in my book Prevent and Reverse Heart Disease. In some of the patients we had follow up angiograms (x-rays) of previously blocked arteries demonstrating striking disease reversal, which is a testament to my often quoted statement “The truth be known coronary artery disease is a toothless paper tiger that need never exist and if it does exist
it need never progress.”
A toothless paper tiger. If there is any truth in that statement then why, of why are we still having people having heart attacks or other illnesses from athersclerosis.
The WHO is not saying red meat is worse than smoking. Isn’t that a rather dishonest spin?
Here’s a bit from their Q&A on the matter:
7. Red meat was classified as Group 2A, probably carcinogenic to humans. What does this mean exactly?
In the case of red meat, the classification is based on limited evidence from epidemiological studies showing positive associations between eating red meat and developing colorectal cancer as well as strong mechanistic evidence.
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.
8. Processed meat was classified as Group 1, carcinogenic to humans. What does this mean?
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 the development of cancer in exposed humans.
In the case of processed meat, this classification is based on sufficient evidence from epidemiological studies that eating processed meat causes colorectal cancer.
9. Processed meat was classified as carcinogenic to humans (Group 1). Tobacco smoking and asbestos are also both classified as carcinogenic to humans (Group 1). Does it mean that consumption of processed meat is as carcinogenic as tobacco smoking and asbestos?
No, processed meat has been classified in the same category as causes of cancer such as tobacco smoking and asbestos (IARC Group 1, carcinogenic to humans), but this does NOT mean that they are all equally dangerous. The IARC classifications describe the strength of the scientific evidence about an agent being a cause of cancer, rather than assessing the level of risk.
Yes, it was hyperbole, but I was lampooning the media take on the issue, not the WHO as such. The newspapers have been routinely running headlines like that, eg.:
I agree that they have not understood the classifications. Nevertheless, to be in Class 1, a substance must actually have an observable carcinogenic effect. The definition of a carcinogen is a substance that reliably causes cancer, and the definition of a Class 1 carcinogen implicitly suggests a known mechanism; if you don't have a mechanism, it's a bit premature to state incontrovertible proof.
1) The lifetime risk of colorectal cancer (diagnosis rate) in Europe is about 6-7%. For vegetarians, the most optimistic statistics suggest 5-6%. Now compare that observation with the lifetime risk of lung cancer for smokers (13%) and non-smokers (0.3%). That's what a carcinogen looks like. If meat's presence or absence barely makes any difference, the word "carcinogen" is completely inappropriate.
2) There is no known carcinogenic mechanism for either red meats or "processed" meats (note that this category contains a wide range of products with significant differences between them).
The WHO have stretched their evidence to make it fit their narrative and completely ignored evidence from large, well-conducted studies (eg., the EPIC study mentioned) which find no statistically-significant correlation between cancer and meat consumption, nevermind "probable" causation. Given the evidence they have on hand, it belongs in Class 3: investigated, case dismissed.
To be fair, this thread is the first time I've seen the two separated out - any time we're given advice, the two tend to be lumped together as "red and processed meat".
What I didn't realise - it was mentioned in passing on the WHO summary - is that white meat hasn't even been properly investigated. I was under the impression that it had been investigated and shown definitively to have no effect on colorectal cancer.
Thanks for posting this, the discussion has also been very interesting. There’s been some terrible dietary advice over the years and this is just more of the same.
First of all...are You THAT Awful......Didn't think so!
Secondly, as regards statistics, let me give you the Same information in two ways. Suppose that a new, and deadly, Influenza Strain suddenly 'hit' the population. Scientists do their, very best, and actually manage to 'save' thirty percent of infected people.
The two 'Headlines'..... 1. "Scientists 'Miraculously' SAVE, over a quarter, of infected people." 2. "Despite sciences, best efforts, nearly two thirds of 'flu victims DIE." Both of these Headlines, are actually, essentially true. That IS the Problem with statistics and, dare I say, Newspapers. Have you ever noticed how say, The Mirror and The Mail- both report a Government Minister's Resignation- for example.
The same, is True, with people......Tom stumbles, and falls, landing badly and needs a plaster cast. Paul sees the accident and tells Carol- in the card shop. Carol tells Megan, who 'pops in' for some more butter. Megan tells Polly, who tells 'Big' Sarah, who tells 'Hubby' Brian, who tells Larry, Bob and John in the Local. Given a few days, several versions, of this 'Story' are circulating. In one Tom is 'Mugged', in another he is Drunk, in another actually 'instigated' a fight..... Strangely, it isn't until Paul relates the 'occurrence', to the Vicar- who asks Parishioners, to Pray, for Tom's recovery- that anyone knows the actual truth.
Finally a little 'Funny', for you---- A chicken, and a frog (not a toad....sorry) walk into a library. The chicken walks around saying 'Book, Book, Book, Book', whilst the frog, walks behind saying 'Read it, Read it, Read it, Read it'.
Did you know that 'Eight-five percent, of statistics, are made up...on the spot'?
If it's not too late- still in January- Happy New Year (I'm Sure Not to much) TheAwfulToad.
Basically, if you want to be 'Really' safe... Lose Weight, don't smoke- especially Not Red Meat!!!
Jokes apart , it Was Interesting, to listen to someone who Did Actually Know what he was talking about. There should be More, like him, in the Media- that way we would all be Far better 'informed'.
Thanks for sharing TheAwfulToad who, I'm sure, Isn't THAT 'awful'.
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Black bean and Lentil curry with Red and Wild rice. 
Well no XMas meat for me unless...
