WHO Says Meat Causes Cancer?

grilled meatsDoes Meat Cause Cancer?

Last October, the World Health Organization (WHO) released a two-page report entitled Carcinogenicity of Consumption of Red and Processed Meat, warning the planet that processed meat definitely causes colorectal cancer in humans, and that red meat “probably” causes colorectal cancer in humans. The report listed a total of 20 scientific references. WHO’s frightening anti-meat proclamation made headlines worldwide and had a major impact on how people think about meat and health. While plenty of pro-meat critiques of the WHO report have been published, the majority of those I read took the WHO’s findings at face value and emphasized that the statistical risk associated with eating processed and red meat is very small.

I strongly disagree. I read the report and all of the experimental studies cited in the report. I found no scientific evidence to support the WHO’s anti-meat cries, and I think it is important to set the record straight.

Let me disclose my biases from the start (something WHO committee members should also be required to do). Eight years ago I changed from a low-fat, low-cholesterol, low-carbohydrate, high-fiber/high-plant diet to a mostly-meat diet, loaded with fat and cholesterol and quite low in fiber, and it reversed every health problem I ever had (read my story on the About page). Naturally I was worried that my new meaty menu was going to kill me, so I began digging into the science for myself and lo and behold: there was no evidence that meat increases risk for heart disease, obesity, or diabetes after all. I came to believe, based on my powerful personal experience and my reading of the research, that animal foods (meat, poultry, and seafood), complete with their natural cholesterol and fats, are good for people.

But what about cancer? Is my meat-based diet, which is working so well for me right now, putting me at risk for cancer down the road?

I am a scientifically curious psychiatrist. I love getting to the bottom of things, and my life’s work centers around helping people confront reality, no matter how complicated or unwelcome it can sometimes be. If the truth is that meat makes me feel great now but is ultimately going to do me in, I want and need to know that. Whether you eat meat only occasionally, every day, or are an all-meat zero-carber, you need to know it too, so I dove into the WHO report to see what’s what.

What I discovered was that THE WHO REPORT IS NOT A SCIENTIFIC DOCUMENT. IT IS A POLITICAL DOCUMENT. Politicians can get away with making sweeping statements to the general public that stand on shaky ground. Scientists are held to a higher standard. They are supposed to show their work, and defend their positions as objectively and honestly as humanly possible. After reading the studies upon which the WHO’s anti-meat proclamations are made, I concluded that there simply is no scientific evidence that meat causes cancer in humans.

And I am not alone.

In November 2013, 23 cancer experts from eight countries gathered in Norway to examine the science related to colon cancer and red/processed meat. They concluded:

“…the interactions between meat, gut and health outcomes such as CRC [colorectal cancer] are very complex and are not clearly pointing in one direction….Epidemiological and mechanistic data on associations between red and processed meat intake and CRC are inconsistent and underlying mechanisms are unclear…Better biomarkers of meat intake and of cancer occurrence and updated food composition databases are required for future studies.” 1)Oostindjer M et al 2014. The role of red and processed meat in colorectal cancer development: a perspective. Meat Science 97: 583–596. To read the full report: http://www.ncbi.nlm.nih.gov/pubmed/24769880 [open access]

Translation: we don’t know if meat causes colorectal cancer. Now THAT is a responsible, honest, scientific conclusion.

How the WHO?

How could the WHO have come to such a different conclusion than this recent international gathering of cancer scientists? As you will see for yourself in my analysis below, the WHO made the following irresponsible decisions:

  1. The WHO cherry-picked studies that supported its anti-meat conclusions, ignoring those that showed either no connection between meat and cancer or even a protective effect of meat on colon cancer risk. These neutral and protective studies were specifically mentioned within the studies cited by the WHO (which makes one wonder whether the WHO committee members actually read the studies referenced in its own report).
  2. The WHO relied heavily on dozens of “epidemiological” studies (which by their very nature are incapable of demonstrating a cause and effect relationship between meat and cancer) to support its claim that meat causes cancer.
  3. The WHO cited a mere SIX experimental studies suggesting a possible link between meat and colorectal cancer, four of which were conducted by the same research group.
  4. THREE of the six experimental studies were conducted solely on RATS. Rats are not humans and may not be physiologically adapted to high-meat diets. All rats were injected with powerful carcinogenic chemicals prior to being fed meat. Yes, you read that correctly.
  5. Only THREE of the six experimental studies were human studies. All were conducted with a very small number of subjects and were seriously flawed in more than one important way. Examples of flaws include using unreliable or outdated biomarkers and/or failing to include proper controls.
  6. Some of the theories put forth by the WHO about how red/processed meat might cause cancer are controversial or have already been disproved. These theories were discredited within the texts of the very same studies cited to support the WHO’s anti-meat conclusions, again suggesting that the WHO committee members either didn’t read these studies or deliberately omitted information that didn’t support the WHO’s anti-meat position.
diagram of rodent studies about meat and cancer

The first experimental study cited in the WHO report began with a description of 12 rodent studies showing either no association between meat and cancer or a protective effect of meat on cancer risk. None of these studies were mentioned in the WHO report. All rodents were either pre-injected with carcinogens or bred to be highly susceptible to cancer. (Illustration by Suzi Smith)

Does it matter whether the WHO gets it right or wrong about meat and cancer? YES.

“Strong media coverage and ambiguous research results could stimulate consumers to adapt a ‘safety first’ strategy that could result in abolishment of red meat from the diet completely. However, there are reasons to keep red meat in the diet. Red meat (beef in particular) is a nutrient dense food and typically has a better ratio of N6:N3-polyunsaturated fatty acids and significantly more vitamin A, B6 and B12, zinc and iron than white meat (compared values from the Dutch Food Composition Database 2013, raw meat). Iron deficiencies are still common in parts of the populations in both developing and industrialized countries, particularly pre-school children and women of childbearing age (WHO)… Red meat also contains high levels of carnitine, coenzyme Q10, and creatine, which are bioactive compounds that may have positive effects on health.” 2)Oostindjer M et al 2014. The role of red and processed meat in colorectal cancer development: a perspective. Meat Science 97: 583–596.

The bottom line is that there is no good evidence that unprocessed red meat increases our risk for cancer. Fresh red meat is a highly nutritious food which has formed the foundation of human diets for nearly two million years. Red meat is a concentrated source of easily digestible, highly bioavailable protein, essential vitamins and minerals. These nutrients are more difficult to obtain from plant sources.

It makes no sense to blame an ancient, natural, whole food for the skyrocketing rates of cancer in modern times. I’m not interested in defending the reputation of processed meat (or processed foods of any kind, for that matter), but even the science behind processed meat and cancer is unconvincing, as I think you’ll agree.

Ready? Hold your nose, we’re going in.

The Epidemiological “Evidence” Against Meat

The WHO looked at more than 800 “epidemiological” (more about that word in a moment) human studies of red/processed meat and cancers of all kinds. Of the 16 types of cancer explored, the WHO chose to base its doomsday decree on studies of colorectal cancer only (presumably because the evidence related to other kinds of cancer was lacking).

The Epidemiology of Red Meat and Cancer

Of those 800+ epidemiological studies, a mere 29 were put forth by the WHO as “informative” about the connection between unprocessed red meat and colorectal cancer.

Of those 29 studies, 14 suggested that red meat was associated with a higher risk for colorectal cancer in humans; 15 of them did not.

The Epidemiology of Processed Meat and Cancer

As for processed meat, the WHO chose 27 of the 800+ studies to make its case for the cancer connection.

Of those 27 studies, 18 suggested that processed meat was associated with a higher risk for colorectal cancer in humans; 9 did not.

infographic of 800 epidemiological studies of meat and cancer

The WHO considered over 800 epidemiological studies regarding red and processed meat and cancer. They based their findings on 56 studies relating to colorectal cancer. Of the red meat studies, more than half found no link between red meat and cancer. Of the processed meat studies, 9 were “negative” and 18 were “positive.” Epidemiological studies are not experimental and should not be viewed as conclusive evidence. The outcomes of epidemiological studies should always be tested in experimental trials to confirm that correlations are not coincidental. (Illustration by Suzi Smith)

The Problem with Epidemiological Studies

Epidemiological studies are not experiments; they are untested hypotheses (guesses), and are therefore completely impotent when it comes to the ability to show cause-and-effect relationships between any two things, including things like meat and cancer. The scientific method demands that these guesses then be tested in clinical studies to see whether or not they are accurate.

Here’s an example: let’s say you are interested in understanding what causes alcoholism. You interview 10,000 alcoholics and 10,000 non-alcoholics by giving them questionnaires about their daily habits. You wonder if pretzels have something to do with drinking because your alcoholic grandfather often stumbles in late at night with pretzel crumbs on his shirt. So in your study you include the following question:  “How often have you eaten pretzels in the past two years?”  If you find that alcoholics reported eating significantly more pretzels than the teetotallers, the next day the following headline might appear in the Huffington Post:  “Eating pretzels increases risk of alcoholism.” The story that follows the headline might advise people to eat fewer pretzels to reduce their risk of alcoholism.

Absurd.

epidemiology-cause or coincidence?

Epidemiological studies implying that association is causation frequently result in misleading and conflicting headlines that leave us befuddled about what constitutes healthy eating. (Illustration by Suzi Smith)

Association is not causation. It could be that pretzels cause alcoholism, but it could also be that alcoholics spend more time in bars where there are lots of free pretzels. The only way to know for sure what’s going on is to do an experiment. Feed some non-alcoholics pretzels every day and watch what happens to them compared to a similar group who is banned from eating pretzels. [For an excellent review explaining the limitations of epidemiological studies of meat and human health, please see this article authored by the USDA’s National Program Leader for Human Nutrition, David Klurfeld PhD: Klurfeld DM 2015 Research gaps in evaluating the relationship of meat and health. Meat Science 109: 86–95.]

Regardless, even if you believe in the (non-existent) power of epidemiological studies to provide meaningful information about nutrition, more than half of the 29 epidemiological studies did NOT support the WHO’s stance on unprocessed red meat and colorectal cancer.

It is irresponsible and misleading to include this random collection of positive and negative epidemiological studies as evidence against meat.

The following quote is taken from one of the experimental studies cited by the WHO. The authors of the study begin their paper with this striking statement:

“In puzzling contrast with epidemiological studies, experimental studies do not support the hypothesis that red meat increases colorectal cancer risk. Among the 12 rodent studies reported in the literature, none demonstrated a specific promotional effect of red meat.” 3)Pierre FH et al 2004. Beef meat and blood sausage promote the formation of azoxymethane-induced mucin-depleted foci and aberrant crypt foci in rat colons. J Nutr 134: 2711–16.

[Oddly enough, none of these twelve “red meat is fine” studies, which the authors went on to list and describe within the text of the introduction to this article, were included in the WHO report].

I cannot emphasize enough how common it is to see statements like this in scientific papers about red meat. Over and over again, researchers see that epidemiology suggests a theoretical connection between some food and some health problem, so they conduct experiments to test the theory and find no connection. This is why our nutrition headlines are constantly changing. One day eggs are bad for you, the next day they’re fine. Epidemiologists are forever sending well-intentioned scientists on time-consuming, expensive wild goose chases, trying to prove that meat is dangerous, when all other sources–from anthropology to physiology to biochemistry to common sense—tell us that meat is nutritious and safe.

The Experimental Evidence against Red Meat

A grand total of SIX experimental studies were cited in the WHO report (references 13-15, and 18-20) as evidence that meat causes cancer, four of which were conducted by a single research group (Pierre FH and/or Santarelli RL). Three are rat studies, two are human studies, and one is a rat/human study [a study of rats and humans, not of hybrid rat-human creatures].

Let’s look at each of these carefully to see if there is cause for alarm. If you’d rather cut to the chase, click here to go directly to the summary.

STUDY 1: Red meat in rats

Reference 13: Pierre FH et al 2004. Beef meat and blood sausage promote the formation of azoxymethane-induced mucin-depleted foci and aberrant crypt foci in rat colons. J Nutr 134: 2711–16.

The purpose of this study was to determine whether heme, the iron-containing compound responsible for the redness of red meat, might be the cancer-causing ingredient within meat. The scientists designed an experiment comparing low-heme meats like chicken to high-heme meats like blood sausage:

  • Step 1. Inject rats with azoxymethane, a powerful carcinogen. Yes, you read that correctly.
  • Step 2. Remove most of the calcium from the rats’ chow (because calcium protects cells against heme).
  • Step 3. Feed rats a 60% freeze-dried meat diet containing skinless chicken (low-heme), lean beef (moderate-heme), or low-fat pork blood sausage (high-heme) for 100 days (approximately 10 rat-years)
  • Step 4: Look for pre-cancerous changes in rats’ colons.

Results: All rats, including the chicken-fed rats, developed potentially pre-cancerous changes in the colon. The more heme the meat contained, the stronger the effect was. None of the rats actually developed cancer.

These results would seem to suggest that skinless white-meat chicken can cause potentially pre-cancerous lesions, which is not what the researchers wanted to find. So they went back and examined the chicken chow more closely and found that the chicken chow contained more arachidonic acid and toxic levels of niacin compared to the other chows, and decided to blame these differences for the unwanted results. They never went back to test these theories, so there is no way to know whether the arachidonic acid or niacin were to blame. They did not go back and subject the beef or sausage chows to additional scrutiny, presumably because the results from experiments conducted with those chows supported their desired conclusions.

TRANSLATION: If you inject yourself with a powerful carcinogen, then eat a calcium-deficient, powdered chicken, beef, or pork diet every day for 10 years, and you are a rat, your colon may start to look funny. We don’t know whether or not you would eventually develop cancer.

STUDY 2: Red meat in rats

Reference 14: Pierre FH et al 2008. Beef meat promotion of dimethylhydrazine-induced colorectal carcinogenesis biomarkers is suppressed by dietary calcium. Br J Nutr 99: 1000–06.

This experiment simply builds upon the findings of those in the above experiment by adding calcium back into the 60% meat chow and showing that it completely protects against potentially pre-cancerous lesions. The authors concluded:

“The results support the concept that toxicity associated with the excess of a useful nutrient may be prevented by another nutrient.”

TRANSLATION: Adequate dietary calcium prevents your colon from looking funny if you find yourself in the unfortunate circumstances described in Reference 13.

The WHO offers three possible theories about how processed meat could cause cancer:

“Meat processing, such as curing and smoking, can result in formation of carcinogenic chemicals, including N-nitroso-compounds (NOC) and polycyclic aromatic hydrocarbons (PAH). Cooking improves the digestibility and palatability of meat, but can also produce known or suspected carcinogens, including heterocyclic aromatic amines (HAA) and PAH. High-temperature cooking by pan-frying, grilling, or barbecuing generally produces the highest amounts of these chemicals.” 4)http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045%2815%2900444-1/fulltext

The authors of the next study begin by shooting holes in two of these theories:

Theory 1: Processing meat leads to the formation of “N-nitroso compounds”, which may cause cancer.

Problem with theory 1: This study’s authors point out that when rats are fed a bacon-based diet, which is high in N-nitroso compounds, they DO NOT develop signs of cancer.5)Parnaud G et al 2000. Endogenous N-nitroso compounds, and their precursors, present in bacon, do not initiate or promote aberrant crypt foci in the colon of rats. Nutrition and Cancer 38(1):74–80. [This “bacon doesn’t cause cancer in rats” study was not included in the WHO report].

Theory 2: When meat is cooked at high temperatures, compounds called “heterocyclic amines” (HAAs) can form, and these may promote cancer in rodents and monkeys.

Problems with theory 2: This study’s authors explain that chicken cooked at high heat also contains heterocyclic amines, but chicken is not associated with cancer risk (and the same is true for fish). Also, the doses of these compounds that cause cancer in animals are 1,000 to 100,000 times higher than doses found in human food.

Both of these highly questionable theories are nevertheless cited in the WHO report as evidence against processed meat.

As for the PAH theory, in case you were wondering, ALL charred, smoked, baked and toasted foods contain PAHs, including grilled vegetables, breads and cereals. In fact, breads and cereals contribute the highest amounts of PAHs to the average person’s diet,6)Bansal V and Kim K 2015 Environment International 84:26–38 but nobody studies the potentially cancerous effects of those, do they?

STUDY 3: Processed meat in rats

Reference 15:  Santarelli RL et al 2010. Meat processing and colon carcinogenesis: cooked, nitrite-treated, and oxidized high-heme cured meat promotes mucin-depleted foci in rats. Cancer Prev Res 3(7):852-64.

This study attempts to understand which aspects of meat processing might be responsible for causing potentially pre-cancerous changes in rat colons. Is it the cooking temperature? The curing method? The type of packaging?

The researchers compared a variety of pork processing methods:

  • light meat vs. dark meat
  • salt curing vs. nitrite curing
  • cooking at 50 deg C (122 F) vs cooking at 70 deg C (158 F)
  • air exposure vs vacuum packing

They pre-injected rats with a carcinogen (1,2-dimethylhydrazine), added the various types of processed meat to calcium-deficient, high-sugar chow, and fed it to rats for 100 days.

The type of processed meat that caused the worst pre-cancerous changes was the dark meat that had been cured with sodium nitrite, cooked at 158 F, and left unwrapped in the refrigerator for 5 days. None of the rats developed cancer.

TRANSLATION: If you inject yourself with a powerful carcinogen, then eat a calcium-deficient, high-sugar diet containing badly-packaged cooked ham every day for 10 years, and you are a rat, your colon may start to look funny. We don’t know whether or not you would eventually develop cancer.

STUDY 4: Processed meat in rats and humans

Reference 18:  Pierre FH et al 2013. Calcium and alpha-tocopherol suppress cured-meat promotion of chemically induced colon carcinogenesis in rats and reduce associated biomarkers in human volunteers. Am J Clin Nutr 98: 1255–62.

In this study, the researchers fed the afore-mentioned badly-packaged ham not just to rats, but to a handful of humans as well. This is important, because, in the words of the researchers themselves:

“One could argue that, owing to its specific physiological diet, the rat represents a poorly fitted model to test an overloaded meat diet. Excess of meat in species such as rodents could indeed give rise to some specific toxic pathways that are possibly not reproducible in other species.”7)Pierre FH et al 2007 Carcinogenesis 28 (2):321–327.

Translation:  Rats are not humans. Rats may not be evolutionarily adapted to be able to handle a high-meat diet, the way wolves, dogs, cats, and people are. A mostly-meat diet happens to be responsible for restoring my health, but I am not a rat.

rats are not people

Rats may not be evolutionarily adapted to be able to handle a high-meat diet, and therefore, are questionable subjects in which to evaluate the implications of meat on health. People, on the other hand, have been eating meat for nearly two million years.

AnyWHO…back to the study.

Seventeen healthy men ate 6.3 oz of our friend, the badly-packaged ham, every day for four days. Their urine and stool were then tested for five different “cancer biomarkers” (substances that may indirectly be linked with cancer risk):

  • ATNC (Apparent Total N-Nitroso Compounds)
  • TBARS (ThioBarbituric Acid Reactive Substances)
  • Fecal water cytotoxicity
  • DHN-MA (DiHydroxyNonane Mercapturic Acid
  • g-H2AX (gamma-Histone 2AX)

After eating the ham, two of the biomarkers (ATNC and TBARS) had increased. [When vitamin E and calcium were added to the ham diet, both of these markers remained normal.]

Two other biomarkers (fecal water cytotoxicity and DHN-MA, considered a good marker of oxidative damage) were unaffected by the ham.

The fifth biomarker (g-H2AX, a very reliable marker of DNA damage8)Kuo LJ and Yang LX 2008 Gamma-H2AX-a novel biomarker for DNA double-strand breaks. In Vivo 22(3):305-9, may have even improved slightly after eating the ham.

But two cancer biomarkers rose—that’s scary, right? Not really.

Both of those biomarkers, ATNC and TBARS, have been called into question by scientists:

Regarding ATNC:

The carcinogenicity of ATNC formed in the gut after eating heme from red or processed meat is unknown.9)Bastide NM et al 2011. Heme Iron from Meat and Risk of Colorectal Cancer: A Meta-analysis and a Review of the Mechanisms Involved. Cancer Prev Res 4(2): 177-184

Translation: even if badly packaged ham raises levels of ATNCs in the gut, we have no idea whether ATNCs cause cancer.

Regarding TBARS:

“Although this is an easy and inexpensive method, the use of TBARS test has received wide criticism over the years. The main problem is the lack of sensitivity and specificity, since TBA reacts with a variety of compounds such as sugars, amino acids, bilirubin and albumin, producing interference in colorimetric and fluorimetric MDA measurement. Therefore, TBARS test cannot be considered representative of oxidative stress.” 10)Grotto D et al 2009 Importance of the lipid peroxidation biomarkers and methodological aspects for malondialdehyde quantification Quim Nova 32(1): 169-174

Translation: the TBARS test is useless.

Interestingly, the authors refer to a study (conducted by a different group of scientists) that found vegetarian diets resulted in higher levels of g-H2AX (a very reliable marker of DNA damage, aka mutations) than diets containing cured meat or red meat.11)Joosen AMCP et al 2009 Carcinogenesis 30 (8): 1402–1407 [This “vegetarian diets may cause cancer” study was not mentioned in the WHO report.]

TRANSLATION: If you eat 6.3 ounces of badly packaged ham for four days in a row, your urine and stool will be higher in two substances that have no proven connection to cancer.

STUDY 5: Red meat in humans

Reference 19:  Le Leu RK et al 2015. Butyrylated starch intake can prevent red meat-induced O6-methyl-2-deoxyguanosine adducts in human rectal tissue: a randomised clinical trial. Br J Nutr 114: 220–30.

The authors of this study tried to show that unprocessed red meat causes mutations in human colon cells.

Twenty-three people were asked to include 10.6 oz per day of lean red meat (cooked beef or lamb) plus two cups of orange juice or low-fat milk in their diets for four weeks. These poor volunteers then underwent rectal biopsies, which showed a 21% increase in the number of mutations of a particular type known as “O6-MeG adducts” in their colon cells. [Researchers also expected to find an increase in ATNCs 12)apparent total N-nitroso compounds but this did not occur].

As scary as this may sound, you should know that there is a special enzyme located throughout the body, including in colon cells, called MGMT, whose sole purpose in life is to go around repairing O6-MeG mutations, because these mutations occur all the time as part of daily living. It is only when these mutations go unrepaired that there may be an increase in cancer risk.13)Christmann M et al 2011 O6 -Methylguanine-DNA methyltransferase (MGMT) in normal tissues and tumors: Enzyme activity, promoter methylation and immunohistochemistry. Biochimica et Biophysica Acta 1816: 179–190.

[In fact, in the next and last study we’ll explore, the authors chose a different kind of mutation to study because they specifically acknowledge that colon cancer risk has nothing to do with the number of O6-MeG mutations, but instead is related to low activity of the MGMT repair enzyme14)Lewin MH et al 2006. Red meat enhances the colonic formation of the DNA adduct O6-carboxymethyl guanine: implications for colorectal cancer risk. Cancer Res 66: 1859–65.]

However, EVEN IF these O6-MeG mutations were to go unrepaired, and EVEN IF they were to have the potential to lead to cancer, this study wasn’t designed in a way that can tell us that red meat was to blame. The authors did not report what else the volunteers were eating over the course of those four weeks other than the red meat, milk and/or orange juice. They do tell us, though, that during the high-meat phases of the study, participants ate significantly more protein (19% more) and significantly less fiber (26% less) than during the low-meat phases of the study, therefore the study wasn’t properly controlled.

In the second phase of this study, a special fiber supplement (butyrylated high-amylose maize starch) was added to the diet, and it completely blocked the increase in O6-MeG mutations. [This fiber experiment explains why subjects were asked to add milk or orange juice to their diets—they needed something to dissolve the fiber supplement in. Milk and orange juice have very different nutritional properties (most notably sugar content). If you include beverages in your experiment, you should ask everyone in the study to drink the same beverage and ideally include a control group that doesn’t add the beverage to their diet.]

TRANSLATION: If you include 10.6 ounces of lean beef or lamb plus two cups of milk or orange juice in your usual diet every day for a month, biopsies of your rectum will show a 21% increase in the usual number of mutations in your colon cells. We do not know whether it was the red meat, orange juice, milk, higher protein intake, lower fiber intake, or some other aspect of the diet that led to the increase in mutation rate. These mutations are typically automatically repaired by the body and do not increase your risk for cancer.

STUDY 6: Red meat in humans

Reference 20:  Lewin MH et al 2006. Red meat enhances the colonic formation of the DNA adduct O6-carboxymethyl guanine: implications for colorectal cancer risk. Cancer Res 66: 1859–65.

The purpose of this study was to try to demonstrate the effects of red meat and fiber on colon mutations in humans. Twenty-five people were confined to a metabolic ward and fed one of three diets:

  • a vegetarian diet
  • a low-fiber diet containing 14.8 oz of red meat per day
  • a high-fiber diet containing 14.8 oz of red meat per day

After 10 days, stool samples were tested for “cancer biomarker” ATNC 15)apparent total N-nitroso compounds and for a particular type of colon cell mutation called O6-CMG.

The low-fiber, red-meat diet resulted in higher numbers of O6-CMG mutations than the vegetarian diet, as well as higher ATNCs. Should we worry?

Regarding the ATNCs: we discussed earlier that their relationship to human cancer has not been established. As for the mutations, if you’ll recall, mutations happen all the time, and are not worrisome unless the body can’t repair them.

Regarding the O6-CMG mutations: this study was conducted in 2006, back when scientists thought that O6-CMG mutations couldn’t be repaired by the MGMT repair enzyme normally present in our bodies. However, in 2013, researchers discovered that MGMT is able to repair O6-CMG mutations after all, so we have since learned that an increase in the number of these mutations is not a cause for concern. 16)Senthong P et al Nucleic Acids Res. 2013 Mar; 41(5): 3047–3055.

Furthermore, there were numerous methodological problems with this study.

  • Even though the volunteers were being carefully fed in a supervised metabolic ward, the composition of their diets was not described in the paper. For example, we don’t know how much carbohydrate, protein, or fat they ate. Also, unfortunately, the low-fiber meat group was fed refined carbohydrates in place of high-fiber foods.
  • To make matters worse, if any volunteer started losing weight, he/she was fed buttered marmalade bread to restore weight. We are not told which volunteers received these additional sugary treats, nor how often.
  • There was no non-red meat animal protein control (i.e. chicken or fish). The age and health status of the volunteers were not provided.

TRANSLATION: If you eat a low-fiber, high-protein, high refined carbohydrate diet that includes 14.8 ounces of lean beef or lamb for 10 days, your colon cells will experience more mutations than usual. We have no idea what aspect of this diet is responsible for the increase in mutation rate. These mutations are typically automatically repaired by the body and should not increase your risk for cancer.

The Experimental Evidence: Should you Worry?

I personally think the first three studies of carcinogen-injected rats are not only ludicrous, but irrelevant to human health, and can be dismissed.

I also find the rat-human study of ham unconvincing; the biomarker results were all over the place, and I don’t care about the health effects of dried-up ham.

In my opinion, only the final two studies cited are worth considering, because a) they are human studies and b) they use unprocessed red meat. They both propose that heme, which is what makes red meat red, can increase mutations in colon cells.

Unfortunately, these two studies were not designed in a way that could prove that it was red meat that caused mutation rates to increase, but let’s just say for the sake of argument that red meat increases mutations. There still may not be any cause for alarm, because:

  • Mutations occur constantly as a normal part of everyday life.
  • Mutations are caused by a wide variety of natural stimuli– from within our bodies, from the foods we eat, and from the environment.
  • Our bodies have evolved numerous, sophisticated mechanisms to neutralize mutations.
  • Mutation rates may have nothing to do with cancer risk. [Please see my series What Causes Cancer?].

However, just because these two studies were poorly designed doesn’t mean we should discard the theory that heme might pose health risks to humans. Could heme be the cancer-causing culprit lurking within red meat?

Not according to this 2015 statement written by David Klurfeld, PhD, the USDA’s National Program Leader for Human Nutrition:

“While heme iron can increase cell proliferation in the colonic mucosa of mice and catalyze the formation of N-nitroso compounds in rats, there is no data that normal levels of heme in human intestine contributes to any harm.17)Klurfeld DM 2015 Research gaps in evaluating the relationship of meat and health. Meat Science 109: 86–95

Interestingly, Dr. Klurfeld was one of the authors of the WHO report.

Bottom Line

When you get right down to it, the only plausible evidence to suggest that red meat might be risky to human colon health is contained in two, that’s TWO, human studies, both of which were very small and  poorly designed, and therefore unable to give us useful information about the effects of red meat on cancer risk. These studies are inconclusive at best, and worthless at worst.

Human nature being what it is, believing is seeing.

People looking for reasons to avoid red meat may view these two studies as concerning.

People looking for reasons to eat red meat may view these two studies as reassuring.

It is your choice, of course! I just want you to have the facts so you can make an informed decision.

Trumpeting to the world that meat causes cancer on the basis of these two studies is ridiculously irresponsible and makes a mockery of the WHO. There is ample information to suggest that the WHO’s report is biased, incomplete, and scientifically dishonest.

To reward yourself for making it to the end of this convoluted scientific journey, I invite you to enjoy a more light-hearted take on the WHO report—a poem written in the style of the beloved Dr. Seuss.

If found this article interesting, you might also enjoy the following posts:

Does Carnitine from Red Meat Cause Heart Disease?meat heart An example of how experimental scientists twist themselves into pretzels trying to connect meat with human health problems—and fail miserably.

New Dietary Guidelines Hazardous to your Health? A critique of the USDA dietary guidelines generation process, including clear evidence of anti-meat bias.

The History of All-Meat Diets

Do High-Fat Diets Cause Depression? How the inattention to laboratory animal chow ingredients render most nutrition studies conducted in rodents completely useless.

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  • FromPA

    This is the best critique of this report I’ve seen. I’ve personally given up on WHO, the American Heart Association, the DGAC, or any other entity that’s remotely associated with nutrition (except Credit Suisse, as they seem to know what they’re doing). That is, if they issue nutritional guidelines, I ignore them.

    • Thanks, PA. I agree that Credit Suisse does a phenomenal job of analyzing and reporting about nutrition science!

  • Thanks, PA. I agree that Credit Suisse does a phenomenal job of analyzing and reporting about nutrition science!

  • RIchard Feinman

    This is great. I think back to my original reading of Ravnskov’s book on Cholesterol Myths. My reaction at that time was that it can’t be this bad and I have to go back and read the originals. When I read the originals I found it was that bad or worse. On red meat, I am probably going to take your word for it because it is well discussed and I don’t have the neuroendocrine system for confronting more dreadful science. I do think, however, that the post is not quite right, philosophically, that epidemiologic or other associations cannot support causality. There are criteria for when they can. (It is that the papers you cite do not meet these criteria). Laid out by Bradford Hill, I discussed in blogpost http://bit.ly/21YzaHk and (shameless plug) my book.

    • Dr. Feinman–thank you for reading my take on the (yes, dreadful!) science! Your point re: appropriate application of epidemiology is very well-taken. I just finished reading your blogpost and loved it. I come away not only with a deeper and more sophisticated understanding of epidemiology but also an appreciation for its place in history. And it’s really funny:) As for your book, plug away! I’ll go one step further and actually give away the title: The World Turned Upside Down: The Second Low-Carbohydrate Revolution.

    • DaemonJax .

      Epidemiological studies can “support” causation, but causation can only be proven with other non-epidemiological studies. Epidemiological studies show associations, which may later be proven to have a cause and effect relationship, but how often does that really happen? It’s true that a lack of evidence for causation isn’t evidence of a lack of causal effect, but that isn’t saying much. There’s value in epidemiological studies, but they should not be used as the sole basis of instituting public health policy.

  • Stefan

    Thank you for this great piece of analysis/critique. Apart from not being a lab rat (hurray) I tend to eat grass fed beef as humans would have prior to the invention of subsidised corn and feedlots, and I don’t use industrial oils to prepare it. So one more spanner into the works by asking what kind of meat and what kind of preparation was used? How many more confounding variables does it take to disqualify a study?

    • Dear fellow non-rat Stefan:

      Exactly! I get as much of my meat as possible from a local meat CSA that raises animals naturally and humanely. I know that many people don’t have access to that kind of quality, so I realize I’m fortunate.

      • Cara Brotman

        THe China Study was written by scientists! They’ve concluded meat, ALL meat causes cancer to the human body! WHY DON’T ALL YOU SELFISH PEOPLE LEAVE THE POOR ANIMALS ALONE TO LIVE OUT THEIR LIVES WITH THEIR CHILDREN THE WAY YOU ALL WANT TO DO THE SAME!!! YOU PEOP;LE DISGUST ME! THANK GOD FOR WHO!

        • Dear Cara,

          I have no relationship of any kind with the meat industry and receive no financial support from the meat industry.

          I have read the China Study book, and the study upon which it is based. The China Study was written by a single scientist and is, unfortunately based entirely on the results of a single (albeit very large) epidemiological study, and therefore does not have the power to demonstrate cause and effect relationships between any food and any aspect of health. For more information, please see my post explaining the problems with epidemiological studies: http://www.diagnosisdiet.com/epidemilogical-studies/

          It is a sad but natural fact that many animals must eat other animals for food. I personally obtain as much of my meat as possible from a local CSA where animals are raised naturally and treated humanely.

          I welcome all viewpoints here, but please note that I did not post one of your comments due to vulgar and disrespectful language. If you can rephrase it appropriately, I’ll reconsider it.

          • Bonnie

            I think the China study book is very flawed.

        • Peggy Holloway

          If we did not eat those poor animals and their children, what would happen to them? Livestock producers raise the animals to make a living and could not afford to keep animals that are not sold as food. I suppose we could kill all the livestock animals and those species would then go extinct. In reality, there is a food chain and some animal must die for another to live. Please read The Vegetarian Myth by Lierre Keith, a recovered vegan.

          • Cara Brotman

            Please google a slaughter house and tell me Im supposed to support that insanity!

          • David_Bailey

            Cara,

            The problem nowadays is that medical evidence is muddled with other issues, like what goes on in slaughter houses! You can’t mix the two together.

            For too long vegetarians have joined forces with the medical scientists because they were saying meat was bad, but there is a lot of evidence that the science was all wrong.

            Maybe we should be all vegetarians – but it won’t be for medical reasons. My partner is vegetarian, so at home we eat vegetarian+fish (though our cat eats meat!) – these questions are very confused, and it is better to leave the medical questions to be settled by medical arguments, and the moral arguments to be argued separately. And anyway, how many vegetarians keep cats as pets – they are amazing animals, and given a vote, I am pretty sure they would all vote to be carnivores!

        • Jasmine Leigh

          I have seen several of your responses and frankly they all seem to be very angry, and pretentious. I feel sorry for you in the sense that what another person does affects you so negatively that you feel the need to be so angry and bitter.

          My grandmother has eaten meat all of her life and in her upper 80’s is energetic and healthy….and has never had cancer. I believe that pre-disposition and lifestyle choices BEYOND just eating meat may be involved with cancer.

          What about all of those animals you spoke of? Many of them eat meat…sometimes they hunt and eat the children of their prey. Perhaps you should lead a campaign to punish them?

          Leaving your advice is one thing. But judging others harshly and doing so with hate and anger is another. Try smiling today. Have a nice day.

          • Cara Brotman

            That is so stupid. Leading a campaign to punish animals for doing what they are supposed to do. God dropped US into a garden, NOT a slaughter house. I disagree with everything you wrote.

        • David_Bailey

          Surely it makes sense to separate two issues here:

          1) Is eating meat harmful to us?

          2) Should we eat meat because it involves killing animals?

  • Stephen T

    Dr Ede, I’m grateful to you for cutting through all this and informing the public.
    The WHO is losing credibility. It seems to be pursuing a plants good, meat bad agenda, even if the plants and grains grow in mono-culture fields fed by pesticides. Much of my local meat is from animals grazing freely in fields. Which is more sustainable? Wouldn’t it be good if nutrition was about science instead of promoting one view of the world?
    Thank you.

    • I share your dream, Stephen:)

    • Arturas

      This is such a bad example that can’t find any sense in it. If your beef can be organic so can be the food animals eat i.e. grass. So there is both organic meat and organic plants.

      Have you looked into the resources needed to produce meat vs plants? or how much calories of oil we need to produce 1 kcal if beef and 1kcal of plant food? it is 54 vs 2.2 kcal.

      • Stephen T

        In most of my county animals feed freely and naturally on grass. Crops can’t be grown on hilly, rocky uplands. So, food is produced on land that would have no other use. No pesticides or water used. This is very-low impact meat and it should be encouraged. I wonder what percentage of plant food is so benign?

        • Arturas

          Your Examples fall out of bell curve. anyway, Fruit trees. As benign as they can get.

          + Now back to bell curve. Compare plant based vs meat based to sustain current world population.

          • Stephen T

            I’m afraid that’s badly written, badly punctuated and incomprehensible. It doesn’t appear to address my point about highly sustainable meat from animals grazing on uplands, which can clearly make a contribution to feeding people nutrient dense food.

            As for fruit, most of it has been altered over the years to contain much more sugar than its wild ancestors and is produced using intensive methods with pesticides and water. Fruits that are lower in sugar are okay in moderation, but fruit is over-rated in terms of nutrients and vitamins.

          • Arturas

            good luck and good health.

  • Alice

    Thank you for this terrific analysis of the latest ‘fear mongering’ by WHO. When I first heard about it, I stood farther back and dismissed it out of hand. When diagnosed with diabetes; which I recognize as an unwittingly self-inflicted condition, I did the research and realized quickly the ‘traditional’ approach to ‘treating’ this problem actually exacerbated it; i.e. intent focus on chemically suppressing the most obvious symptom; high glucose levels, and not the insulin response to consuming carbohydrate. I stopped eating carb for six months in a successful attempt to partially rehabilitate my permanently damaged insulin receptors, then added back small amounts of carb simply because I enjoyed eating some veg and by then my body could tolerate it. In other words my glucose levels were normal and have remained so without the use of any medications but rather by adjusting diet, using high quality plant derived nutritional supplements and exercise. My diet is focused on ‘clean’ meat and healthy fats. In order to accomplish this I was required to do a great deal of research and I was disheartened to realize the medical ‘industry’ and institutions we are supposed to respect and trust are; in my opinion, criminal organizations operating cooperatively to simply create profit without consideration of the general health and well being of the public they were originally meant to serve. The USDA and FDA are run by “ex” executives of Monsanto and for the benefit of Monsanto. The CDC and WHO are right in the pot with them and there is no doubt whatsoever of this reality and their collusion with the pharmaceutical industry. It was, after all, the USDA that unleashed “bio food-like GMO substances” on the general public in the first place. When fanning the flames of Ebola hysteria, the WHO claimed there was no cure for Ebola knowing the DOD Threat Assessment Agency had already demonstrated silver nanoparticles could neutralize Ebola and similar viruses. WHO also repeatedly blocked shipments of colloidal silver to Africa where, having done their homework, African nations were trying to import effective treatment for the Ebola outbreak they were experiencing. I believe our ‘health’ organizations have been gutted and something very dark has been substituted for sound medical/dietary guidance and information. As mentioned below, you really cannot believe a word they say and those who are at the very top of the human food chain; pun intended, seem exceptionally intent upon encouraging us all to eat the wrong foods. As you have said, the human body has no biological need to consume carbohydrate therefore it is nonsensical to believe carb should be our primary food. Add the fact literally hundreds of studies have proven sugar; in all its forms, is literally poison to the human body. We are expected to believe our primary diet should consist of plant food which is unnecessary and processed by our bodies as poison? If you feed a cat grain it won’t eat it because it knows grain is not its food, however the cat needs the nutrients in grain. Mice and birds eat the grain and the cat eats the mice and birds. Many different kinds of animals eat every kind of plant food. There are approximately 18lbs of vegetative nutrient in each single pound of wild meat. The animals eat the plants [carb] and we eat the animals. That is how we gain access to those nutrients. Our bodies were never meant to consume these plants directly and I see this as one of the fundamental causes of virtually all ‘modern disease’. Notice our hunter ancestors did not stalk carnivores for food. They hunted the plant eaters … just like the other carnivores. The rivers of insulin created by continuous consumption of carbohydrate disrupts the entire; profoundly complex, human hormonal system leading to the ‘progression’ of ‘diabetes’ into ever increasing destruction of the body. I can only assume the pharmaceutical indoctrination of a ‘medical education’ is generally overwhelming critical thought not to mention common sense. Then someone like you pops up and you are like a breath of fresh air. I am so grateful you have come forward to share/explain and draw attention to issues such as this and to express yourself so clearly for those of us who do not have the medical/scientific training you have but tempered with the aforementioned critical thinking and common sense. Again, thank you.

    • Hi Alice

      Thank you for the many thoughtful and articulate nuggets in your comment–rivers of insulin indeed! Congratulations on having conquered your health problems using logical dietary changes!

    • Evin Tucker

      The mainstream of science insists that fat causes diabetes instead of carbs, most likely because there is an established bias against fat in most health and nutrition circles.

      • Alice

        Careful analysis of studies demonizing fat were done with an obvious bias and it is still going on today. The scientists ‘expected’ to ‘prove’ fat was ‘bad’. They fed two groups: one group with carb; the ‘control’, and one group was fed carb with fat which produced negative results. However, the scientists never even considered the carbs; i.e. it wasn’t the fat doing the harm, it was the carb.

        • That’s exactly right, Alice! The majority of anti-fat studies ignored the presence of refined carbohydrates included in the diets examined, and this is precisely why it appeared on the surface that fat was the villain.

  • Julian Sauma

    it does

  • Dear M.

    I agree that is is tragic for public health officials to have become so obsessively focused on fat and cholesterol–to our peril, as it turned out. Cholesterol is a vitally important molecule to every cell in our bodies. LDL and total cholesterol values are not helpful in determining one’s risk for heart disease. Triglycerides, blood glucose and insulin levels are the numbers to worry about, and all of these are influenced most profoundly by dietary carbohydrate.

  • Laura James

    Also the statistics for risk of getting colon cancer need to be analyzed. If I remember the stats correctly colon cancer affects approximately 5% of the population. Eating more than 50 grams of red meat/processed meats per day supposedly increases risk of colon cancer by 18%. But that is 18% of 5% so it may only add a 1% chance of actually getting colon cancer. Otherwise the risk stats are exaggerated. Sorry if my report of the numbers is off. I’m doing it from memory.

    • Hi Laura

      Yes, you are correct, the calculated risk is quite small (you have an excellent memory: from baseline 4.5% to 5.3%, an increase of 17%), but I would go one step further and say that estimates of risk based on these kinds of epidemiological studies are meaningless. If, as Dr. Feinman points out in his comment and link above, the epi studies relied upon by the WHO had met stricter scientific criteria, and if the majority of them had been pointing in the same direction (i.e. showing a possible link between meat and cancer), and if the magnitude of the effect had been large, we might consider taking the statistical outcomes seriously, but not under these circumstances. Not to mention the fact that Nina Teicholz pointed out last fall that there were two large human clinical trials demonstrating that lowering meat intake for 4-8 years had no effect on cancer risk: the Polyp Prevention Trial and the Women’s Health Initiative. These studies were (of course) not mentioned by the WHO.

      • Alice

        If you’re worried about colon cancer; for instance if you have a genetic vulnerability to it, you might want to consider supplementing with super bio curcumin as well as Meeker raspberry seeds.

  • Evin Tucker

    The evidence I’ve seen seems to indicate that it’s the cooking methods that determine whether or not red meat causes cancer. Overheating red meat has been shown to produce harmful chemicals known as HCAs, which have been shown to possibly cause cancer. However, by taking care to avoid overcooking, and using certain types of marinades and spices, HCA production in meat can be inhibited significantly.

    • Hi Evin

      I agree that HCAs (referenced in my article above as “HAAs” are higher in cooked meats (of all kinds, not just red meat, but also poultry and fish, as described above). However, it appears that the amounts needed to cause cancer in laboratory studies are astronomically high and therefore we may not need to worry.

      • Mark

        Any lab studies in which plants caused cancer for which we ‘may’ not have to worry ?

        • HI Mark,

          This is a great question and one I would like to write more about.

          There are actually many studies demonstrating that plant food ingredients can a) kill healthy human cells and b) cause cancerous changes in human cells. There is even one study mentioned in my post above:

          “Interestingly, the authors refer to a study (conducted by a different group of scientists) that found vegetarian diets resulted in higher levels of g-H2AX (a very reliable marker of DNA damage, aka mutations) than diets containing cured meat or red meat.11) [This “vegetarian diets may cause cancer” study was not mentioned in the WHO report.]”

          There are additional references in my post about cruciferous vegetables as well: http://www.diagnosisdiet.com/is-broccoli-good-for-you/

          • Mark

            So the message is cut back on vegetables and increase the meat and cured meats ?

          • My message is that there is no evidence that meat of any kind causes cancer, so if I were you I wouldn’t fear meat. Generally speaking, I’m a fan of a whole foods pre-agricultural diet (no grains, legumes, or dairy) based on minimally processed ingredients.

          • Mark

            Also the WHI trial does not appear to me to be a good trial as it centred around testing low fat. this would I presume reduce meat but invites a whole swathe of potential increases from more damaging ingredients eg sugar and white flour. In fact fat would be not be something to worry about anyway. Despite this the trial did show some modest improvements in Breast Cancer.
            “For breast cancer, risk was 9 percent lower in the intervention group, although this result did not reach statistical significance. One exception was for progesterone-receptor-negative tumors, for which the risk decreased by 24 percent.2”

          • Mark

            Correction, it would seem that the reduction in meat was not cut and dry in the WHI study
            “The women participants were asked to reduce fat to 20 percent at which level “it was presumed that . . . intake of saturated fat would also be reduced.” However, their intake of red meat, fish and poultry, the major sources of saturated fat and cholesterol in the standard American diet, remained nearly unchanged.”

          • tkent26

            Both saturated fat and cholesterol have been red herrings and pretend boogeymen all along. The “evidence” against these nutrients is even weaker than the “evidence” against eating meat.

    • Cara Brotman

      OH YA THAT’S IT! IT’S THE WAY YOU COOK IT that determines weather or not it will kill you! LOL! There has been a 20 year study done by Cornell University and the findings were conclusive! Meat and other animal products CAUSE CANCER! But go ahead and eat it, there’s way to many people in the world and by eating meat you are helping to lower the population by dying an early death. This “Dr” Ede must be on the meat industries payroll.

      • I am not on any industry payrolls and have no relationship of any kind with anyone from the meat industry. The study you are referencing (the China Study) was an epidemiological study, unfortunately.

      • Stephen T

        Try to think like an adult and stop writing in capitals like a angry child. Sensible vegetarians must be cringing at your bad manners and foolishness.

  • E.G.

    Thanks Dr. Eade. Once again your well researched articles has to put rest another one of my concerns. I tried to calculate how much time it must take for a piece like this. It’s well appreciated.

    I’m curious what you eat in a typical day. Are you zero carb or more ketogenic in your eating style. What do you eat besides meats (eggs, dairy, any veggies)?

    Thanks again.

    • Hi EG

      Thank you for your kind comments–it does indeed take a long time to do this kind of work so it makes it all worth it when I hear that people find it helpful! This particular project took a few weeks to prepare, but because I work at Smith College as a psychiatrist during the academic year, those few weeks can take a few months…

      A typical menu for me includes fatty animals, supplemented from time to time with brined olives, occasional low-sugar berries and low-carb vegetables that agree with me (primarily low-carb squashes like zucchini, mushrooms, lettuce, spinach, cucumbers), and low-carb yam noodles (“Miracle Noodles”) usually with a spoonful of pureed pumpkin and some herbs for sauce. I occasionally drink a glass of red wine and do drink a half cup of coffee most days (I don’t think these are perfectly healthy but there you have it). I am sensitive to eggs and dairy, so I don’t eat those foods. I aim for max 30 carbs per day, and some days eat zero carb. I do eat a ketogenic diet and I limit my protein to 60 grams per day.

      • E.G.

        Thanks for the insight. I’ve pretty much went zero carb and my body continuously thanks me for it.
        Look into Shritaki products. They’re made from the fiber of the konjac root. You may be fine with them? They make them in “rice, noodle and spaghetti” forms and they’re kinda cool how they can fill a void and allow you to enjoy those foods. They have zero net carbs, no food energy or gluten. They actually don’t taste like anything but you can jazz them up.
        Final question: do you limit your protein because of gluconeogenesis or some other reason? I’m eating more on zc but I’m not really concerned with what my ketone measures are. I’m feeling great and consistently losing weight at almost double my keto calories. If there’s a health threat on the other hand (kidneys or whatever) from too much protein (I have about 100g/day (Male 5’10” 180lbs) then I will decrease.
        Thanks and take care.

        • Hi EG

          Yes, Miracle Noodles are the same type of noodle exactly, made from the konjac root! I love them and use them nearly every day. I don’t know what I’d do without them. Great minds think alike:)

          I limit protein because in my case, overeating protein raises my blood sugar, causes carb cravings, and takes me out of ketosis. This is apparently not true for everyone, but some of us are more insulin resistant than others. Your protein intake is within the range of what your body should need and you are clearly doing great! There are no kidney risks from animal protein, luckily: http://www.diagnosisdiet.com/food/protein/

          • E.G.

            Thanks Dr. Ede,
            Much appreciated.
            This is as good a time as any to let you know that I have a crush on you. I’ve said it in other forums so it’s only right that you know it as well. 🙂

          • Aw, shucks:)

  • Udo Butschinek

    Very often you read headlines like “Red meat increases cancer-risk by 30%!”. Where “30%” is a mere factor of 0.3 which is close to zero. So even the found correlation is rather weak.

    Regarding the “red meat”-discussion. Without knowing the “science” behind all this, it simply does not make sense that e.g. “white” meat like chicken is healthier than red meat while “red” beef is healthier than pork.
    Isn’t it all immediately digested and split into amino-acids and fatty-acids? How would the body know its source and react differently to it?
    What could be the possible biological mechanism?
    I think that those “scientists” couldn’t give a proper answer to that.
    Asking simple questions like this does the trick to me: It has to be bullshit.

    • Hi Udo

      Exactly. The only difference scientists can point to so far that could explain the difference between red and white meat effects on the body is that darker meats are richer in iron.

  • Dear Mostafa

    It is true that many Asian cultures were much healthier than many western cultures before the introduction of western foods to their diets. However, the most important and most dangerous new ingredient that was exported from the west to the east was refined carbohydrate, not animal foods. We have all been eating animal foods for hundreds of thousands of years. Refined carbohydrates are very new, very unnatural, and very toxic.

    The China Study was an epidemiological study and therefore powerless to show cause and effect.

  • Mark

    Do you really want to invite colon mutations on the basis that you body ‘can handle it’. you also left out the fact that even the high fibre meat diet invoked mutations

    • Hi Mark,

      As I say in my post above, some people will use the uncertainty generated by these poorly-done studies as reassurance that meat is ok (like me) and others will use the uncertainty generated by these poorly-done studies to avoid meat (like you). I don’t judge either viewpoint or strategy; I just want people to have the information so they can make their own decisions.

      Unfortunately these studies were not designed in a way that can prove that meat causes mutations, so I’m not convinced that it does. However, even if meat does cause mutations, I fall into the camp that a) doesn’t believe that mutations cause cancer and b) believes these mutations would be easily corrected. I realize others think and feel differently, of course.

      • Mark

        My feet are not in the genetic mutation theory of cancer either and my meat decision is not really based on studies specifically looking at meat. I take a more general approach in that I look at those populations who live the longest and healthiest and they tend to either not eat meat or eat it only occasionally and ‘quality’ meat at that.

      • Walter David Zitzkat

        OMIGOD! Are you saying “Correlation does not equal causation?” That is the Mantra of Stat 101, and generally the only thing that statistics challenged individuals remember about statistics. I asked you before what your statistics background is? You did not answer. I have had LOTS of stat courses, not to mention calculus, physics and biology. As I said, I am a lawyer, not a scientist, but I work with many scientists, including nutritionists.

        Let me ask you one very important question: if, as seems to be your opinion, that major long term longitudinal studies of large populations are worthless for showing causal relationships, then why are places like Oxford, Harvard, Cornell and other universities doing them? And why is the NIH and other organizations funding them?

        The clinical studies which you seem fond of also have uncontrolled variables, like the one I cited previously about “Vegetarians being more prone to cancer than non-vegetarians.

  • Mark

    Animal products create inflamation through bacterial toxins present in meat, saturated fat is thought to boost the absorption of these toxins into the blood stream. A whole food plant based diet is the only diet that has been proven to reverse heart disease the number one killer and yet you seem to be pro meat ?.

    • Dear Mark,

      Yes, I believe that meat (by which I mean any type of meat–whether it be poultry, red meat, or seafood) is vital to human health. Of course it is best if that meat is naturally, humanely, and cleanly raised.

      Unfortunately none of the plant-based diet studies claiming to reverse heart disease were not conducted in a way that can tell us whether the elimination of animal foods played any role in the results. This is because these studies did not simply eliminate animal foods. They also removed refined carbohydrates (the number one risk factor for heart disease, in fact), and many of the studies also manipulated numerous other variables as well. There is more information about plant-based diet research in this post as well as a list of references: http://www.diagnosisdiet.com/diet/vegan-diets/

      • Mark

        What this means for people with heart disease is they either follow a whole food plant based diet which has been proven to at least halt and in cases reverse HD or take a chance and throw some meat into the diet which as you said may or may not be one of the culprits. Now if you had heart disease what would you do, take a chance and include meat or simply go for the diet that has shown long term benefits. Its clearly a no brainer, unless someone shows an Ornish or Esseltyn style diet with meat works just as well you have to go with their approach

      • Mark

        Also may I ask if meat is ‘vital’ to human health why is it that whole food plant based eaters such as 7 day eventists are probably the longest living goup of humans. Surely if meat was ‘vital’ for human health they would not occupy this coveted position ?.

        • Any diet beats the Western diet. If the studies of adventists you refer to compare the lifespans of people eating whole foods (plant-based or not) to those of people eating the Standard American Diet, then it’s simply not a fair fight. Those will always demonstrate a benefit in comparison to people eating the Standard American Diet. Unfortunately there are no studies of whole foods diets containing meat to whole foods diets without meat. If you send me the study you are referring to, I’d be happy to look at it.

          • Mark

            That is not an answer to my questionDr Ede, please reread my question and the one below

          • Mark

            Let me be even clearer I am not comparing Seven day eventists to the SAD. What I am saying is that the blue zones tend to be no meat or low meat consumers. If meat was ‘vital’ to health then you would expect a wholefood meat eating community to eclipse them all. In fact the words ‘vital’ would suggest that these bluezones would not even get into the top 6 let along hold all positions. The use of the word ‘vital’ is simply ridiculous and does not hold up.

          • tkent26

            None of the blue zones are vegan. They don’t eat processed crap. They get lots of exercise. They have balanced levels of sleep, sun exposure, and stress management. They have deep social/cultural/religious ties. Within the context of all that, it’s pure reductionism to focus on a specific percentage of meat, fat, or carbohydrate.

          • Mark

            Some are veggies others eat meat sparingly eg special occasions and yes I would agree that the occasional meat is grass fed and unprocessed.

          • Walter David Zitzkat

            I have been a vegetarian for about 40 years. During that time I have downhill skied black diamond pistes all over the world, run marathons, fathered two children who have never eaten meat in their lives, been an adjunct professor in law school and gotten a black belt in Shaolin Kempo Karate. My BMI is under 25, have been practicing law for decades, and am still doing that as a full time job.

            What Vital thing did I miss out on?

          • tkent26

            Because it worked for you, therefore this one particular diet should work the same for everybody? There is “one true diet to rule them all”?

          • Walter David Zitzkat

            There are some dietary facts that are certainly true for all. E.g. that eating meat is correlated with higher rates of cancer and heart disease.

          • tkent26

            The Mormons are a more omnivorous group with a similar social-cultural profile. They live as long or longer than SDAs, on average.

          • Walter David Zitzkat

            Sorry, but that conclusion is both simplistic and un substantiated. Can you please tell me how you know Advantists eat only whole foods (animal or not) or how you know that eating whole foods makes you healthier. (Please provide link to studty.)

        • tkent26

          Confounded by religious ideology.
          Confounded by numerous other diet and lifestyle factors.
          Based on self-reported food surveys.

      • Walter David Zitzkat

        Do you have a link to the actual study you are referring to? I would like to read its methodology and conclusions.

    • Cara Brotman

      Right on Mark! These people are so brainwashed by the meat industry!

    • Walter David Zitzkat

      Amen!

  • Tony

    I stumbled across your we site thanks to your article on the Psychology Today website. I had been consuming a largely “plant based” diet for a number of years with the result being high blood pressure, GERD, chronic bowel problems (likely IBS), and the inability loose weight. I had recently “doubled down and was nearly 100% vegetarian, but my problems kept getting worse, and my weight was on an uphill increase with no solution in sight. After reading through your website, I thought what the heck, I’ll try a meat only diet for a week or so with relatively low expectations (I believed my bowel problems were due to a problem of fat absorbtion, and thought that I probably would see these worsen). Much to my surprise, my problems hace actually completely resolved. I also sleep better and no longer snore (my wife thanks you for that). My weight is also on the downward trend, and I have lost my large belly in a very short time. (Interestingly, the total pounds I have lost are realtively small so far, the the difference on my body and clothes is huge). I am now a strong opponent of the “one size fits all” strategy for healthy eating that predominates our culture today. Although I personally know a large number of people who have had sucess on plant based diets, this is an eating strategy that does not work with my metabolism. Thanks for all of your research into this! -Tony

  • Beefeater

    Thank you for this rebuttal of the latest Who anti red meat report. I really enjoyed reading and pleased someone linked me to it in a comment on my Facebook Post recently.
    I have always believed since childhood that beef from grass and cruciferous vegetables such as cabbage, somehow protected against cancers. This was anecdotal folk law passed down through generations of my ancestors involved in cattle and grass husbandry in the 1950’s, in the UK Roman Wall country of Northumberland.
    In the 1980’s newspapers reported a cancer inhibiting agent in fried ground beef, fed to mice, trying to prove the opposite. This was only published once and I actually cut it out of I think the Globe and Mail. Shortly after this industry driven research by Western Grain feeding interests led to Experiments at local Experimental Farm, Nappan, Nova Scotia, trying to prove the identified cancer inhibiting agent, believed CLA’s, were enhanced in the Rumin of fattening cattle by feeding Soybean and Barley grain mixes.I know this because we were experimenting in grass fattening cattle as in my youth in UK and with my veterinary Daughter, reasoned the ground beef from such would contain high levels of Omega 3’s, similar to cold water fish from the greens of the sea. Department of Ag, not interested but Fisheries tested for us. (see lindenleas.ca) Subsequently it has been proven in trials around the world that CLA’s are related to Rumin fermentation of greens, not grains and are believed to be cancer protecting. Further recent evidence indicates that gut, soil and plant microbes of fermentation such as lactobaccilous are connected in the CLA’s production and consequentially related to human health in inhibiting or protecting against cancer.

    • Walter David Zitzkat

      Well, I am glad at least that you credit your “beliefs” to folklore and legend, not to science, as well as to “newspaper” reports, not scientific journal reports. You believe what you want to believe.

  • Bonnie

    Thank you, Dr.Ede for all your hard work! It’s amazing to see these good “official ” organizations trying to brainwash people. Thank you kindly for shining a light on the truth.

    • Cara Brotman

      Meat causes the human body to become constipated, for starters. Now thats the first negative affect hitting the body, how is that good??

      • Bonnie

        Nice blanket statement Cara…??
        I eat meat everyday and I am not constipated. I am Not sure what you are doing, to be so constipated?…but it is certainly Not the meat.
        ( unless you’re speaking about processed chicken nuggets?.. which we are not)
        Humans are made to eat meat.
        There are many civilizations who eat only meat. People who live in deserts and in the arctic, etc.
        & I’m not sure why you wrote this towards my comment?

        Any human, stranded in the forests of Canada for a couple weeks – esp. in the winter, would have only fish or meat as a food source. That is nature.

    • Walter David Zitzkat

      Are you sure you would know the truth? Basically if you ignore the top studies by the best scientists you are ignoring the truth. You believe what you want to believe, even when science says the opposite.

  • Cara Brotman

    Meat eaters believe what they want to believe so they can continue eating meat. Plain and simple, how can eating a diseased, rotting piece of meat that has been through hell it’s entire life, with it;s vibrational level on hazard, and tell me that is good for my body!

    • tkent26

      If you are eating diseased, rotting meat, then something is wrong with your refrigerator, or you kept it _way_ past the expiration date.

  • vlp

    You claim to use science as a measure of all of the papers you have scrutinized, yet you are not a scientist. Thousands of scientific papers have been published that support the case for limiting or eliminating animal-based diets, with very few that support your point of view. Why not be honest and say that the science is not 100 percent conclusive? You claim others are cherry picking the science to support their view, while that is exactly what you are doing!! Why not admit that you love to eat the flesh of other living beings, you love the taste and perhaps you get a psychological thrill from doing something that is cruel and shameful, something I believe is an aberration. Even if an animal based diet was found to be not implicated in disease, it is still wrong to slaughter innocent animals and to eat them–not when there are mountains of luscious plant foods to choose from that easily support a healthy lifespan. The evolution of human consciousness requires us to reject animal consumption, and until we all realize that fact we are on a trajectory to certain extinction.

    • David_Bailey

      Vlp,

      I guess as you wrote this, you had already forgotten most of what Dr Ede actually wrote – such as the fact that the WHO took 800 studies and selected just 29 to go into its report – a selection which totally misrepresented the fact that most of those 800 studies found nothing dangerous about eating meat!

      You can’t combine the moral aspects of meat consumption with the medical ones. In deciding whether to eat meat you have to decide one issue and then the other, and if you conclude that the two questions have conflicting answers, you have to decide which takes precedence.

      • Walter David Zitzkat

        The studies I quote and use do not consider moral arguments, only health arguements. EVERY MAJOR STUDY EVER DONE STATES THAT THERE IS A CORRELATION BETWEEN EATING MEAT AND CHRONIC DISEASES. Period. End of story.

        • tkent26

          Some major studies state that there is a weak and inconsistent correlation between some types of meat and some chronic diseases. Based on self-reported food surveys, and confounding with dozens of variables. But reporting tiny absolute risks as big relative risks sure makes it sound scary! Same statistical shenanigans that pharma uses to sell statins.

          Do tell us, what does every major study have to say about consumption of fish/seafood? Doesn’t that count as “meat”?

          • Walter David Zitzkat

            You are sounding like a broken record. “self reported food surveys” and “confounding dozens of variables.” How about being a little more specific (or even better, scientific) and giving links to exactly what studies you are referring to and exactly what you mean?

    • tkent26

      Vegan alternative facts, perhaps there is a job for you in the Trump administration. Go sell your puritanism somewhere else.

      • Walter David Zitzkat

        Long term studies following a large population for hears are not Puritanism, and if you do not know the difference between statistically valid science and religion, there is no point it talking to you.

        • tkent26

          Declaring that “meat and fat are bad”, and trying impose this ideology on others is puritanism.

          If you like large, long-term studies, do tell us, what were the results of the Women’s Health Initiative?

          • Walter David Zitzkat

            Give me a link to this study and its methodology, as well as who paid for it.

    • Walter David Zitzkat

      First of all, let me simply say that I agree with you for the most part. I am a vegetarian for ethical, not health reasons. However, I do enjoy the health benefits of being vegetarian. I am not a scientist, but I am a lawyer, and I know a crappy argument when I see on. I am not chrerry pickng. I select only the top studies, large population longitudinal studies over a significant time period. Cherry picking is to ignore the major studies in a field, such as Epic Oxford, and to select dubious meta-studies or small studies with a small population being followed from a clinic, where the people being studied had major health problems to begin with. To give you one example, I would reject a study that I read some time ago that concluded that Vegetarians are more likely to get cancer than non-vegetarians. Reason: Patients who were vegatarian and non-vegetarian were studied in a cancer clinic. The only problem with the study was that the people who were vegetarian became vegetarian AFTER being diagnosed with cancer. If you don’t understand why that study should be ignored, then I really don’t know what to say.

  • David_Bailey

    I find it remarkable that modern science seems to have gone astray on so many issues:

    The idea that meat is bad for us.

    The idea that saturated fat causes heart disease.

    The associated promotion of polyunsaturated fats as a ‘healthier’ alternative’.

    The idea that salt is dangerous at the sorts of levels people are likely to consume it.

    The concept that heart disease is primarily caused by cholesterol.

    The claim that statins are free of serious side effects.

    The neglect of the Warburg effect in theories about cancer.

    The process of science seems to have become horribly corrupted – first they make strong claims on very weak evidence, and then refuse to back down as the evidence points the other way.

    • Beautifully stated, David. You should share your thoughts more widely. Are you on twitter or facebook?

      • David_Bailey

        No, I belong to a generation that didn’t get hooked on social media! However, since I did chemistry to PhD level (many years ago), I do take an interest in what has happened to science. I think science generally is in big trouble. I also got bitten by statins, which explains my interest in medical science!

  • Walter David Zitzkat

    I really cannot believe you ignored every major longitudinal study ever done, and have relied upon clinical trials. If you are a doctor of medicine, you should be aware that your medicine may be killing your patents. Here are some major studies stemming from the Framingham study in the 1940, large longitudinal studies following large populations, and continuing to this day which clearly show you are wrong.

    The Epic Oxford Study – Oxford University Professor Tim Key:

    https://www.youtube.com/watch?v=SSanovEeIsk

    The Seventh Day Adventist Study – Loma Linda University

    http://publichealth.llu.edu/adventist-health-studies

    Harvard School of Public Health Study – processed meat

    https://www.hsph.harvard.edu/news/hsph-in-the-news/report-finds-processed-meats-can-cause-cancer/

    Harvard L-Carnitine Study

    https://www.facebook.com/HarvardHealthPublications/posts/10151650046601159

    The China Study – Cornell MIT

    https://www.cancertutor.com/china-study/

    Harvard Red Meat Study

    https://www.hsph.harvard.edu/news/press-releases/red-meat-consumption-linked-to-increased-risk-of-total-cardiovascular-and-cancer-mortality/

    Other studies:

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2974007/

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2803089/

    https://www.sciencedaily.com/releases/2012/09/120911091658.htm

    https://www.ncbi.nlm.nih.gov/pubmed/26780279

    I could easily give you 50 more studies

    I have two questions for you:

    1. Why do you ignore longitudinal studies of large cohorts of thousands of people studied for many years and instead rely upon small studies of a few people over a few days?

    2. What exactly are your credentials in statistics for disregarding the above studies and WHO studies and are you aware that for studies such a s Framingham, Harvard Nurses, Epic Oxford, and most of the studies I have cited that there is at least one Ph.D. Statistician assigned to the study to insure lack of bias?

    I should add that the clinical trials you seem to put so much faith in are NOT experiments, in that every relevant factor is NOT controlled, as it would be in a Chemistry experiment for example. The longitudinal studies with large cohorts are prospective studies following a large population, so large that the results can be statistically significant. I urge you to listen to Dr Key, below when he talks about the statistical significance of the results of the Epic Oxford study. Surely you are not going to prove anything with a study of 24 people.

    • tkent26

      Almost all observational studies using self-reported food surveys for data, and riddled with confounding variables.

      “The China Study” is vegan alternative facts.

      • Walter David Zitzkat

        Of course, Oxford and Cornell professors have no idea what they are doing. They have Ph.D.s in nutrition and statistics. Better to listen to someone who did a small clinical study funded by the Cattlemen’s Association, or the Meat and Dairy Association, or by some quack who who statistics 101. If all you know about statistics is that correlation does not equal causality, you are better off not saying anything especially when considering major longitudinal studies such as Epic Oxford, the China Study or Loma Linda.

        • tkent26

          You might want to start with Gary Taubes and Nina Teicholz, who review the history of nutrition research, and how it went so wrong. Numerous rigorous, randomized controlled trials, with human subjects, have found either benefits to low(er) carb, or failed to find benefits of low(er) fat. Start by googling Stanford A to Z and the Women’s Health Initiative. All of the observational studies are plagued by A) self-reported food data and B) confounders such as income, sugar consumption, exercise, smoking, etc, etc.

          Loma Linda? You mean where Seventh Day Adventists fund and carry out studies using SDAs as subjects, and the results always just happen to confirm the particular religious beliefs of SDAs? Weird coincidence.

          • Walter David Zitzkat

            Gary Taubes is a journalist, not a scientist, and although he has a degree in physics and aerospace engineering, that does not make him to any degree an expert on biology and nutrition. The books he and Teichholz wrote are opinions, not science. Also, as I asked below, if observational studies are so useless, why are organizations such as NIH funding them, and why are universities like Oxford and Harvard doing them? I have a solid background in statistics, and I can tell you that NO study will ever control for every independent variable, and the value of longitudinal studies of long duration and large populations is immense. The fact that some observations are wrong and that not all variables are controlled for only make them like any other study that is now a priori. The fact that the Seventh Day Adventists are doing nutritional studies, does lead to a presumption that the study will be biased, since vegetarianism is part of the Advantists’ concept of treating the body as a temple. But that presumption of bias is soon alleviated by the fact that the Adventists’ study only confirms what other large studies show, i.e., that there is a correlation between eating meat and many chronic diseases. I assume that you would accept that the Epic Oxford study and the China Study led by a non-vegetarian professor at Cornell are NOT religiously biased, and the same for the Framingham and Harvard Nurses studies. As for “confounding variables” (I assume you mean not controlling for relevant independent variables.) Tim Key, in the UTUBE I posted above talks about that vary subject. You should watch it. As for the issue of low carbs, you are “confounding variables.” Low carb diets a.) can be vegetarian or even vegan, b.) there have been studies showing the benefits of low carb diets and maintaining a state of ketosis, but c. none of that means that the correlation between eating meat and a higher incidence of chronic diseases disappears in a low carb meat centered diet. Finally, I will leave you with the following thought: Seventh Day Adventists have longer lives as a group than any other group that has been studied. So either God loves them, or there is something to being vegetarian.

  • tkent26

    The idea that dietary cholesterol and saturated fat are harmful is ludicrous. This has been refuted about as thoroughly as anything can be in nutrition science. Even Ancel Keys admitted that dietary cholesterol has no effect on blood serum cholesterol.

    Go ask an anthropologist what was the “natural” diet for humans.

    • Walter David Zitzkat

      How about instead of quacking off about this person’s opinion or that person’s opinion you actually give a link that backs up your opinion. By the way, in my previous post I just referred to an article by anthropologists that appeared in Scientific American.

    • Walter David Zitzkat

      When you refer to a study, give a link. Otherwise you are merely giving your opinion. If you can’t refer to any study, then you have nothing to talk about but opinion upon opinion.

  • tkent26

    Right — human hunter-gatherers in the tropics and other regions of Africa never, ever ate meat, fish, or eggs.
    /s

    • Walter David Zitzkat

      I never said that. They ate what didn’t eat them first. Not having night vision goggles or Bushwacker rifles with 30 shell clips, they were very inartful hunters. Mostly they ate things that didn’t fight back like insects, worms, slugs, and carrion.

      https://www.youtube.com/watch?v=BMOjVYgYaG8&vl=en