DOES RED MEAT CAUSE CANCER?

DOES RED MEAT CAUSE CANCER?

In my opinion, the problem with protein is that every day we hear terrorism the equality meat=cancer and this comes from people who are considered authoritative which clearly destabilizes my ideas about the goodness of meat... What I wonder is: why would certain doctors support the claim that meat leads to cancer ? If it is thought to be untrue, it makes me wonder what is the return for claiming this alleged hoax ??

I received this message from one of our followers. I assume that these doctors really believe that the
meat causes cancer. That is why they wholeheartedly support it.

But why do they believe it?
Because the news came directly from WHO, which most physicians believe to be a reliable source. So they did not delve into whether the supporting evidence was convincing.

Fortunately, there are people who question everything, even claims even from the WHO, if the necessary evidence is not there. In this in-depth discussion we are going to look precisely at the positions of doctors and scientists
that have challenged the evidence on which the WHO (World Health Organization) document rests.

Let's start at the beginning: in October 2015, twenty-two scientists from ten nations met at the Lyon headquarters of the IARC (International Agency for Research on Cancer, an intergovernmental body that is part of the WHO) to assess whether red meat and processed meat were carcinogenic.

Out of that meeting came the one hundred and fourteenth IARC monograph “Red Meat and Processed Meat” (1) which states:
- Red meat is a probable human carcinogen, classified in Group 2A
- Processed meat is a certain carcinogen to humans, classified in Group 1

The media followed up this publication with front-page headlines and prime-time news: red meat gives you cancer.

But is it true?

Let us delve deeper in order to be able to come to our own conclusion based on facts, evidence and common sense. As you know, I believe that critical thinking is crucial to a society that can call itself mature and evolved. Critical thinking is based on the analysis of facts, evidence, observations and arguments to form sound judgments through mental processes.

You often ask me: how can you be so sure of what you believe? Simple: I invested time in informing myself, gathering facts and hard data that allowed me, through a mental process, to come to a solid conclusion. Mind you: solid but not rigid. Mankind's knowledge is constantly evolving, so what I believe to be true today could be disproven by a new discovery tomorrow. So it is necessary to keep an open mind at all times. Science and technology are constantly evolving (fortunately, otherwise we would still have stone wheels)

We begin our information gathering by finding out what and how many groups the IARC divides substances into based on their likelihood to cause cancer:

Group 1, definite human carcinogens, contains 126 substances
Group 2, probable carcinogens to humans, contains 94 substances
Group 2B, possible human carcinogens, contains 322 substances
Group 3, not yet classified as carcinogenic, contains 500 substances
In Group 1 along with processed meat we also find cigarettes and asbestos

On the website of the World Health Organization, on the page of frequently asked questions related to the topic “meat and cancer,” we find this interesting question (2) “Processed meat has been classified as a group 1 carcinogen for humans. Cigarettes and asbestos are also in group 1. Does this mean that processed meat is as carcinogenic as cigarettes and asbestos? Answer: no. Processed meat is in the same group as cigarettes and asbestos but it does not mean it is equally dangerous. The IARC classification reflects the robustness of the scientific evidence on the carcinogenicity of a substance. It does not assess the level of risk.

Extremely interesting information: the IARC places a substance in Group 1 if there is robust scientific evidence that that substance is carcinogenic. It has nothing to do with risk level. To understand it better: alcohol consumption increases the risk of cirrhosis of the liver 7 to 20 times, smoking increases the risk of developing lung cancer 10 to 30 times, consuming meat increases the risk of any disease with which it has been associated no more than 1.5 times. There is an abysmal difference, and many scientists say a 1.5-fold increase is not enough to say red meat is carcinogenic, because there may be other factors at play.

Also on the same FAQ page (2) is another interesting question, “Processed meat has been classified as Group 1: carcinogenic to humans. What does this mean?” Answer: this category (Group 1) is used when there is sufficient evidence of carcinogenicity that the substance causes cancer. Usually the evaluation is based on epidemiological studies showing the development of cancer in humans exposed to the substance. In the case of processed meat, this classification Is based on sufficient evidence from epidemiological studies that eating processed meat causes colorectal carcinoma (cancer).

For one to understand what this statement means, it is necessary to know what an epidemiological study is, how it is carried out and the level of evidence associated with it.

An epidemiological study is called observational, meaning that a population is observed for a specific amount of time. During this time, parameters are recorded, for example, colorectal cancer cases, cardiovascular events, deaths, etc.

There are epidemiological studies that run for decades. The longest of all is the Framingham Heart Study, which began in 1948 and is still active with the third generation of participants.

During an epidemiological study (or at the end of it) we go to see if there is a relationship between a certain clinical outcome (in our case colorectal cancer) and a certain action (in our case consuming processed meat). In technical jargon, this relationship is called correlation: we observe that there is a correlation between people developing colorectal cancer and red meat consumption.

The fact that there is a correlation between two things does not prove that one is the cause of the other. In fact, the rule that any serious and rigorous researcher has well scratched into his or her brain is, “correlation doesn't mean causation.” An epidemiological study cannot prove causation between two events, it can only observe a correlation between the two. To prove that A is the cause of B you have to do an RCT study.

A randomized controlled trial (RCT) is a study where two homogeneous groups of people (with similar characteristics of age, health status, etc.) are taken and followed and analyzed while doing two different things. For example, group 1 takes a drug while the group takes a placebo (a sham drug). If none of the people involved in the study (patients and researchers) know who is taking the drug and who the placebo the randomized controlled trials are called “double-blind.” This eliminates possible personal bias. Not all studies randomized trials are double-blind.

RCT studies are intervention studies, which means you intervene by doing something: group 1 takes a drug while group 2 takes a placebo. They are used to assess causality between A and B. Epidemiological studies on the other hand are observational studies, I simply observe what happens and hypothesize that there is a correlation from A and B. Sorry to repeat myself: epidemiological studies cannot prove causality (that A is the cause of B).

FOOD QUESTIONNAIRES AND SCIENTIFIC EVIDENCE

There is one very interesting thing that is essential to know: when in an epidemiological study it is necessary to detect what the observed population ate, a food frequency questionnaire is used (4).

The questionnaire consists of more than 100 such questions:
1) In the past 12 months, how often did you drink orange or grapefruit juice?
2) In the past 12 months, how often have you eaten peas (fresh, canned, or frozen)?
3) In the past 12 months, how often have you eaten chicken with the skin on?

Possible answers are:
Never
Once or less than once a month
2-3 times a month
1-2 times a week
3-4 times a week
5-6 times a week
1 time a day
2-3 times a day
4-5 times a day
6 or more times a day

Now I ask you: if you were to fill out this questionnaire, do you think your answers would be accurate? Do you remember how often you ate chicken last year? And how many of those times did it have skin??!

Do you think surveying what a population ate through these kinds of questionnaires can be considered reliable?

Another important fact: many questionnaires do not ask about the portions consumed (3) and this can make a huge difference:if we eat too much, we will gain weight, and obesity is a major cause of disease.

Because of the unreliability of food questionnaires, because an observation detected by an epidemiologist might be biased by his or her beliefs, because there may be confounding factors not detected during observation, and for many other reasons--epidemiological studies have a low level of scientific evidence.

In evidence-based medicine there is a system called the “hierarchy of evidence” that ranks the source of a scientific fact according to its level of evidence. Here I report the simplified version published on the Australian government website (5). The most widely used version is that of the Oxford Center for Evidence-Based Medicine (6).

As we move up toward the top of the pyramid, the level of source evidence increases. Epidemiological studies are observational studies and are at the bottom of the pyramid, meaning they have a low level of scientific evidence. Randomized controlled trials (RCTs), on the other hand, have a high level of evidence. While systemic reviews of RCTs have the highest level of evidence.

Notes for nerds

A systematic review is a study that starts from a question “Is saturated fat the cause of cardiovascular disease?” evaluates and summarizes all clinical studies on the topic producing an accurate synthesis that should answer the original question. A meta-analysis is a type of systematic review that synthesizes the quantitative results of RCT studies according to statistical methodologies. A systematic review also analyzes the methodological quality of RCT studies. Clearly, if RCTs are poorly done, the results of meta-analyses and systemic reviews will also be garbage, “garbage in, garbage out.”.

IS THE EVIDENCE REALLY SUFFICIENT?

The IARC monograph states that the classification of processed meat as definitely carcinogenic, “is based on sufficient evidence from epidemiological studies that eating processed meat causes colorectal carcinoma (cancer).”

We have just seen that the level of scientific evidence from epidemiological studies is very low. So sufficient scientific evidence that processed meat causes cancer emerges from where?

In 2014 a study was published (7) where 23 scientists gathered in Norway, after analyzing the various available sources on the topic of cancer and red meat, stated “the epidemiological data on the association that red meat and processed meat increase the risk of colorectal cancer are inconsistent.”.

In 2022, the study “Health Effects Associated with Unprocessed Red Meat Consumption” was published in Nature, probably the world's leading scientific journal.Although there is some evidence that unprocessed red meat consumption is associated with an increased risk of disease incidence and mortality, this is weak and insufficient to make stronger or more conclusive recommendations.

This study is part of Nature's new collection of “The burden of proofs studies”: a new method for assessing the strength of evidence for risk factors and associated diseases. A new tool for evaluating scientific evidence: these studies will provide data for the development of future health, clinical and nutritional guidelines. (8)

But it doesn't end there: a few days (Nov. 22, 2023) ago a study was published (9), also in Nature where it was found that vaccenic acid improves the ability of CD8+ T lymphocyte to infiltrate and kill cancer cells. Analyzing cancer patients, those with the highest levels of vaccenic acid in their blood responded better to immunotherapy. Vaccenic acid--does the name ring a bell? It is found in the meat and milk of ruminants: cows, sheep, goats, etc. And it is also found in human milk. The only way to have vaccenic acid in the blood is to consume foods that contain it.

EVIDENCE CITED BY IARC

At this point, aren't you curious about the “sufficient scientific evidence” that led IARC scientists to classify red meat as a probable carcinogen and processed meat as a certain carcinogen?

To do this I cite the beautiful article (10) by Dr. Georgia Ede, a Harvard-educated psychiatrist who is well known for treating even very serious psychiatric illnesses with the ketogenic diet.

Text in italics is a translation of part of the article by Dr. Georgia Ede.

Dr. Ede's first question is: How is it possible that the IARC came to such different conclusions than the scientists gathered in Norway? Answer: They made irresponsible decisions.

1) They selected only those studies that supported “anti-meat” conclusions while ignoring those that showed no correlation or even a protective effect.

2) The IARC relied heavily on dozens of “epidemiological studies” (which are incapable of proving causality) to support the claim that meat causes cancer.

3) The IARC cited only six experimental studies:
- three on rats that were injected with potent carcinogens before being fed a meat diet (with a protein content 3 times their needs and deficient in calcium).
- three on humans, but with a very small number of subjects and with serious defects in their
performance such as the use of unreliable or dated biomarkers and/or lack of controls
adequate.

4) Some of the theories put forward by IARC about how red/transformed meat could cause cancer are controversial or have already been debunked. These theories have been discredited within the very texts of the studies cited to support IARC's anti-meat conclusions, again suggesting that WHO committee members either did not read these studies or deliberately omitted information that did not support their anti-meat position.

Very heavy accusations I would say. If you want he explains them one by one in his article (10) which you can translate using Chrome or ChatGPT. I will only quote here his explanation related to the epidemiological studies

THE EPIDEMIOLOGICAL EVIDENCE AGAINST MEAT

The IARC reviewed more than 800 human epidemiological studies concerning red/transformed meat and all types of cancer. Of the 16 types of cancer explored, WHO chose to base its apocalyptic judgment only on studies on colorectal cancer (presumably because evidence on other cancers was lacking). Out of 800 studies, only 29 on the red meat-cancer link and 27 on the cancer-processed meat link were considered.

The problem of epidemiological studies

Epidemiological studies are not experiments; they are untested hypotheses (assumptions) and therefore cannot prove cause-and-effect relationships between any two things, including meat and cancer. The scientific method requires that these assumptions be subsequently tested in clinical trials to see whether or not they are accurate.

Here is an example: imagine we want to understand what causes alcoholism. We interview 10,000 alcoholics and 10,000 non-alcoholics by administering questionnaires to them about their daily behaviors. We ask whether pretzels have anything to do with drinking, because your alcoholic grandfather often comes home late with pretzel crumbs on his shirt (Dr. Ede gives this specific example to make the point about how personal experiences can influence studies). So in your study include the following question, “How many times have you eaten pretzels in the past two years?” If you find that alcoholics report having eaten significantly more pretzels than sober people, the following headline might appear in the news papers the next day: “Eating pretzels increases risk of alcoholism.” Nonsense. The association does not imply 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 is going on is to do an experiment. Feed some nonalcoholics pretzels every day and observe what happens to them compared to a similar group that is forbidden to eat pretzels. (

Very often researchers see that a correlation emerges from epidemiology between certain foods and certain health problems, but fifteen times they conduct experiments to test the theory, they find no connection. This is why our nutrition news constantly changes. One day eggs are bad, the next day they are good.

EPIDEMIOLOGY OUT OF CONTROL

Unfortunately, the situation regarding the use of epidemiological studies to make nutritional recommendations to the population is GRAVIOUS. So serious that it has led the highly respected Professor John P.A. Ioannidis of Stanford to write an article (11) entitled “Why most published findings are false.” An article that has been cited 12,672 times, a HUGE number, as I remind you of the 58 million published studies, only 14,500 studies have more than 1,000 citations. (12)

In order for you to understand the seriousness of the situation, I report the results of the study (13) conducted by Young and Karr: we analyzed 12 clinical trials that tested 52 claims that emerged from epidemiological studies. All of them confirmed that there was no evidence for the claims that emerged from epidemiological studies. We repeat this finding: 0 out of 52. In other words, 100% of the claims that emerged from epidemiological studies were false. Actually, in the clinical studies 5 of the 52 prove exactly the opposite of what the epidemiological studies claimed.

I want you to understand why this is GREAT: the nutritional advice that is given to the population is deduced from these very epidemiological studies. It honestly brings tears to my eyes... This is 2023, we feel we are evolved and technologically advanced, but in reality there is not much difference from the Middle Ages.

THE MOST FRUSTRATING PROFESSIONAL EXPERIENCE OF MY VIAT

Professor David M. Klurfeld is head of the National Human Nutrition Program at the United States Department of Agriculture (USDA). His research has focused on the relationship between diet and prevention of chronic diseases such as cancer, heart disease, and gallstones. He has published more than 200 scientific papers and in 2015 was one of the 22 members of the IARC committee that published the monograph on red meat and cancer.

Here are his words (14) regarding his participation in the IARC committee: “It was the most frustrating professional experience of my life. I think most of the scientists present had already decided to affirm a correlation between cancer and red meat even before they had looked at the studies. Several members of the committee were vegetarians, and that from my point of view is a conflict of interest when you are on a committee that writes dietary recommendations, as I think intellectual biases are very strong and should be stated. Like me, many committee members disagreed with the published result, it was certainly not a unanimous vote.”

Scientists are human beings and therefore are influenced by their own beliefs. Following his experience on the IARC committee, Professor Klurfeld published two articles in favor of red meat:

“Humans evolved as omnivores, and it has been proposed that cooking meat allowed the development of larger brains, contributing to our success as a species. Meat is one of the most nutrient dense foods: it provides high-quality protein, heme iron, zinc, and vitamins B6 and B12. Despite these benefits, epidemiological studies have linked consumption of red or processed meat with obesity, type 2 diabetes, cardiovascular disease, and cancers of various organs. Most observational studies report slightly increased relative risks. However, there are many limitations in such studies.” (15)

“Red meat is a nutrient-rich food that provides significant amounts of protein, essential amino acids, vitamins, and minerals. Despite claims by the World Health Organization (WHO) that consumption of processed meat causes colon cancer and that red meat probably causes cancer, the observational data used to support these claims are weak, confounded by multiple unmeasured factors and unsupported by other research needed to reach such a conclusion. About 85 grams of lean meat provides 9% of the daily calories in a 2,000-calorie diet and only 10% of fat, but more than half of the daily requirements for protein, selenium, niacin and vitamin B12, along with a quarter of the iron requirement and nearly half of the zinc needed. These numbers underscore the nutritional density a of red meat.” (16)

NUTRITIONAL DENSITY OF FOODS

This is a very interesting discussion: in addition to calories, a key aspect of the food we ingest is the micronutrients it provides: vitamins and minerals. The priority micronutrients are: iron, zinc, folate, vitamin A, calcium and vitamin B12, if they are missing, our health will suffer. In this interesting study (17) the researchers made a table of the most and least nutrient-rich foods. For iron and zinc, they also considered their bioavailability.

In the following table we see the grams and calories needed to provide one-third of the daily requirements of vitamin A, folate, vitamin B12, calcium, iron, and zinc for adults over 25 years of age.

Only 11 calories of liver provide 1/3 daily requirement of vit A, vit B12, folic acid, calcium, iron and zinc. To get the same intake of micronutrients we would need to consume 555 calories of legumes. This is nutritional density: the concentration of nutrients within a food. Consuming foods with low nutritional density will inevitably lead us to consume more calories, as proven by the protein leverage hypothesis. Read the in-depth discussion on this subject here.

Let's look carefully: in the top 10 places there are 9 animal sources and 1 plant source. How come? Because animal proteins are foods rich in highly available nutrients and therefore are optimal for the human species. They also contain all the essential amino acids.

CAUTION: With regard to iron, foods have been classified into three levels of absorption:
20% for ruminant meat
15% for all other foods of animal origin.
10% for all foods of plant origin.
Interesting: the level of absorption depends on the proportion of heme and non-heme iron contained 68% heme iron in the meat of ruminants, including beef
39% of heme iron in the pig
26% of heme iron in chicken, fish and seafood, eggs and dairy products
40% of heme iron in all other meats, including offal

Thus, the amount of heme iron contained determines the level of iron absorption. Heme iron is found only in animal meat. So yes, it is true that vegetables also contain iron, but the absorption level is very low because they do not contain heme iron.

If you are iron deficient, give yourself a gift: eat liver! If liver is not your thing today there are supplements containing freeze-dried grass-fed beef liver. In Europe you can find them at Dense Nutrition e Nordic Kings. And who knows, maybe one day even from Live Better! 😉

EVOLUTION

But how come animal proteins are an optimal source of nutrition for the human species? Simple: they are the main food consumed during our evolution. This is not an assumption, it is a certain fact that emerges from analyses of the nitrogen content of our ancestors“ bones. Let me explain: plants absorb nitrogen from the soil and the atmosphere, this nitrogen then ”concentrates“ in herbivores that consume plants and later ”concentrates" in carnivores that consume herbivores. Basically, the percentage of nitrogen in a living thing allows us to understand what it feeds on , and thus where it ranks in the food chain. The bones of our ancestors have a very high nitrogen content, which places them at the top of the food chain. Find all the supporting studies in this in-depth study.

Elena but Paleolithic men died young!

This is not quite so. Life expectancy is simply a statistical calculation that is heavily influenced by infant mortality. It has nothing to do with the age at which people actually died. Let's take an example: during the Roman Empire the life expectancy for a man was 38.8 years. This does not mean most of the population died between the ages of 36 and 40. Emperor Augustus died at age 75, and he was not the only one to die at that age. But then why was life expectancy in the Roman Empire 38.8 years? In the past, infant mortality was very high; this had a huge impact on life expectancy. Let's take an example: imagine a population of 2 people, one dies at 1 year old and the other dies at 79 years old. The sum of years lived is 80, the number of people alive 2, so 80:2 = life expectancy 40 years. Do you realize how misleading this number can be??! Find references to studies on this in the in-depth study cited just above.

Paleolithic humans were nomadic, so they had no real homes that could protect them from the weather; they had no medicines, so infections could easily lead to death; they did not know what hygiene was, so for example, childbirth-related deaths were very high. So it is difficult to compare their length of life with ours (full of comforts and comforts).
However, we can compare physical conditions: they were physically MUCH stronger and healthier than we are. In fact AFTER the introduction of agriculture these facts occurred (18,19):

-We have become shorter.
- - Dental caries increased 4-fold
- - Skull base height decreased de 15%, a sign of malnutrition
- - Pelvic opening index decreased by 7%, an indicator of malnutrition
- - Life expectancy initially worsened, then improved around 2,000 BCE.
- - Iron deficiency anemia has increased
- - Bone density has decreased

Why has our health deteriorated so much since we invented agriculture? Because our diet had dramatically changed: we ate mainly grains and very little meat. Grains are rich in phytates that bind to mineral salts, preventing their absorption (this explains the problems seen above related to bones) also less meat means less highly bioavailable micronutrients (such as iron for example) which then leads to a weakening of the whole body.

Last fascinating thought: when we were primates we ate vegetables, but it seems that what allowed us to grow our brains and become humans was meat. The Expensive Tissue Hypothesis (20) argues that if the brain is large, the gut must be small since both tissues are energetically expensive and it is not sustainable to have both large. Since meat is a food rich in energy and macro- and micronutrients, a smaller gut is sufficient to digest it. This hypothesis holds that when we started eating meat, our intestines shrank and our brains grew.

Today some speculate that the process began 3.4 million years ago when early hominids began eating marrow and brain from the carcasses of animals killed by predators (21). Marrow and brains are highly nutritious and provide the fatty acid precursors needed for brain development. The reason why the pH of our stomach is very acidic (1.5 to 2.0), like that of carcass-eating animals (such as vultures), seems to be just that: we started eating animal protein by feeding on the remains left by carnivores and thus already partially decomposing. The acidity of our stomachs allowed the meat to be disinfected. (22)

MEAT AND LIFE EXPECTANCY

In this interesting study (22) researchers related total meat consumption and life expectancy of 90% of the world population. Their conclusions: “This study showed that meat consumption is positively associated with life expectancy nationwide. The underlying reasons could be that meat provides not only energy but also complete nutrients to the human body. From an evolutionary perspective, meat has probably been an indispensable component of the human diet for millions of years, as evidenced genetically by meat's digestive enzymes and the anatomy of the digestive tract. The comprehensive nutritional profile of meat has enabled humans to achieve many physical benefits, including increased life expectancy.”

NOW LET'S TRY TO USE COMMON SENSE

How is it possible that the absolute richest food in nutrients needed by our bodies, and which allowed us to evolve our brains into humans, is now the cause of colorectal cancer? I leave the answer to you.

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