Relationship between eating meat and cancer

Meat, fish, dairy & cancer | World Cancer Research Fund International

relationship between eating meat and cancer

Eating 50 grams of processed meat daily also increases the risk of prostate . Processed meats cause colorectal cancer, and rates are rising among young. World Health Organization stated that eating meat causes cancer that analyzed the relationship between the consumption of red meat (or. Eating a lot of red and processed meat probably raises your risk of bowel cancer. looked at studies that assessed the link between iron and bowel cancer.

Our major findings on cancer and animal foods There is strong evidence that consuming: Cancer Prevention Recommendation Eat no more than moderate amounts of red meat, such as beef, pork and lamb.

WHO Says Meat Causes Cancer? - Diagnosis:Diet

The Panel did not base a recommendation on the strong evidence that the consumption of dairy products decreases the risk of colorectal cancer as there is some other evidence that is suggestive of an increased risk of prostate cancer, although that evidence fell below the general threshold required for making a recommendation.

For more information on when the evidence is divergent between cancer sites, download the chapter of the Third Expert Report on Recommendations. Mechanisms This section covers the primary hypotheses and is not based on a systematic or exhaustive search of the literature. Red meat and cancer Cooking meats at high temperatures, prolonged exposure to heat and cooking by various types of grilling results in the formation of heterocyclic amines and polycyclic aromatic hydrocarbons both of which have been linked to colorectal cancer development in experimental studies.

In addition, haem iron, which is present at high levels in red meat, has been shown to promote colorectal tumorigenesis by stimulating the endogenous formation of carcinogenic N-nitroso compound.

Polycyclic aromatic hydrocarbons, which are formed when organic substances like meat are burnt incompletely, may also have carcinogenic potential.

Grilling broiling and barbecuing charbroiling meat, fish, or other foods with intense heat over a direct flame results in fat dropping on the hot fire, causing flames; these flames contain polycyclic aromatic hydrocarbons that stick to the surface of food.

Processed meat and cancer Overall it is likely that a combination of mechanisms contribute to higher risk of colorectal cancer among people consuming high quantities of processed meat. Processed meat is invariably higher in fat content than red meat which may promote carcinogenesis through synthesis of secondary bile acids; however, human data supporting this hypothesis are weak.

Processed meat is also a source of exogenously derived N-nitroso compounds, which may have carcinogenic potential. 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. And I am not alone.

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. The role of red and processed meat in colorectal cancer development: To read the full report: Now THAT is a responsible, honest, scientific conclusion.

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: 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.

relationship between eating meat and cancer

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. 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.

relationship between eating meat and cancer

Yes, you read that correctly. All were conducted with a very small number of subjects and were seriously flawed in more than one important way.

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. 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 Databaseraw 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.

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. 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.

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

The WHO considered over epidemiological studies regarding red and processed meat and cancer. They based their findings on 56 studies relating to colorectal cancer.

relationship between eating meat and cancer

Of the red meat studies, more than half found no link between red meat and cancer. 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 guessesand 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. You interview 10, alcoholics and 10, 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: 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.

Feed some non-alcoholics pretzels every day and watch what happens to them compared to a similar group who is banned from eating pretzels.

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Klurfeld DM Research gaps in evaluating the relationship of meat and health. 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: Among the 12 rodent studies reported in the literature, none demonstrated a specific promotional effect of red meat. Beef meat and blood sausage promote the formation of azoxymethane-induced mucin-depleted foci and aberrant crypt foci in rat colons. 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.

relationship between eating meat and cancer

This is why our nutrition headlines are constantly changing. 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.

Red meat in rats Reference Pierre FH et al 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: Inject rats with azoxymethane, a powerful carcinogen. All rats, including the chicken-fed rats, developed potentially pre-cancerous changes in the colon.

Meat, dairy, and cancer

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.

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.

Beef meat promotion of dimethylhydrazine-induced colorectal carcinogenesis biomarkers is suppressed by dietary calcium. Br J Nutr Adequate dietary calcium prevents your colon from looking funny if you find yourself in the unfortunate circumstances described in Reference The WHO offers three possible theories about how processed meat could cause cancer: 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.

Processed Meat Probably Causes Cancer (According to the World Health Organization)

Problem with theory 1: 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: Problems with theory 2: Also, the doses of these compounds that cause cancer in animals are 1, totimes 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. Processed meat in rats 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 type of packaging? The researchers compared a variety of pork processing methods: 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 F, and left unwrapped in the refrigerator for 5 days.