It should be noted that in recent years meat, especially red meat has been blaming for causing many common diseases of man, including heart diseases, colon and prostate cancer. Everywhere warnings are heard “Do not eat red meat, replace it with vegetable proteins!” Is it really so dangerous or we are witnessing yet another story of human irrationality? I mean a story with eggs when this superfood was tagged with the sign “DANGEROUS” just because of misinterpretations of the study results, and the shelves of our stores have been overloaded with all kinds of cereals.
Here I’ll try to clarify the situation around meat and answer the common questions like: “Does meat cause prostate cancer?”, “What kind of meat can cause prostate cancer and why?”
Meat-an ancient food of man.
Human is an omnivorous species, and meat has been an essential part of his diet for millions of years, and no one doubts it. From the other hand, for the last hundred or so years, humanity has been facing an explosion of modern lifestyle or technology born diseases such as heart diseases, various types of cancer and so on. Does it make sense to accuse in these disasters the best food that has been providing a man with energy and health during his whole life? Probably, instead of criticizing meat and trying to exclude it from our diet we need more carefully analyze the way we feed our animals, the way we process meat, and the way we eat it. How it came that the best food turned out an enemy?
What is meat?
Here are some facts about meat, its nutritious value, and digestibility in comparison to plant foods.
Red meat includes beef, pork, lamb, goat and some parts of poultry. White meat includes breasts of chickens and turkeys. Red meat richer with nutrients than white meat; it contains more fat, and more minerals and vitamins. And what is interesting, all kinds of meats, including fish, red and white meat, contain almost the same amount of cholesterol and there are more and more studies disproving that dietary meat, fat, and cholesterol cause heart diseases.
Meat contains all the nutrients needed for our body in the best-balanced form and proportions. Our digestive system has been evolved mostly to digest animal food rather than plant food. The digestive juices break down all the meat we consume, and we do not need any bacterial help as in the case of plant food, often resulting in unpleasant side effects such as abdominal distention and gas formation.
From 20 amino acids-building blocks of proteins- we can make inside our body only 11, and the remaining 9, called essential amino acids, must be consumed with food. Both animal and plant food contain all 20 amino acids but in varying proportions. Meat contains all essential amino acids, what makes it high-quality protein, while plant foods often contain “incomplete” proteins. Moreover, plant proteins are harder to digest and are absorbed more slowly.
Bioavailability of most vitamins and minerals in meat is much higher than in plant sources. Only from animal food, we get vitamins B12, K2, D3, Docosahexaenoic Acid, Creatine, and Taurine.
Digestibility refers to the proportion of food that becomes available to absorb in our body as nutrients: amino acids (proteins), triglycerides and cholesterol (fats) and carbs (sugars), water, vitamins, and minerals. According to the “Mayo Clinic,” it takes up to 24-72 hours to digest red meat depending on the condition of the person’s health.
Evidence-based studies: does meat cause prostate cancer?
As I showed in the post “What does cause the development of prostate cancer in men?”, the only criteria that should be taken into account in evaluating food risks of triggering the malignant growth of the prostate gland must be its carcinogenic potential.
Heterocyclic amines (HCAs) are carcinogenic compounds found in meats cooked at high temperatures. Chicken is the principal source of HCAs in the United States diet. Five most common HCAs (IQ, MeIQ, MeIQx, DiMeIQx, and PhIP) were tested in the chicken skinless breasts, cooked by different methods: pan-fried, oven-broiled, or grilled/barbecued to three degrees of doneness: just until done, well done, or very well done. Whole chickens also were roasted or stewed. High levels of PhIP (from 12 to 480 ng/g cooked meat) were found in the breasts regardless of cooking method, and its concentration increased with the doneness of the meat. However, PhIP was not detected in the whole roasted and stewed chicken. So some cooking ways produce PhIP, a known carcinogen of colon and breast cancers in rodents and probably in human too. The found levels of PhIP in the chicken were much higher than what has been reported previously in red meat.
Post-diagnostic consumption of chicken with the skin has been reported to increase the risk of cancer progression by 2.26 times. According to the National Cancer Institute, the mutagenicity of broiled, well-done chicken, cooked and consumed with skin is as 3-folds as it is prepared the same way, but the skin is discarded.
In another study association of unprocessed and processed red meat, poultry, and eggs consumption and risk of lethal prostate cancer in presumably healthy and post-diagnostic men were examined. 27, 607 men were followed from 1994 to 2008.
A significant positive correlation was found only between the intake of eggs and risk of lethal prostate cancer. Consumption of 2.5 or more eggs per week was suspected to result in 81% higher risk of lethal prostate cancer compared with consumption of less than half an egg per week. However, opposite results had been obtained in two other studies earlier: 1. No difference in prostate cancer death was found between 7 and less than one egg/week eaters. 2. A 20 g increase in egg consumption per day resulted in a decrease in the risk of advanced prostate cancer by 30% in the Netherlands study.
Contrary to expectations, unprocessed red meat showed an inverse association, whereas poultry and processed red meat showed no correlation with the risk of lethal prostate cancer. They also did not find any relation between intake of total red meat (unprocessed or processed), whole poultry, and eggs after diagnosis and the risk of progression to lethal prostate cancer.
A combined analysis of prospective studies (up to 2010) on red and processed meat intake and prostate cancer reported no correlation between them. If any association exists here, it must be negligible.
What do we buy in the store together with meat?
Pesticides in the meat that do cause prostate cancer.
The majority of the US population shows measurable levels of various pesticides in their urine, as has been reported by the National Health and Nutrition Survey. While pesticides are widely used in agricultural, commercial and residential environments, intake of the food treated with pesticides is the principal route of human poisoning.
Any pesticides broadly used in our surroundings exert adverse dose-dependent toxic effects in animals as well as humans. They say “the majority of pesticides currently registered for use in the United States, are neither overtly genotoxic nor carcinogenic in rodent studies.” STOP! WAIT TO UPLOAD! Who followed up the possible adverse effects of low doses of these chemicals for 30-50 years, the time supposedly needed to destroy our body and cell defense systems ultimately? Does it make sense to transfer the results of studies conducted on rodents, which live for two years at best, to humans who live 50 times longer? Probably we, humans, not rodents, are the subjects of someone’s experiments. Sounds unbelievable, but let’s analyze just only a few of them from a list of pesticides, for which post-market examination confirmed prostate carcinogenicity:
- DDT- Insecticide
- Chlordecone- Insecticide
- Fonofos- Insecticide
- Lindane- Herbicide
- Simazine- Herbicide
- Butylate- Herbicide
DDT Insecticide Organochlorine. From 1945 until 1972 when it was banned, DDT was available for public sale in the United States. It has been estimated that a total of 1.8 million tonnes of DDT have been produced globally since the 1940s. In the soil, DDT may preserve its properties up to 60 years. Therefore, it is not surprising that it was detected in almost all human blood samples tested by the Centers for Disease Control in 2005. DDT is toxic to virtually all types of animals, including human, but in the wildlife, the most vulnerable species turned out prey-birds due to the accumulation effect of DDT in the food chain. No wonder, that the national bird of the United States bald eagle and the peregrine falcon being at the near-extinction have been recovered following DDT ban.
As an endocrine disruptor, DDT may cause spontaneous abortions,
preterm birth, disruption in semen quality, menstruation, gestational length, and duration of lactation, impaired thyroid function in pregnancy and childhood.
A significant correlation between prostate cancer risk and exposure to DDT, Simazine, and Lindane was found among 1,516 prostate cancer cases in British Columbia, Canada.
In 2015, the International Agency for Research on Cancer classified DDT as Group 2A “probably carcinogenic to humans.”
Chlordecone Insecticide Cyclodiene. Chlordecone is another estrogenic insecticide that has been used widely in the world for more than 30 years. It is now forbidden in the western world, as well as in the US, but only after many thousands of tonnes had been produced. In a study of 709 prostate cancer cases between 2004 and 2007 in Guadeloupe, prostate cancer risk rose with increasing plasma Chlordecone concentration. This substance binds the estrogen receptor which is in charge of the adverse effects of estrogen on the prostate, such as inflammation, aberrant proliferation, and malignancy, providing additional support for the hypothesis that estrogens increase the risk of prostate cancer.
Hundreds of studies convincingly show that prostate cancer is associated with pesticide use. These chemicals are stable substances and save their toxicity for tens of years in our soils, being available for the next generations. From the soil, the pesticides get into the crops, from the crops -into the animals and from animals -into humans, at each stage accumulating at more and more concentrations. Check any substance from the list above, and you will find how meat from the delicacy and healthy food can be transformed into the source of harm to our body.
Hormones in the red meat may increase your risk of prostate cancer.
We have all heard that red meat and dairy products produced in the United States are contaminated with natural sex hormones: estrogen, progesterone, and testosterone, as well as synthetic sex hormones: zeranol, trenbolone, and melengesterol. Steroids allow to gain 10% more milk and increased carcass weight, adding an extra profit of $80 per animal.
But what do Americans pay the price for this extra profit?
Increased level of reproductive cancers in the United States since 1975: 60% for prostate, 59% for testis, 10% for breast and 38% for childhood cancer.
Risk of breast cancer in American women is as 5 -fold as women in countries that banned hormones in animal feed.
The European Commission, Canada, Australia, New Zealand, and Israel set a ban on both the production and importation of meat obtained from animals treated with hormones as early as the 1980s.
Dr. Samuel S. Epstein, Chairman of the Cancer Prevention Coalition, says “Not surprisingly, but contrary to longstanding claims by the U.S. Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA), residues of these hormones in meat are up to 20-fold higher than normal.”
Moreover, there is a large group of synthetic and natural chemical compounds, xenoestrogens, that imitate estrogenic activity. As a result of environmental pollution with estrogens, global deterioration of male reproductive function and progressive feminization of the animal world, including human has been taking place.
Processed meat can increase your risk of prostate cancer.
Processed meat includes ham, bacon and other cured or preserved meats. Regarding the consumption of unprocessed and processed meat, there has always been a dispute between two opposing points of view. It is easily understandable, the lobby of meat producers as well as meat lovers is quite strong in countries with developed economies.
Nevertheless, in 2015 the World Health Organization (WHO) ranked processed meat to Group I carcinogens (the same group as cigarettes) and red meat – to Group 2A, probably carcinogenic to humans. This was the final decision of the International Agency for Research on Cancer comprised of 22 scientists from 10 countries after evaluation of over 800 studies. Conclusions were principally based on the evidence for colorectal cancer as well as stomach, pancreatic and prostate cancers.
In 2017 American Institute for Cancer Research found that every 50 grams of processed meat eaten daily — about one hot dog — increases the risk of colon cancer by 16%. There was substantial evidence that physical activity protects against colon cancer.
Even though the recommendations of WHO to limit or eliminate consumption of red and processed meat are based on data from epidemiological studies which always have certain confusing limitations and on the animal studies, as they say, “No smoke without fire.”
Moreover, processed meat, mainly red meat contains chemicals that have been found to produce tumors in animals.
Charring and wood-smoking of meat results in the formation of polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs) which have been shown to induce cancer in lab animals.
Meat processing such as curing by adding nitrates and nitrites and salt leads to the formation of potentially carcinogenic substances such as N-nitroso-compounds (NOCs). Red meat, unlike white meat, also contains heme iron, which can facilitate the production of NOCs. Nitrates and nitrites need to react with the proteins of meat to create NOCs. This reaction can be nocked down by adding special antioxidants, but it doesn’t stop NOCs formation entirely. Therefore, choose fresh beef when possible.
Meat diet may promote gut bacteria producing carcinogenic substances.
There is not much evidence of a relation of gut bacteria metabolism and prostate cancer in the literature. However, multiple studies suggest gut flora to affect the incidence of colorectal cancer and that there is a linear association between prostate cancer and colorectal cancers.
Bacteria live in the gut system of any animal species, from insects to humans. If in the stomach and small intestine, only a few bacteria species have been found, the colon is densely populated with more than 500 different species. Bacteria make up to 60% of the dry mass of feces.
Sulfate reduction. Sulfate-reducing bacteria (SRB) as a part of the normal gut flora, contribute to the immune response stimulation in the gut, but when their number increases enormously, they may contribute to colitis development mediated with hydrogen sulfide (H2S) production. Hydrogen sulfide is a hazardous gas with a “rotten egg” smell. It can be produced by the decay of human and animal organic wastes. Hydrogen sulfide has a potential to damage genomic DNA, causing genotoxic effects in the gut cells. Meat proteins are rich in sulfur-containing amino acids, and meat diet may result in SRB abundance and therefore contribute to H2S formation increasing the risk of colorectal cancers.
Nitrate reduction. Some species of bacteria in the gut can reduce nitrates to nitrites via nitrate reductase. The subsequent interaction of nitrites with organic substances results in the production of NOCs-carcinogens, mentioned earlier. Red and processed meat, rich in protein and other nitrogenous residues, may support increased production of NOCs by gut bacteria. The more you eat meat, the more nitrogenous residues get into your colon. Nitrosamines, nitrosamides, and nitrosoguanidine are classes of NOCs found in feces. NOCs can form DNA adducts- segments of DNA bound to a cancer-causing chemical, which induce mutations.
Unlike red and processed meat, which contain heme iron in abundance, and produce increased fecal NOCs, white meat and vegetable protein did not increase fecal NOCs. Heme iron is an essential part of hemoglobin, the red pigment in blood, and myoglobin the principal oxygen-carrying pigment of muscles. High levels of myoglobin in muscles allow diving animals such as whales, holding their breath for a more extended period. So, heme iron, a specific part of red meat, can catalyze NOCs formation and may be responsible for the additional dose-dependent N-nitrosation in the gut. Addition of soy may significantly suppress fecal NOCs.
So even if we consume pesticide-free, fresh meat cooked by the most gentle way, we still have a chance to increase the odds of prostate cancer due to abnormal metabolism of our gut flora. But does it mean that we should eliminate meat from our diet? Definitely, no. Instead of giving men recommendations to give up the best food that allows them to feel male, we need more intensively study the lifestyle conditions which would enable avoiding any adverse consequences of eating meat.
Pesticides, sex hormones, chemicals found in processed meat (PAHs, HCAs, and NOCs) are all substances, getting into the meat from outside our body. We can minimize their harmful effects by choosing the right meat producer, the way of processing or cooking meat. Hydrogen sulfide and NOCs produced by the gut flora, we can control by taking care of digestive system health and appropriate lifestyle.
Read more about a new hypothesis, how do gut bacteria may promote prostate cancer, and how to minimize the risks, in the next post.
So, it is evident that the technological revolution and science development that has been taking place for the last 100 years, discovered new, unseen before, opportunities in agriculture. However, an introduction of any “innovations” in agriculture intruding the natural course of events have two sides of a coin. The explosion of heart diseases, various types of cancer and lots of other disorders of humans and animals are only visible outcomes of this process. And what is interesting, our lifestyle has been changed; accordingly, we got more sedentary, obese, anxious and stressed. Now that awareness has come, it is up to us, to abandon meat and other products that we have eaten for ages for the sake of a new lifestyle, or to feed our body the best food it needs and change our lifestyle to get the most from it.
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- Rashmi S. et al., High Concentrations of the Carcinogen 2-Amino-1-methyl-6-phenylimidazo-[4,5-b]pyridine (PhIP)
Occurin Chicken but Are Dependent on the Cooking Method. Cancer Res. 1995 Oct 15;55(20):4516-9.
- Erin L. R et al., Egg, Red Meat, and Poultry Intake and Risk of Lethal Prostate Cancer in the Prostate-Specific Antigen-Era: Incidence and Survival. Cancer Prev Res; 4(12); 2110–21. ©2011 AACR.
- National Cancer Institute. CHARRED: Computerized heterocyclic amines resource for research in
epidemiologyof disease. 2006.
- Alexander DD, et al. A review and meta-analysis of prospective studies of red and processed meat intake and prostate cancer. Nutr J 2010;9:50.
- Schuurman AG, van den Brandt PA, Dorant E, Goldbohm RA. Animal products, calcium and protein
andprostate cancer risk in The Netherlands Cohort Study. Br J Cancer 1999;80:1107–13.
- Alavanja MC, Bonner MR. Occupational pesticide exposures and cancer risk: a review. J Toxicol Environ Health B Crit Rev. 2012;15(4):238-63.
- Meredith A. J. et al. Gut Microbes, Diet, and Cancer. Cancer Treat Res. 2014; 159: 377–399.