August 10th, 2017|Nutrition|
Red Meat and Cancer - Myolean Fitness

Guest author: Vincent Sparagna (For questions, email at Vincentsparagna@gmail.com)

Reviewed by: Antonis Damianou (myoleanfitness.com), Alex Leaf (leaf-nutrition.com/examine.com), and Sérgio Fontinhas (Big Fitness Project)

The start of the controversy about red meat and cancer

In October 2015, the World Health Organization (WHO) released a report stating that eating processed red meat causes cancer and eating unprocessed red meat probably causes cancer (3,179,193).

Is there, however, an actual cause and effect relationship between the consumption of red meat and cancer?

What are the mechanisms through which red meat may causes cancer?

Is there anything we can do to reduce the potential cancer risk from red meat consumption without completely giving up red meat?

These are some of the questions answered in this article.

But first, here are some of the key takeaways.

Key takeaways

  • Given an otherwise healthy overall lifestyle, moderate red meat consumption is likely fine.
  • Red meat’s dose makes the poison, so it’s wise to moderate red meat intake (particularly, processed red meat).
  • Red meat consumption correlates positively with cancer (mainly colorectal cancer). While consuming red meat may cause cancer, research cannot establish causation, given numerous confounders and lack of intervention studies.
  • Processed red meat and cancer correlate better than unprocessed red meat and cancer.
  • Some authorities recommend consuming “no more than one to two servings per month of processed meats, and no more than one to two servings per week of unprocessed meat” (1); others suggest <300 grams (~10.58 ounces) of red and processed meat per week (187). The World Cancer Research Fund recommends consuming <500 grams (~17.64 ounces) of red meat per week, with very little to no processed red meat (197). There is not sufficient evidence to conclude a definitively safe intake level.
  • Red meat consumption may be carcinogenic through various mechanisms, but your actions can mitigate these risks.
  • Red meat’s link to cancer is pragmatically relevant because you control how much red meat you consume. However, red meat consumption is certainly not the primary factor influencing cancer risk (2).
  • Red meat consumption yields some health benefits, so despite its link to cancer, occasional red meat consumption may improve health.

What type of cancer?

Cancer encompasses a broad number of diseases rather than one uniform condition.

Colorectal cancer (cancer of the colon or rectum) is the third leading cause of cancer-related death in both the United States and world (41,192). Red meat consumption correlates most meaningfully with colorectal cancer.

Less convincing evidence positively correlates red meat consumption with breast, pancreatic, lung, esophageal, gastric, liver, stomach, bladder, head-and-neck, and prostate cancer, as well as non-Hodgkin lymphoma and multiple myeloma (3-40, 45,176,177,187-190,193,197-204,207).

Differentiating between red meats

According to the WHO, “Red meat refers to all mammalian muscle meat, including, beef, veal, pork, lamb, mutton, horse, and goat.” (43).

“Processed meat refers to meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavour or improve preservation.” (43).

The primary difference is that processed red meat undergoes further processing than red meat.

Red meat and cancer risk classifications

The WHO classifies processed red meat as a group 1 carcinogen and classifies red meat as a group 2A carcinogen (43,179,181,191).

A group 1 carcinogen is defined as “carcinogenic to humans” while a group 2A carcinogen “probably” causes cancer (43,179,181,191).

Red meat and cancer risk - Cancer Risk Classifications - IARC - Myolean Fitness

Adapted from: IARC (179)

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It is important to note that, for group 1 classifications, the International Agency for Research on Cancer (IARC) states that,

“an agent may be placed in this category when evidence of carcinogenicity in humans is less than sufficient but there is sufficient evidence of carcinogenicity in experimental animals and strong evidence in exposed humans that the agent acts through a relevant mechanism of carcinogenicity.” (215).

Moreover, for group 2A classifications, the IARC states that,

“an agent may be classified in this category when there is inadequate evidence of carcinogenicity in humans and sufficient evidence of carcinogenicity in experimental animals and strong evidence that the carcinogenesis is mediated by a mechanism that also operates in humans. Exceptionally, an agent may be classified in this category solely on the basis of limited evidence of carcinogenicity in humans.” (215).

How carcinogenic is red meat?

In a 2017 narrative review, Wolk concluded that consuming 100 grams (~3.53 ounces) of unprocessed red meat per day correlates with increased risk for breast cancer (11%), colorectal cancer (17%), and advanced prostate cancer (19%) (194). Wolk also reported that consuming 50 grams (~1.76 ounces) of processed red meat per day correlates with increased risk of advanced prostate cancer (4%), cancer mortality (8%), breast cancer (9%), colorectal cancer (18%), and pancreatic cancer (19%) (194).

Another meta-analysis from December 2017 reports similar findings to Wolk concerning colorectal cancer (228). This analysis (of 25 studies) discovered a linear dose-response relationship between both processed and unprocessed meat and colorectal cancer risk. Consuming 100 grams of unprocessed red meat per day correlated with a 1.12 relative risk, while consumption of 50 grams of processed meat per day correlated with a 1.17 relative risk (228). Consuming 4 servings of red meat per day or 2 servings of processed meat per day correlated with 1.8-fold colorectal cancer risk. This review also reported that low red meat consumption, paired with a high whole grain, vegetable, fruit, and dairy product consumption, correlated with decreased colorectal cancer risk (228).

Further, Grundy et al (2012) reported that red and processed red meat consumption caused roughly 12% of colorectal cancers in Alberta, Canada (1.5% of all cancers) (195). Of note, roughly 1 in 2 men and 1 in 4 of the study’s women exceeded the World Cancer Research Fund’s 500 gram (~17.64 ounces) red and processed meat per week recommendation (195,190).

Wang et al’s (2016) meta-analysis (of 17 prospective cohorts) found that more red and processed meat consumption correlated with increased total, cardiovascular, and cancer mortality risk (202).

The WHO’s report concluded that by not consuming red meat, one’s colorectal cancer risk may decrease by ~18% (3,179). However, it’s very difficult to quantify the correlated risk increase, as meat is one variable in our multifactorial diet. Further, it’s impossible to quantify the exact percentage risk increase, given confounders (e.g. sleep and stress).

Lifestyle factors confounding red meat-consumption-induced colorectal cancer risk include regular smoking, high BMI, and alcohol consumption (6,5,7,9,17,23,25,26,28,35,44-50,190,198,199,212).

Additionally, greater fruit and vegetable consumption correlates with generally reduced cancer risk, confounds red meat’s effects considerably (7,10,11,21,33,36,42,44,51-58,178,198,212). We cannot quantify the degree to which fruit/vegetable consumption (or lack thereof) influences cancer risk in red meat-related trials.

We cannot determine red meat’s carcinogenicity, as observational research lacks the control needed to establish this link (50,59-61). Since many factors alter cancer risk, and cancer takes years to develop, cancer-related randomized trials are difficult to conduct.

Red Meat and Cancer Risk - Risk by cancer type with processed meat Graph - Myolean Fitness

Note: All baseline values are derived from the Cancer Statistics Center website.

Baseline cancer risk and absolute risk with red meat consumption

The above graph represents the percentage cancer risk change correlated with consuming ~50 grams (~1.76 ounces) of processed red meat or ~100 grams (~3.53 ounces) of unprocessed red meat per day (except for ovarian, which is ~50-100 grams/week).

For example, the relative risk (risk compared to baseline; expressed as a decimal) for both unprocessed and processed red meat is 1.08 for bladder cancer. As such, compared to baseline (1.0), bladder cancer risk increases by 8% upon consuming ~100 grams of red meat or ~50 grams of processed red meat per day. This doesn’t mean that one’s absolute cancer risk increases by 8%; this means cancer risk increases by 8% of the 2.4% baseline bladder cancer risk. The initial 2.4% absolute risk thus increases by .192% (from 2.4% to 2.592%).

Despite an evident relative risk increase, absolute cancer risk doesn’t increase substantially after consuming 100 grams (~3.53 ounces) of red meat or 50 grams (~1.76 ounces) of processed red meat.

Mechanisms through which red meat may increase cancer risk

In a 2017 paper, Johnson reported several identified mechanisms for meat consumption’s mutagenic effects. Unfortunately, it’s not clear which mechanisms cause cancer in humans. Additionally, the extent to which avoiding red meat decreases cancer risk is unknown (204).

Mechanism 1: NOCs

Processed red meat contains N-nitroso compounds (NOCs). NOCs form endogenously from nitrite and nitrate intake (223).

Upon red meat consumption, heme iron catalyzes N-nitroso compound formation, in a dose-dependent manner (46,63-65,67,74,76,77,131,192). These N-nitroso compounds can potentially damage the gut lining, initiating cell regeneration, which may eventually damage DNA (14,63,78-82,205).

Unprocessed red meat effects gut damage less directly than processed red meat (after curing and smoking). This occurs because processed red meat’s chemicals potentiate faster NOC formation (69,181,192).

What you can do about it: The gut damage caused by NOCs can be reduced or eliminated if the meat is consumed with green vegetables (64). This is because green vegetables contain chlorophyll and/or vitamin C, which may prevent NOC formation (83,54-56). Other high-vitamin C foods should decrease damage as well, though limiting or abstaining from red or processed red meat consumption may help more.

Mechanism 2: High-Heat Chemicals

Heterocyclic amines (HCAs) and Polyaromatic Hydrocarbons (PAHs) form when meat is cooked at high heat or smoked (less so with white meat) (75,93,100-111,181). These heat compounds can damage the gut, and the International Agency for Research on Cancer considers them potentially carcinogenic (98,113,114). Re-heating meat does not seem to contribute to heat compound content (112).

Several genetic mutations (e.g. those involving enzymes NAT1 and NAT2), given their role in HCA metabolism, correlate with increased cancer risk (118-122).

Some researchers suggest that high-heat compounds cannot completely explain the link between colorectal cancer and red/processed meat intake (192). For example, Van Hecke suggests that NOCs and oxidation products better explain red/processed meat’s correlation with colorectal cancer risk (210).

Few studies find significant associations between white meat (e.g. poultry or fish) consumption and cancer (181,189,187,213). Since cooking white meat also creates high-heat chemicals, high-heat chemical concentrations alone, cannot explain (processed) red meat’s carcinogenicity.

Additionally, PAH’s bioaccessibility in meat is under-studied (210), thus its carcinogenic potential is unknown.

However, one may still want to cook red meat at a lower heat. Cooking meat at low heat, reduces advanced glycation end product formation, thereby potentially improving insulin resistance in the obese (224).

What you can do about it: Eating meat with cruciferous vegetables (such as broccoli or Brussels sprouts) or marinating the meat in spices (especially Caribbean spices, such as allspice berries) for 20+ minutes before cooking can reduce HCA and PAH formation; preventing much of the heat-chemical induced damage (115,11,51-53,179).

One could also simply cook the meat at a lower heat and/or not cook over an open flame (38,43,93,96,101,109,113,114,116,117,209).

Mechanism 3: Iron

Red meat contains abundant iron, which intestinal tract cells oxidize easily, as other compounds don’t bind tightly to iron (64,125,126). Iron oxidation can cause cell damage, and this might explain the link to increased risk of colorectal cancer (127-130).

Heme iron seems to catalyze NOC formation, thus may thereby contribute to cancer risk further (46,63-65,67,74,76,77,131,192,205).

Allison-Sliva highlights that this mechanism isn’t universally relevant to cancer. This is because cooking denatures heme, which creates high plasma hemopexin levels that block its tissue delivery. As such, red meat-derived heme can only contribute to colorectal carcinoma risk, via local effects (208).

What you can do about it: There is no way to mitigate the effect of excess iron from red meat without simply consuming less red meat.

Mechanism 4: TMAO

Trimethylamine N-oxide (TMAO) is a controversial compound that research has linked to colon and colorectal cancer (132,219).

Red meat is high in choline and L-carnitine (amino acid), which gut bacteria may metabolize into TMAO (133,134,194,216,217,218). High TMAO levels correlate with high TMA and DMA levels (216). TMA and DMA risk undergoing nitrosation, which potentially causes cancer (via nitrosated amine formation) (218).

However, TMAO may be a lurking variable, rather than a mechanism causing red meat’s carcinogenicity (218). Evidence of TMAO’s protective effect in carcinogenesis (by correcting mutant protein folding (218,220,221)) supports this assertion.

What you can do about it: The effects that TMAO has on gut health are still largely unknown, though maintaining a healthy gut (by eating a diet rich in fruits and vegetables) can prevent some potential damage from red meat (44,135,7,10,11,21,33,36,42,44,51-58,178,191).

Mechanism 5: Neu5Gc

Human blood contains N-Acetylneuraminic acid (Neu5Ac), but nearly every other mammal’s blood has N-glycolylneuraminic acid (Neu5Gc) type sugars.

Because Neu5Gc and Neu5Ac differ, red-meat derived Neu5Gc ingestion may trigger an immune response, potentiating inflammation and carcinogenesis (137,208).

Human tumors contain high Neu5Gc levels, and Neu5Gc seems carcinogenic to mice. However, we don’t know the dose at which Neu5Gc proves toxic (136,137,222).

What you can do about it: The only way to mitigate the effects of Neu5Gc is to eat less red meat.

Mechanism 6: Environmental Pollutants

Potentially carcinogenic environmental pollutants include: heavy metals, polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (PCBs), and other persistent organic contaminants (181).

The content of these pollutants differs depending on the processing or cooking method of the meat (181).

Non-red meats typically contain fewer organic compounds, so red meat’s baseline carcinogenic potential is higher (181).

In a 2017 review, Domingo and Nadal outline that certain cooking processes modify red meat’s environmental pollutant content (181-186).

What you can do about it:

Environmental pollutants concentrations depend (mostly) on the food’s baseline pollutant contents, rather than the food’s preparation method. Since environmental pollutants are typically organic, fat-releasing cooking procedures should also reduce red meat’s pollutant concentrations (181,185,186).

Online Coaching Side Widget within text 2 - Myolean Fitness

A few important notes on the above mechanisms

Allison-Silva (2016) notes that TMAO, heat compounds, and environmental pollutants are not specific to red meat (208).

Additionally, n-nitroso compounds, heme iron, and heme’s potential to catalyze endogenous nitrosation are specific to red meat. Though, not even these mechanisms explain red meat’s (unique) carcinogenicity to humans, as other carnivores maintain lower risk (208).

Environmental pollutants and infectious agents from dairy cattle may partially explain this discrepancy in risk (208).

Neu5Gc’s metabolic incorporation into red meat consumers’ bodily tissues, followed by inflammation-provoking antibody interactions, potentially explains red-meat induced cancer risk increase (208).

Multiple studies have discovered carcinogenic compounds (e.g. PCDD/Fs, dioxin-like PCBs or PAHs) in raw red meats, which sometimes contain notable carcinogen concentrations (varying with the meat’s type and origin).  Therefore, consuming these meats, processed or not, certainly seems risky. Cooking or processing can only add new carcinogens, or increase concentrations of (e.g. PAHs/HCAs) raw/uncooked meat’s pre-existing carcinogens (181).

Why you may want to consume red meat

Despite processed or unprocessed red meat’s link to cancer, one might still benefit from red meat consumption:

  • Red meat contains essential nutrients iron, zinc, and vitamin B12 (138-140,190,194,196), thus its consumption helps prevent certain nutrient deficiencies. However, people can obtain these nutrients from other, less potentially carcinogenic sources.
  • Protein plays a vital role in muscle growth (especially when paired with resistance training) (141-145,159,163). Red meat is a great source of protein. Additionally, red meat has a high thermic effect (146), is highly satiating (difficult to overeat; blunts hunger) (139,147,148), and thus may improve weight loss or maintenance (139,146-148). However, other protein sources (such as white meat) may yield similar benefit with less potential risk.
  • Red meat is high in (rare) vitamin K2 (150-155), which potentially kills cancer cells through “oncosis” (killing through oxidation) (156), and may prevent cancer cell formation via autophagy (dead cell matter recycling) (157,158). Unfortunately, I doubt vitamin K2’s benefits outweigh the increased cancer risk correlated with red meat consumption. Additionally, few other vitamin K2 sources exist (only other meats, egg yolks, cheeses, or natto (225,226)).
  • Red meat contains creatine, which might reduce depression (164), enhance brain energetics (165-169), increase muscle growth (161-163, 170,171,180), and improve athletic performance (162, 168,170-175). Vegetarians have lower baseline creatine levels than omnivores (161-163), thus meat consumption likely boosts creatine levels. However, one must consume more red meat than recommended to reap creatine’s benefits, thus I recommend creatine monohydrate supplementation instead.
  • Certain populations can benefit from red meat consumption:
    •  Red meat consumption may tremendously benefit the elderly. Since red meat consumption increases muscle growth when paired with resistance training (159), it helps mitigate sarcopenia (age-related muscle loss). It is prudent to prevent sarcopenia because it contributes to weakness, poor health, and physical ineptitude (160,180).
    • Red meat consumption may enhance growth (mid-arm muscle area), cognitive function (arithmetic performance), and behavior (initiative leadership) in Kenyan children (81). As such, red meat consumption may benefit developing children.
    • Iron deficiency is common (214), and red meat is rich in iron (227), thus red meat consumption may benefit anemics. However, many other dietary iron sources exist.

Conclusion

Most scientific literature indicates a link between red meat and cancer, although we cannot conclude causality without intervention studies. Moreover, there are numerous confounders in this research, making red meat’s carcinogenicity difficult to quantify.

We need more research to establish red meat’s most relevant cancer-inducing mechanisms (specifically for colorectal cancer risk).

Red meat consumption is only one determinant of cancer risk. Reduce general cancer risk by avoiding excessive alcohol consumption, stress, smoking, high BMI, and sleep deprivation. Similarly, it’s prudent to consume fruits and vegetables, while exercising often.

Available evidence indicates that red meat consumption likely increases cancer risk, while processed red meat almost certainly does. However, I doubt red meat increases cancer risk meaningfully if you moderate consumption and maintain healthy lifestyle habits.

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  140. https://data.oecd.org/agroutput/meat-consumption.htm
  141. Leucine Regulates Translation Initiation of Protein Synthesis in Skeletal Muscle after Exercise
  142. Nutritional and regulatory roles of leucine in muscle growth and fat reduction.
  143. Amino acids: metabolism, functions, and nutrition
  144. Branched-chain amino acids activate key enzymes in protein synthesis after physical exercise.
  145. Branched chain amino acids activate messenger ribonucleic acid translation regulatory proteins in human skeletal muscle, and glucocorticoids blunt this action.
  146. A high-protein diet for reducing body fat: mechanisms and possible caveats.
  147. The satiating power of protein—a key to obesity prevention?
  148. Protein, weight management, and satiety
  149. Dietary intake of vitamin K and risk of prostate cancer in the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC-Heidelberg)
  150. Vitamin k contents of meat, dairy, and fast food in the u.s. Diet.
  151. Measurement of K vitamins in animal tissues by high-performance liquid chromatography with fluorimetric detection.
  152. Quantitative measurement of tetrahydromenaquinone-9 in cheese fermented by propionibacteria.
  153. Vitamin K content of foods and dietary vitamin K intake in Japanese young women.
  154. Determination of phylloquinone and menaquinones in animal products with fluorescence detection after postcolumn reduction with metallic zinc.
  155. Quantitative measurement of vitamin K2 (menaquinones) in various fermented dairy products using a reliable high-performance liquid chromatography method.
  156. https://en.wikipedia.org/wiki/Ischemic_cell_death
  157. Growth inhibitory effects of vitamin K2 on colon cancer cell lines via different types of cell death including autophagy and apoptosis.
  158. Apoptosis of liver cancer cells by vitamin K2 and enhancement by MEK inhibition.
  159. Protein-enriched diet, with the use of lean red meat, combined with progressive resistance training enhances lean tissue mass and muscle strength and reduces circulating IL-6 concentrations in elderly women: a cluster randomized controlled trial
  160. Sarcopenia: An Undiagnosed Condition in Older Adults. Current Consensus Definition: Prevalence, Etiology, and Consequences
  161. Vegan diets: practical advice for athletes and exercisers
  162. Effect of creatine and weight training on muscle creatine and performance in vegetarians.
  163. Effect of creatine supplementation and a lacto-ovo-vegetarian diet on muscle creatine concentration.
  164. Open-label adjunctive creatine for female adolescents with SSRI-resistant major depressive disorder: a 31-phosphorus magnetic resonance spectroscopy study.
  165. Effect of creatine supplementation and sleep deprivation, with mild exercise, on cognitive and psychomotor performance, mood state, and plasma concentrations of catecholamines and cortisol.
  166. The influence of creatine supplementation on the cognitive functioning of vegetarians and omnivores.
  167. Oral creatine monohydrate supplementation improves brain performance: a double-blind, placebo-controlled, cross-over trial.
  168. Creatine supplementation, sleep deprivation, cortisol, melatonin and behavior.
  169. Prevention of traumatic headache, dizziness and fatigue with creatine administration. A pilot study.
  170. Effects of acute creatine monohydrate supplementation on leucine kinetics and mixed-muscle protein synthesis
  171. Global and targeted gene expression and protein content in skeletal muscle of young men following short-term creatine monohydrate supplementation.
  172. Effect of creatine supplementation on jumping performance in elite volleyball players.
  173. Skill execution and sleep deprivation: effects of acute caffeine or creatine supplementation – a randomized placebo-controlled trial.
  174. Does oral creatine supplementation improve strength? A meta-analysis.
  175. Global and targeted gene expression and protein content in skeletal muscle of young men following short-term creatine monohydrate supplementation.
  176.  Intakes of red meat, processed meat, and meat-mutagens increase lung cancer risk
  177.  A prospective study of red and processed meat intake in relation to cancer risk.
  178. Eat to live, not live to eat.
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  180. Exercise and nutritional interventions for improving aging muscle health.
  181. Carcinogenicity of consumption of red meat and processed meat: A review of scientific news since the IARC decision.
  182. Occurrence of halogenated flame retardants in commercial seafood species available in European markets
  183. Exposure to perfluorinated compounds in Catalonia, Spain, through consumption of various raw and cooked foodstuffs, including packaged food
  184. Effects of various cooking processes on the concentrations of arsenic, cadmium, mercury, and lead in foods.
  185. Concentrations of polybrominated diphenyl ethers, hexachlorobenzene and polycyclic aromatic hydrocarbons in various foodstuffs before and after cooking.
  186. Influence of various cooking processes on the concentrations of PCDD/PCDFs, PCBs and PCDEs in foods
  187. Meat consumption and cancer risk: a critical review of published meta-analyses
  188. The World Cancer Research Fund report 2007: A challenge for the meat processing industry
  189. Meat subtypes and their association with colorectal cancer: Systematic review and meta-analysis
  190. Processed meat: the real villain?
  191. Meat: The balance between nutrition and health. A review
  192. Mechanisms Linking Colorectal Cancer to the Consumption of (Processed) Red Meat: A Review
  193. A critical overview on the biological and molecular features of red and processed meat in colorectal carcinogenesis
  194. Potential health hazards of eating red meat
  195. Cancer incidence attributable to red and processed meat consumption in Alberta in 2012
  196. The impact of red and processed meat consumption on cancer and other health outcomes: Epidemiological evidences
  197. Animal foods
  198. Diet and the risk of head-and-neck cancer among never-smokers and smokers in a Chinese population
  199. A review and meta-analysis of prospective studies of red and processed meat, meat cooking methods, heme iron, heterocyclic amines and prostate cancer
  200. Food of animal origin and risk of non-Hodgkin lymphoma and multiple myeloma: A review of the literature and meta-analysis

Red and processed meat consumption and risk of bladder cancer: a dose–response meta-analysis of epidemiological studies

  1. Red and processed meat consumption and mortality: dose–response meta-analysis of prospective cohort studies
  2. Association Between Consumption of Red and Processed Meat and Pancreatic Cancer Risk: A Systematic Review and Meta-analysis
  3. The cancer risk related to meat and meat products
  4. Consumption of Red/Processed Meat and Colorectal Carcinoma: Possible Mechanisms Underlying the Significant Association
  5. A red meat-derived glycan promotes inflammation and cancer progression
  6. Red and processed meat, nitrite, and heme iron intakes and postmenopausal breast cancer risk in the NIH-AARP Diet and Health Study
  7. Human risk of diseases associated with red meat intake: Analysis of current theories and proposed role for metabolic incorporation of a non-human sialic acid
  8. Meat intake, cooking methods and doneness and risk of colorectal tumours in the Spanish multicase-control study (MCC-Spain)
  9. Increased oxidative and nitrosative reactions during digestion could contribute to the association between well-done red meat consumption and colorectal cancer
  10. Polycyclic Aromatic Hydrocarbons (PAHs) and their Bioaccessibility in Meat: a Tool for Assessing Human Cancer Risk
  11. European Code against Cancer 4th Edition: Diet and cancer
  12. Meat, Fish, Poultry, and Egg Intake at Diagnosis and Risk of Prostate Cancer Progression
  13. Iron deficiency anaemia
  14. Occupational Safety and Health Administration
  15. Effect of egg ingestion on trimethylamine-N-oxide production in humans: a randomized, controlled, dose-response study.
  16. Formation of methylamines from ingested choline and lecithin.
  17. TMAO: A small molecule of great expectations
  18. Plasma choline metabolites and colorectal cancer risk in the Women’s Health Initiative Observational Study.
  19. Rescue of the neuroblastoma mutant of the human nucleoside diphosphate kinase A/nm23-H1 by the natural osmolyte trimethylamine-N-oxide
  20. Substrate rescue of DNA polymerase beta containing a catastrophic L22P mutation.
  21. N-Glycolylneuraminic acid in human tumours
  22. Dietary Components Related to N-Nitroso Compound Formation: A Prospective Study of Adult Glioma
  23. Oral AGE restriction ameliorates insulin resistance in obese individuals with the metabolic syndrome: a randomised controlled trial
  24. Nutritional Intake of Vitamins K1 (Phylloquinone) and K2 (Menaquinone) in The Netherlands
  25. Dietary Intake of Menaquinone Is Associated with a Reduced Risk of Coronary Heart Disease: The Rotterdam Study
  26. Iron in red meat-friend or foe.
  27. Food groups and risk of colorectal cancer.

Further Reading:

  1. https://examine.com/nutrition/is-processed-meat-bad-for-me/
  2. https://examine.com/nutrition/scientists-just-found-that-red-meat-causes-cancer–or-did-they/
  3. https://examine.com/nutrition/does-red-meat-cause-cancer/
  4. https://examine.com/nutrition/how-can-i-make-red-meat-healthier/

More on nitrate:

  1. http://pubs.rsc.org/en/content/articlelanding/1975/c310.1039/c39750000884#!divAbstract
  2. https://examine.com/supplements/nitrate/

More on L-carnitine:

  1. https://examine.com/supplements/l-carnitine/

More on vitamin K2:

  1. https://honey-guide.com/2014/03/10/menaquinones-k2-and-phylloquinone-k1-content-of-animal-products-and-fermented-foods/
  2. http://www.k-vitamins.com/index.php?page=Cancer
  3. The Ultimate Vitamin K2 Resource
  4. https://wholehealthsource.blogspot.com/search?q=vitamin+k2

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