Should dietary guidelines recommend low red meat intake? Short answer: no!


(Michael - Don't expect miracles and you won't be disappointed.) #1

Abstract

Mainstream dietary recommendations now commonly advise people to minimize the intake of red meat for health and environmental reasons. Most recently, a major report issued by the EAT-Lancet Commission recommended a planetary reference diet mostly based on plants and with no or very low (14 g/d) consumption of red meat. We argue that claims about the health dangers of red meat are not only improbable in the light of our evolutionary history, they are far from being supported by robust scientific evidence.

Critical Reviews in Food Science and Nutrition

Source Journal

For anyone who has a problem accessing the above links, I have incorporated the entire article and references below. I had to do so in multiple posts, since there is a 32K limit for each post.


(Joey) #2

@amwassil Thanks for sharing the abstract & link … Looks like it would be an interesting read although I can’t seem to easily access the paper itself (perhaps due to my browser settings?)

Was there a study of some kind performed or was this a commentary/opinion?


(Michael - Don't expect miracles and you won't be disappointed.) #3

@SomeGuy The article is a response/rebuttal to the EAT-Lancet Commission formal directive for a Great Food Transformation toward a predominantly plant-based diet for the planet based on Willett et al., 2019. It hammers every single claim/recommendation by EAT-Lancet and is really too detailed to summarize. It’s a great article with links to multiple references (175 total!).

Maybe this link will work for you. Select the ‘View Full Text’ link at upper right. It displays the same link I provided above, but who knows, maybe it will work.

I also might be able to attach it somehow, maybe as a ‘wiki’. I’ll what I can do with it.


(Michael - Don't expect miracles and you won't be disappointed.) #4

tandfonline.com

Should dietary guidelines recommend low red meat intake?

Nathan Cofnas

82-104 minutes

1. Introduction

On January 16th, 2019, the EAT-Lancet Commission formally expressed its desire for a Great Food Transformation toward a predominantly plant-based diet for the planet (Willett et al., 2019 , Johan Rockström, Brent Loken, Marco Springmann, Tim Lang, Sonja Vermeulen, Tara Garnett, David Tilman, Fabrice DeClerck, Amanda Wood., et al. 2019. Food in the anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet 393 (10170):447–92. doi: 10.1016/S0140-6736(18)31788-4.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). The proposed reference diet includes minute daily doses of beef (7 g), pork (7 g), and eggs (13 g), with somewhat larger amounts of poultry (29 g) and fish (28 g). Despite heavy restrictions on other animal source foods, it allows for 250 g of dairy products per day, with a limit of 153 kcal. Stricter vegetarian and even vegan diets were sanctioned as valid options too, provided that vitamin B12 supplements are taken in the case of veganism. In the words of the Commission: “This healthy reference diet…includes a low to moderate amount of seafood and poultry, and includes no or a low quantity of red meat, processed meat” (Willett et al., 2019 Willett, Walter, Johan Rockström, Brent Loken, Marco Springmann, Tim Lang, Sonja Vermeulen, Tara Garnett, David Tilman, Fabrice DeClerck, Amanda Wood., et al. 2019. Food in the anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet 393 (10170):447–92. doi: 10.1016/S0140-6736(18)31788-4.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). One of the “key messages” is that “Healthy diets…consist of a diversity of plant-based foods, low amounts of animal source foods.” Red meat is specifically labeled as an “unhealthy food”. While the authors acknowledge that livestock products can offer benefits for those who are nutritionally deficient, a strong reduction of animal products was said to be beneficial for both health and the environment. Soon after the release of this EAT-Lancet report, a similar argument was made by yet another Lancet Commission, classifying meat as a driver of the Global Syndemic —a system of interconnected global crises related to health and the environment—and arguing for an interventionist approach through mass-marketing campaigns and legal measures, including the mandatory use of warning labels and the application of taxes (Swinburn et al., 2019 Swinburn, Boyd A., Vivica I. Kraak, Steven Allender, Vincent J. Atkins, Phillip I. Baker, Jessica R. Bogard, Hannah Brinsden, Alejandro Calvillo, Olivier De Schutter, Raji Devarajan., et al. 2019. The global syndemic of obesity, undernutrition, and climate change: the Lancet Commission report. Lancet 393 (10173):791–846. doi: 10.1016/S0140-6736(18)32822-8.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Previously, other groups associated with the EAT-Lancet Commission have made similar recommendations. A study whose first author belongs to the EAT-Lancet Commission recently called for taxes on meat consumption (Springmann et al., 2018 Springmann, Marco, Daniel Mason-D’Croz, Sherman Robinson, Keith Wiebe, H. Charles J. Godfray, Mike Rayner, and Peter Scarborough. 2018. Health-motivated taxes on red and processed meat: a modelling study on optimal tax levels and associated health impacts. PLOS ONE 13 (11):e0204139. doi: 10.1371/journal.pone.0204139.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). The World Research Institute, a direct partner of the EAT-Lancet network, considers various interventions to reduce meat eating with varying degrees of compulsion ( e.g ., influencing nutritional labeling and dietary guidelines, stimulating 30-day diet challenges, imposing taxes, and banning meat from menus) (Ranganathan et al., 2016 Ranganathan, J., D. Vennard, R. Waite, B. Lipinski, T. Searchinger, and P. Dumas. 2016. Shifting diets for a sustainable food future. https://wriorg.s3.amazonaws.com/s3fs-public/Shifting_Diets_for_a_Sustainable_Food_Future_1.pdf?_ga=2.114696014.831878447.1548317259-387216062.1543582872. [Google Scholar]).

Contemporary arguments against meat eating appeal mostly to nutritional, environmental, and ethical considerations (Leroy, 2019 Leroy, F. 2019. Meat as a pharmakon: an exploration of the biosocial complexities of meat consumption. Advances in Food and Nutrition Research 87:409–46.[Crossref], [PubMed] , [Google Scholar]). The present review focuses on nutrition. Although the environmental and ethical arguments should certainly not be overlooked, these require separate analyses. Furthermore, the nutritional debate has its own complexities and controversies, for instance with respect to the potential health implications of shifts in macronutrient ratios toward elevated levels of carbohydrates ( e.g. , Deghan et al., 2017 Deghan, M., A. Mente, X. Zhang, S. Swaminathan, W. Li, V. Mohan., et al. 2017. Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study. Lancet 39:2050–62.[Crossref] , [Google Scholar]) or the reliance on ample amounts of cereals ( e.g ., Antvorskov et al., 2018 Antvorskov, Julie C., Thorhallur I. Halldorsson, Knud Josefsen, Jannet Svensson, Charlotta Granström, Bart O. Roep, Trine H. Olesen, Laufey Hrolfsdottir, Karsten Buschard, and Sjudur F. Olsen. 2018. Association between maternal gluten intake and type 1 diabetes in offspring: national prospective cohort study in Denmark. BMJ 362:k3547. doi: 10.1136/bmj.k3547.[Crossref], [PubMed] , [Google Scholar]), soy ( e.g ., Siepmann et al., 2011 Siepmann, T., J. Roofeh, F. W. Kiefer, and D. G. Edelson. 2011. Hypogonadism and erectile dysfunction associated with soy product consumption. Nutrition 27 (7-8):859–62.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), and plant oils ( e.g ., DiNicolantonio, 2014 DiNicolantonio, J. J. 2014. The cardiometabolic consequences of replacing saturated fats with carbohydrates or Ω-6 polyunsaturated fats: do the dietary guidelines have it wrong? Open Heart 1 (1):e000032doi: 10.1136/openhrt-2013-000032.[Crossref], [PubMed] , [Google Scholar]). The present overview, therefore, will be dedicated to the specific topic of severe meat restriction or avoidance and the potential impact of such dietary restriction on health. Ultimately, the conclusions will have to be integrated into a more holistic evaluation that balances nutrition, sustainability, and ethics.


(Michael - Don't expect miracles and you won't be disappointed.) #5

2. Meat and health: a shifting paradigm? [1 of 2]

Humans are biologically adapted to a diet that includes meat. Archeological findings suggest that hominins were butchering animals with stone tools 2.5 million years ago (de Heinzelin et al., 1999 de Heinzelin, J., J. D. Clark, T. White, W. Hart, P. Renne, G. WoldeGabriel, Y. Beyene, and E. Vrba. 1999. Environment and behavior of 2.5-million-year-old bouri hominids. Science 284 (5414):625–9. doi: 10.1126/science.284.5414.625.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). At some point we lost the ability to absorb vitamin B12 in the large intestine, where it is produced by gut bacteria, making man dependent on dietary sources of the vitamin (Schjønsby, 1989 Schjønsby, H. 1989. Vitamin B12 absorption and malabsorption. Gut 30 (12):1686–91. doi: 10.1136/gut.30.12.1686.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Presumably our ancestors were able to survive losing this ability because they were regularly consuming B12-rich meat (Lents, 2018 Lents, N.H. 2018. The evolutionary quirk that made vitamin B12 part of our diet. Discover . http://blogs.discovermagazine.com/crux/2018/08/13/vitamin-b12-essential/#.XUMXUOgzY2w. [Google Scholar]). Hominin skeletal remains from 1.5 million years ago show signs of porotic hyperostosis, which is generally linked to B12 deficiency and is virtually absent in chimpanzees who still obtain B12 from gut bacteria (Domínguez-Rodrigo et al., 2012 Domínguez-Rodrigo, Manuel, Travis Rayne Pickering, Fernando Diez-Martín, Audax Mabulla, Charles Musiba, Gonzalo Trancho, Enrique Baquedano, Henry T. Bunn, Doris Barboni, Manuel Santonja., et al. 2012. Earliest porotic hyperostosis on a 1.5-million-year-old hominin, olduvai gorge, tanzania. PLOS ONE 7 (10):e46414. doi: 10.1371/journal.pone.0046414.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). This provides some evidence that “by at least the early Pleistocene meat had become so essential to proper hominin functioning that its paucity or lack led to deleterious pathological conditions” (Domínguez-Rodrigo et al., 2012 Domínguez-Rodrigo, Manuel, Travis Rayne Pickering, Fernando Diez-Martín, Audax Mabulla, Charles Musiba, Gonzalo Trancho, Enrique Baquedano, Henry T. Bunn, Doris Barboni, Manuel Santonja., et al. 2012. Earliest porotic hyperostosis on a 1.5-million-year-old hominin, olduvai gorge, tanzania. PLOS ONE 7 (10):e46414. doi: 10.1371/journal.pone.0046414.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Over time our capacity to convert the omega-3 fatty acid alpha-linolenic acid (ALA), found in plants, to the biologically important eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) forms (found primarily in seafood, but also in meat, eggs, and dairy; Tur et al., 2012 Tur, J. A., M. M. Bibiloni, A. Sureda, and A. Pons. 2012. Dietary sources of omega 3 fatty acids: public health risks and benefits. British Journal of Nutrition 107 (S2):S23–S52. doi: 10.1017/S0007114512001456.[Crossref], [PubMed] , [Google Scholar]) became greatly reduced in comparison to other primates (Stark et al., 2016 Stark, A. H., R. Reifen, and M. A. Crawford. 2016. Past and present insights on alpha-linolenic acid and the omega-3 fatty acid family. Critical Reviews in Food Science and Nutrition 56 (14):2261–7. doi: 10.1080/10408398.2013.828678[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]). The shift to energy-dense meat caused our guts, particularly our large intestines, to shrink significantly compared to those of apes. Gut proportions in humans are also adapted to meat eating. Our small intestine (in which most nutrients are extracted) comprises 56% of total gut volume, while the large intestine comprises about 20%—these proportions are reversed in apes (Milton, 2003 Milton, K. 2003. The critical role played by animal source foods in human (Homo) evolution. The Journal of Nutrition 133 (11 Suppl 2):3886S–92S. doi: 10.1093/jn/133.11.3886S.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Meat eating, and the concomitant reduction in size of the energy-consuming gut, is believed to have played an essential role in the increase of brain size in the hominin lineage. Because the brain and gut compete for energy, the former was able to increase in size when the latter became smaller (Aiello & Wheeler, 1995 Aiello, L. C., and P. Wheeler. 1995. The expensive-tissue hypothesis: the brain and the digestive system in human and primate evolution. Current Anthropology 36 (2):199–221. doi: 10.1086/204350.[Crossref], [Web of Science ®] , [Google Scholar]). Gupta (2016 Gupta, S. 2016. Brain food: clever eating. Nature 531 (7592):S12–S13. doi: 10.1038/531S12a.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) expounds: “To build and maintain a more complex brain, our ancestors used ingredients found primarily in meat, including iron, zinc, vitamin B12 and fatty acids. Although plants contain many of the same nutrients, they occur in lower quantities and often in a form that humans cannot readily use.”


(Michael - Don't expect miracles and you won't be disappointed.) #6

2. Meat and health: a shifting paradigm? [2 of 2]

The fact that we are biologically adapted to diets that include substantial amounts of meat does not by itself prove that low-meat diets cannot be healthy. However, when it comes to virtually every other species, we generally take it for granted that it will flourish best on a diet that roughly resembles the one to which it was adapted. It would be, though not impossible, somewhat surprising if Homo sapiens turned out to be such a spectacular exception to this principle. Nevertheless, mainstream nutrition discourse often portrays meat as a health disaster (see Leroy, 2019 Leroy, F. 2019. Meat as a pharmakon: an exploration of the biosocial complexities of meat consumption. Advances in Food and Nutrition Research 87:409–46.[Crossref], [PubMed] , [Google Scholar]), suggesting that it can be readily replaced with legumes and B12 supplements, and whereby additional confusion is generated by sensationalist misrepresentations of the scientific evidence in mass media (Leroy et al., 2018a Leroy, F., M. Brengman, W. Ryckbosch, and P. Scholliers. 2018. Meat in the post-truth era: mass media discourses on health and disease in the attention economy. Appetite 125:345–55. doi: 10.1016/j.appet.2018.02.028.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Nonetheless, the anti-meat discourse is able to refer to a large set of international and peer-reviewed scientific data that have been institutionalized in dietary advice from various health authorities worldwide ( e.g ., WHO, 2015 WHO 2015. Q&A on the carcinogenicity of the consumption of red meat and processed meat. http://www.who.int/features/qa/cancer-red-meat/en [Google Scholar]; NHS, 2018 NHS 2018. 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Red and processed meat intake and risk of esophageal adenocarcinoma: a meta-analysis of observational studies. Cancer Causes & Control 24 (1):193–201. doi: 10.1007/s10552-012-0105-9.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Farvid et al., 2015 Farvid, M. S., E. Cho, W. Y. Chen, A. H. Eliassen, and W. C. Willett. 2015. Adolescent meat intake and breast cancer risk. International Journal of Cancer 136 (8):1909–20. doi: 10.1002/ijc.29218.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Carr et al., 2016 Carr, P. R., V. Walter, H. Brenner, and M. Hoffmeister. 2016. Meat subtypes and their association with colorectal cancer: systematic review and meta-analysis. International Journal of Cancer 138 (2):293–302. doi: 10.1002/ijc.29423.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), and intestinal disorders (Cao et al., 2018 Cao, Y., L. L. Strate, B. R. Keeley, I. Tam, K. Wu, E. L. Giovannucci, and A. T. Chan. 2018. Meat intake and risk of diverticulitis among men. Gut 67 (3):466–72. doi: 10.1136/gutjnl-2016-313082.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). The above-mentioned Lancet reports (Swinburn et al., 2019 Swinburn, Boyd A., Vivica I. Kraak, Steven Allender, Vincent J. Atkins, Phillip I. Baker, Jessica R. Bogard, Hannah Brinsden, Alejandro Calvillo, Olivier De Schutter, Raji Devarajan., et al. 2019. The global syndemic of obesity, undernutrition, and climate change: the Lancet Commission report. Lancet 393 (10173):791–846. doi: 10.1016/S0140-6736(18)32822-8.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Willett et al., 2019 Willett, Walter, Johan Rockström, Brent Loken, Marco Springmann, Tim Lang, Sonja Vermeulen, Tara Garnett, David Tilman, Fabrice DeClerck, Amanda Wood., et al. 2019. Food in the anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet 393 (10170):447–92. doi: 10.1016/S0140-6736(18)31788-4.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) make recommendations based on this research, assuming causal relationships between meat intake and morbidity and mortality.


(Michael - Don't expect miracles and you won't be disappointed.) #7

3. Meat eating and chronic disease: evaluation of the evidence

3.1. Evidence from observational studies needs to be interpreted with care [1 of 2]

Despite the merits of epidemiology as a scientific discipline, an overwhelming corpus of often non-robust and overstated observational findings has been amassing over the last decades in the field of nutrition (Ioannidis, 2018 Ioannidis, J. P. A. 2018. The challenge of reforming nutritional epidemiologic research. JAMA 320 (10):969–70. doi: 10.1001/jama.2018.11025.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Naïve interpretations of these findings are often promoted by the media and influence nutritional guidelines. Ioannidis illustrates the absurdity of taking them at face value:

Assuming the meta-analyzed evidence from cohort studies represents life span-long causal associations, for a baseline life expectancy of 80 years, eating 12 hazelnuts daily (1 oz) would prolong life by 12 years (i.e., 1 year per hazelnut), drinking 3 cups of coffee daily would achieve a similar gain of 12 extra years, and eating a single mandarin orange daily (80 g) would add 5 years of life. Conversely, consuming 1 egg daily would reduce life expectancy by 6 years, and eating 2 slices of bacon (30 g) daily would shorten life by a decade, an effect worse than smoking. (Ioannidis, 2018 Ioannidis, J. P. A. 2018. The challenge of reforming nutritional epidemiologic research. JAMA 320 (10):969–70. doi: 10.1001/jama.2018.11025.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar])

Schoenfeld and Ioannidis (2013 Schoenfeld, J. D., and J. P. A. Ioannidis. 2013. Is everything we eat associated with cancer? a systematic cookbook review. The American Journal of Clinical Nutrition 97 (1):127–34. doi: 10.3945/ajcn.112.047142.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) found that, among 50 common ingredients used in a cookbook, 40 had been associated with cancer risk or benefit based on observational studies.

As a first point of concern, the input data obtained from food frequency questionnaires should be interpreted prudently as they can be problematic for a variety of reasons (Schatzkin et al., 2003 Schatzkin, Arthur, Victor Kipnis, Raymond J. Carroll, Douglas Midthune, Amy F. Subar, Sheila Bingham, Dale A. Schoeller, Richard P. Troiano, and Laurence S. Freedman. 2003. A comparison of a food frequency questionnaire with a 24-hour recall for use in an epidemiological cohort study: results from the biomarker-based observing protein and energy nutrition (OPEN) study. International Journal of Epidemiology 32 (6):1054–62. doi: 10.1093/ije/dyg264.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Archer et al., 2018 Archer, E., M. L. Marlow, and C. J. Lavie. 2018. Controversy and debate: memory based methods paper 1: the fatal flaws of food frequency questionnaires and other memory-based dietary assessment methods. Journal of Clinical Epidemiology 104:113–24. doi: 10.1016/j.jclinepi.2018.08.003.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Feinman, 2018 Feinman, R. 2018. What’s really wrong with medical research and how to fix it. Journal of Evolution and Health 2 (3):10. doi: 10.15310/2334-3591.1069.[Crossref] , [Google Scholar]). Social desirability bias in food reporting is just one example, as reported consumption can be affected by the perceived health status of certain foods. Not all self-defined vegetarians avoid meat, which is suggestive of a considerable risk for underreported intake in health-conscious groups (Haddad & Tanzman, 2003 Haddad, E. H., and J. S. Tanzman. 2003. What do vegetarians in the United States eat? The American Journal of Clinical Nutrition 78 (3):626S–32S. doi: 10.1093/ajcn/78.3.626S.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]).

Secondly, diets are difficult to disentangle from other lifestyle factors. It has been shown that Western-style meat eating is closely associated with nutrient-poor diets, obesity, smoking, and limited physical activity (Alexander et al., 2015 Alexander, D. D., D. L. Weed, P. E. Miller, and M. A. Mohamed. 2015. Red meat and colorectal cancer: a quantitative update on the state of the epidemiologic science. Journal of the American College of Nutrition 34 (6):521–43. doi: 10.1080/07315724.2014.992553.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]; Fogelholm et al., 2015 Fogelholm, M., N. Kanerva, and S. Männistö. 2015. Association between red and processed meat consumption and chronic diseases: the confounding role of other dietary factors. European Journal of Clinical Nutrition 69 (9):1060–5. doi: 10.1038/ejcn.2015.63.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Grosso et al., 2017 Grosso, G., A. Micek, J. Godos, A. Pajak, S. Sciacca, F. Galvano, and P. Boffetta. 2017. Health risk factors associated with meat, fruit and vegetable consumption in cohort studies: a comprehensive meta-analysis. PLOS ONE 12 (8):e0183787. doi: 10.1371/journal.pone.0183787.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Turner & Lloyd, 2017 Turner, N. D., and S. K. Lloyd. 2017. Association between red meat consumption and colon cancer: a systematic review of experimental results. Experimental Biology and Medicine 242 (8):813–39. doi: 10.1177/1535370217693117.[Crossref], [Web of Science ®] , [Google Scholar]). Given the fact that health authorities have been intensely promoting the view that meat is unhealthy, health-conscious people may be inclined to reduce intake. Typically, the associations between meat eating and disease tend to be higher in North American than in European or Asian cohort studies, indicating the presence of lifestyle bias and the need for cross-cultural assessments (Wang et al., 2016 Wang, X., X. Lin, Y. Y. Ouyang, J. Liu, G. Zhao, A. Pan, and F. B. Hu. 2016. Red and processed meat consumption and mortality: dose-response meta-analysis of prospective cohort studies. Public Health Nutrition 19 (5):893–905. doi: 10.1017/S1368980015002062.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Grosso et al., 2017 Grosso, G., A. Micek, J. Godos, A. Pajak, S. Sciacca, F. Galvano, and P. Boffetta. 2017. Health risk factors associated with meat, fruit and vegetable consumption in cohort studies: a comprehensive meta-analysis. PLOS ONE 12 (8):e0183787. doi: 10.1371/journal.pone.0183787.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Hur et al., 2018 Hur, S. J., C. Jo, Y. Yoon, J. Y. Jeong, and K. T. Lee. 2018. Controversy on the correlation of red and processed meat consumption with colorectal cancer risk: an asian perspective. Critical Reviews in Food Science and Nutrition . doi: 10.1080/10408398.2018.1495615.[Taylor & Francis Online] , [Google Scholar]). A pooled analysis of prospective cohort studies in Asian countries even indicated that red meat intake was associated with lower cardiovascular mortality in men and cancer mortality in women (Lee et al., 2013 Lee, Jung Eun., Dale F. McLerran, Betsy Rolland, Yu Chen, Eric J. Grant, Rajesh Vedanthan, Manami Inoue, Shoichiro Tsugane, Yu-Tang Gao, Ichiro Tsuji., et al. 2013. Meat intake and cause-specific mortality: a pooled analysis of asian prospective cohort studies. The American Journal of Clinical Nutrition 98 (4):1032–41. doi: 10.3945/ajcn.113.062638.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Likewise, when omitting Seventh-Day Adventist studies from meta-analyses, the beneficial associations with cardiovascular health for vegetarian diets are either less pronounced or absent indicating the specific effects of health-conscious lifestyle rather than low meat consumption as such (Kwok et al., 2014 Kwok, C. S., S. Umar, P. K. Myint, M. A. Mamas, and Y. K. Loke. 2014. Vegetarian diet, seventh day adventists and risk of cardiovascular mortality: a systematic review and meta-analysis. International Journal of Cardiology 176 (3):680–6. doi: 10.1016/j.ijcard.2014.07.080.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; FCN, 2018). This is important, as Seventh-Day Adventism has had considerable influence on dietary advice worldwide (Banta et al., 2018 Banta, J. E., J. W. Lee, G. Hodgkin, Z. Yi, A. Fanica, and J. Sabate. 2018. The global influence of the Seventh-day Adventist Church on diet. Religions 9 (9):251. doi: 10.3390/rel9090251.[Crossref], [Web of Science ®] , [Google Scholar]).


(Michael - Don't expect miracles and you won't be disappointed.) #8

3. Meat eating and chronic disease: evaluation of the evidence

3.1. Evidence from observational studies needs to be interpreted with care [2 of 2]

As a third point, the relative risks (RRs) obtained from observational studies are generally low, i.e ., much below 2. In view of the profusion of false-positive findings and the large uncertainty and bias in the data due to the problems mentioned above (Boffetta et al., 2008 Boffetta, P., J. K. McLaughlin, C. La Vecchia, R. E. Tarone, L. Lipworth, and W. J. Blot. 2008. False-positive results in cancer epidemiology: a plea for epistemological modesty. Journal of the National Cancer Institute 100 (14):988–95. doi: 10.1093/jnci/djn191.[Crossref], [PubMed] , [Google Scholar]; Young & Karr, 2011 Young, S. S., and A. Karr. 2011. Deming, data and observational studies. Significance 8 (3):116–20. doi: 10.1111/j.1740-9713.2011.00506.x.[Crossref] , [Google Scholar]), such low RR levels in isolation would not be treated as strong evidence in most epidemiological research outside nutrition (Shapiro, 2004 Shapiro, S. 2004. Looking to the 21st century: have we learned from our mistakes, or are we doomed to compound them?. Pharmacoepidemiology and Drug Safety 13 (4):257–65. doi: 10.1002/pds.903.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Klurfeld, 2015 Klurfeld, D. M. 2015. Research gaps in evaluating the relationship of meat and health. Meat Science 109:86–95. doi: 10.1016/j.meatsci.2015.05.022.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Relationships with RRs below 2, which are susceptible to confounding, can be indicative but should always be validated by other means, such as randomized controlled trials (RCTs) (Gerstein et al., 2019 Gerstein, H. C., J. McMurray, and R. R. Holman. 2019. Real-world studies no substitute for RCTs in establishing efficacy. Lancet 393 (10168):210–1. doi: 10.1016/S0140-6736(18)32840-X.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). The association between meat eating and colorectal cancer, for instance, leads to an RR estimate below 1.2, whereas for the association between visceral fat and colorectal neoplasia this value equals 5.9 (Yamamoto et al., 2010 Yamamoto, S., T. Nakagawa, Y. Matsushita, S. Kusano, T. Hayashi, M. Irokawa, T. Aoki, Y. Korogi, and T. Mizoue. 2010. Visceral fat area and markers of insulin resistance in relation to colorectal neoplasia. Diabetes Care 33 (1):184–9. doi: 10.2337/dc09-1197.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). The latter provides a robust case that is much more deserving of priority treatment in health policy development.

To sum up, the case propagated by the EAT-Lancet Commission (Willett et al., 2019 Willett, Walter, Johan Rockström, Brent Loken, Marco Springmann, Tim Lang, Sonja Vermeulen, Tara Garnett, David Tilman, Fabrice DeClerck, Amanda Wood., et al. 2019. Food in the anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet 393 (10170):447–92. doi: 10.1016/S0140-6736(18)31788-4.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) has essentially been based on observational studies with RRs much below 2 ( e.g. , Sinha et al., 2009 Sinha, R., A. J. Cross, B. I. Graubard, M. F. Leitzmann, and A. Schatzkin. 2009. Meat intake and mortality: a prospective study of over half a million people. Archives of Internal Medicine 169 (6):562–71. doi: 10.1001/archinternmed.2009.6.[Crossref], [PubMed] , [Google Scholar]; Pan et al., 2011 Pan, A., Q. Sun, A. M. Bernstein, M. B. Schulze, J. E. Manson, W. C. Willett, and F. B. Hu. 2011. Red meat consumption and risk of type 2 diabetes: 3 cohorts of US adults and an updated meta-analysis. The American Journal of Clinical Nutrition 94 (4):1088–96. doi: 10.3945/ajcn.111.018978.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar], 2012 Pan, A., Q. Sun, A. M. Bernstein, M. B. Schulze, J. E. Manson, M. J. Stampfer., et al. 2012. Red meat consumption and mortality: results from 2 prospective cohort studies. Archives of Internal Medicine 172:555–63. doi: 10.1001/archinternmed.2011.2287.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Chen et al., 2013 Chen, G. C., D. B. Lv, Z. Pang, and Q. F. Liu. 2013. Red and processed meat consumption and risk of stroke: a meta-analysis of prospective cohort studies. European Journal of Clinical Nutrition 67 (1):91–5. doi: 10.1038/ejcn.2012.180.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Feskens et al., 2013 Feskens, E. J., D. Sluik, and G. J. van Woudenbergh. 2013. Meat consumption, diabetes, and its complications. Current Diabetes Reports 13 (2):298–306. doi: 10.1007/s11892-013-0365-0.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Lee et al., 2013 Lee, Jung Eun., Dale F. McLerran, Betsy Rolland, Yu Chen, Eric J. Grant, Rajesh Vedanthan, Manami Inoue, Shoichiro Tsugane, Yu-Tang Gao, Ichiro Tsuji., et al. 2013. Meat intake and cause-specific mortality: a pooled analysis of asian prospective cohort studies. The American Journal of Clinical Nutrition 98 (4):1032–41. doi: 10.3945/ajcn.113.062638.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Abete et al., 2014 Abete, I., D. Romaguera, A. R. Vieira, A. Lopez de Munain, and T. Norat. 2014. Association between total, processed, red and white meat consumption and all-cause, CVD and IHD mortality: a meta-analysis of cohort studies. British Journal of Nutrition 112 (5):762–75. doi: 10.1017/S000711451400124X.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Farvid et al., 2015 Farvid, M. S., E. Cho, W. Y. Chen, A. H. Eliassen, and W. C. Willett. 2015. Adolescent meat intake and breast cancer risk. International Journal of Cancer 136 (8):1909–20. doi: 10.1002/ijc.29218.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Etemadi et al., 2017 Etemadi, A., R. Sinha, M. H. Ward, B. I. Graubard, M. Inoue-Choi, S. M. Dawsey, and C. C. Abnet. 2017. Mortality from different causes associated with meat, heme iron, nitrates, and nitrites in the NIH-AARP diet and health study: population based cohort study. BMJ 357:j1957. doi: 10.1136/bmj.j1957[Crossref], [PubMed] , [Google Scholar]). We find this particularly problematic, as it is not good practice to infer a causal connection to meat eating from such weak and confounded associational data (McAfee et al., 2010 McAfee, A. J., E. M. McSorley, G. J. Cuskelly, B. W. Moss, J. M. Wallace, M. P. Bonham, and A. M. Fearon. 2010. Red meat consumption: an overview of the risks and benefits. Meat Science 84 (1):1–13. doi: 10.1016/j.meatsci.2009.08.029.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Alexander et al., 2015 Alexander, D. D., D. L. Weed, P. E. Miller, and M. A. Mohamed. 2015. Red meat and colorectal cancer: a quantitative update on the state of the epidemiologic science. Journal of the American College of Nutrition 34 (6):521–43. doi: 10.1080/07315724.2014.992553.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]; Klurfeld, 2015 Klurfeld, D. M. 2015. Research gaps in evaluating the relationship of meat and health. Meat Science 109:86–95. doi: 10.1016/j.meatsci.2015.05.022.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Feinman, 2018 Feinman, R. 2018. What’s really wrong with medical research and how to fix it. Journal of Evolution and Health 2 (3):10. doi: 10.15310/2334-3591.1069.[Crossref] , [Google Scholar]; Leroy et al., 2018b Leroy, Frédéric, Teresa Aymerich, Marie-Christine Champomier-Vergès, Luca Cocolin, Luc De Vuyst, Mónica Flores, Françoise Leroi, Sabine Leroy, Régine Talon, Rudi F. Vogel., et al. 2018. Fermented meats (and the symptomatic case of the flemish food pyramid): are we heading towards the vilification of a valuable food group?. International Journal of Food Microbiology 274:67–70. doi: 10.1016/j.ijfoodmicro.2018.02.006.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Moreover, the science used to incorporate the data from meat studies into dietary policy making is all-too often partial and inaccurate (Truswell, 2009 Truswell, A. S. 2009. Problems with red meat in the WCRF2. The American Journal of Clinical Nutrition 89 (4):1274–5. doi: 10.3945/ajcn.2008.27201.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). This concern is underlined by the fact that claims from observational epidemiology very often fail to hold up when tested in RCTs (Young & Karr, 2011 Young, S. S., and A. Karr. 2011. Deming, data and observational studies. Significance 8 (3):116–20. doi: 10.1111/j.1740-9713.2011.00506.x.[Crossref] , [Google Scholar]). Nutritional epidemiology is a useful tool for the generation of hypotheses, but its findings as such do not provide a robust basis for the implementation of health policies in the absence of further substantiation. Or, as stated by Gerstein et al. (2019 Gerstein, H. C., J. McMurray, and R. R. Holman. 2019. Real-world studies no substitute for RCTs in establishing efficacy. Lancet 393 (10168):210–1. doi: 10.1016/S0140-6736(18)32840-X.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), “analyses of most observational data from the real world, regardless of their sophistication, can only be viewed as hypothesis generating”. This is especially so when the results are counterintuitive, as is the case for meat eating given its long record as an essential food within our species-adapted diet.


(Michael - Don't expect miracles and you won't be disappointed.) #9

3. Meat eating and chronic disease: evaluation of the evidence

3.2. Intervention studies have not been able to indicate unambiguous detrimental effects [1 of 2]

As stated by Abete et al. (2014 Abete, I., D. Romaguera, A. R. Vieira, A. Lopez de Munain, and T. Norat. 2014. Association between total, processed, red and white meat consumption and all-cause, CVD and IHD mortality: a meta-analysis of cohort studies. British Journal of Nutrition 112 (5):762–75. doi: 10.1017/S000711451400124X.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), epidemiological findings on meat eating “should be interpreted with caution due to the high heterogeneity observed in most of the analyses as well as the possibility of residual confounding”. The interactions between meat, overall diet, human physiology (including the gut microbiome), and health outcomes are highly intricate. Within this web of complexity, and in contrast to what is commonly stated in the public domain (Leroy et al., 2018a Leroy, F., M. Brengman, W. Ryckbosch, and P. Scholliers. 2018. Meat in the post-truth era: mass media discourses on health and disease in the attention economy. Appetite 125:345–55. doi: 10.1016/j.appet.2018.02.028.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), the current epidemiological and mechanistic data have not been able to demonstrate a consistent causal link between red meat intake and chronic diseases, such as colorectal cancer (Oostindjer et al., 2014 Oostindjer, Marije, Jan Alexander, Gro V. Amdam, Grethe Andersen, Nathan S. Bryan, Duan Chen, Denis E. Corpet, Stefaan De Smet, Lars Ove Dragsted, Anna Haug., et al. 2014. The role of red and processed meat in colorectal cancer development: a perspective. Meat Science 97 (4):583–96. doi: 10.1016/j.meatsci.2014.02.011.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Turner & Lloyd, 2017 Turner, N. D., and S. K. Lloyd. 2017. Association between red meat consumption and colon cancer: a systematic review of experimental results. Experimental Biology and Medicine 242 (8):813–39. doi: 10.1177/1535370217693117.[Crossref], [Web of Science ®] , [Google Scholar]).

RCTs can play an important role in establishing causal relationships, and generally provide much stronger evidence than that provided by observational data. However, even RCTs are not fail-safe and can also be prone to a range of serious flaws (Krauss, 2018 Krauss, A. 2018. Why all randomised controlled trials produce biased results. Annals of Medicine 50 (4):312–22. doi: 10.1080/07853890.2018.1453233.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]). Intervention studies that overlook the normal dietary context or use non-robust biomarkers should be interpreted with caution, and do not justify claims that there is a clear link between meat and negative health outcomes (see Turner & Lloyd, 2017 Turner, N. D., and S. K. Lloyd. 2017. Association between red meat consumption and colon cancer: a systematic review of experimental results. Experimental Biology and Medicine 242 (8):813–39. doi: 10.1177/1535370217693117.[Crossref], [Web of Science ®] , [Google Scholar]; Kruger & Zhou, 2018 Kruger, C., and Y. Zhou. 2018. Red meat and Colon cancer: a review of mechanistic evidence for heme in the context of risk assessment methodology. Food and Chemical Toxicology 118:131–53. doi: 10.1016/j.fct.2018.04.048.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). The available evidence generally suggests that interventions with red meat do not lead to an elevation of in vivo oxidative stress and inflammation, which are usually cited as being part of the underlying mechanisms triggering chronic diseases (Mann et al., 1997 Mann, N., A. Sinclair, M. Pille, L. Johnson, G. Warrick, E. Reder, and R. Lorenz. 1997. The effect of short-term diets rich in fish, red meat, or white meat on thromboxane and prostacyclin synthesis in humans. Lipids 32 (6):635–44. doi: 10.1007/s11745-997-0081-5.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Hodgson et al., 2007 Hodgson, J. M., N. C. Ward, V. Burke, L. J. Beilin, and I. B. Puddey. 2007. Increased lean red meat intake does not elevate markers of oxidative stress and inflammation in humans. The Journal of Nutrition 137 (2):363–7. doi: 10.1093/jn/137.2.363.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Turner et al., 2017 Turner, K. M., J. B. Keogh, P. J. Meikle, and P. M. Clifton. 2017. Changes in lipids and inflammatory markers after consuming diets high in red meat or dairy for four weeks. Nutrients 9 (8):886. doi: 10.3390/nu9080886.[Crossref], [Web of Science ®] , [Google Scholar]). Even in an epidemiological cohort study that was suggestive of an inflammatory response based on an increased CRP level, this effect became non-significant upon adjustment for obesity (Montonen et al., 2013 Montonen, J., H. Boeing, A. Fritsche, E. Schleicher, H.-G. Joost, M. B. Schulze, A. Steffen, and T. Pischon. 2013. Consumption of red meat and whole-grain bread in relation to biomarkers of obesity, inflammation, glucose metabolism and oxidative stress. European Journal of Nutrition 52 (1):337–45. doi: 10.1007/s00394-012-0340-6.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Moreover, a meta-analysis of RCTs has shown that meat eating does not lead to deterioration of cardiovascular risk markers (O’Connor et al., 2017 O’Connor, L. E., J. E. Kim, and W. W. Campbell. 2017. Total red meat intake of ≥0.5 servings/d does not negatively influence cardiovascular disease risk factors: a systemically searched meta-analysis of randomized controlled trials. The American Journal of Clinical Nutrition 105(1):57–69. doi: 10.3945/ajcn.116.142521.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). The highest category of meat eating even paralleled a potentially beneficial increase in HDL-C level. Whereas plant-based diets indeed seem to lower total cholesterol and LDL-C in intervention studies, they also increase triglyceride levels and decrease HDL-C (Yokoyama et al., 2017 Yokoyama, Y.,. S. M. Levin, and N. D. Barnard. 2017. Association between plant-based diets and plasma lipids: a systematic review and Meta-analysis. Nutrition Reviews 75 (9):683–98. doi: 10.1093/nutrit/nux030.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), which are now often regarded as superior markers of cardiovascular risk (Jeppesen et al., 2001 Jeppesen, J.,. H. Ole Hein, P. Suadicani, and F. Gyntelberg. 2001. Low triglycerides–high high-density lipoprotein cholesterol and risk of ischemic heart disease. Archives of Internal Medicine 161 (3):361–6. doi: 10.1001/archinte.161.3.361.[Crossref], [PubMed] , [Google Scholar]).


(Joey) #10

Many thanks … I’ll dig into it shortly.


(Michael - Don't expect miracles and you won't be disappointed.) #11

3. Meat eating and chronic disease: evaluation of the evidence

3.2. Intervention studies have not been able to indicate unambiguous detrimental effects [2 of 2]

Based on the above, we conclude that there is a lack of robust evidence to confirm an unambiguous mechanistic link between meat eating as part of a healthy diet and the development of Western diseases. It is paramount that the available evidence is graded prior to developing policies and guidelines, making use of quality systems such as GRADE (Grading of Recommendations Assessment, Development and Evaluation; Guyatt et al., 2008 Guyatt, Gordon H., Andrew D. Oxman, Gunn E. Vist, Regina Kunz, Yngve Falck-Ytter, Pablo Alonso-Coello, and Holger J. Schünemann. 2008. GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ 336 (7650):924–6. doi: 10.1136/bmj.39489.470347.AD.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). One of the founders of the GRADE system has issued a public warning that the scientific case against red meat by the IARC panel of the WHO has been overstated, doing “the public a disservice” (Guyatt, 2015 Guyatt, G.H. 2015. A false alarm on red meat and cancer. The Financial Times . https://www.ft.com/content/42259e20-92b5-11e5-bd82-c1fb87bef7af [Google Scholar]). The IARC’s (2015 IARC 2015. IARC Monographs evaluate consumption of red meat and processed meat. Press release n°240, https://www.iarc.fr/en/media-centre/pr/2015/pdfs/pr240_E.pdf [Google Scholar]) claim that red meat is “probably carcinogenic” has never been substantiated. In fact, a risk assessment by Kruger and Zhou (2018 Kruger, C., and Y. Zhou. 2018. Red meat and Colon cancer: a review of mechanistic evidence for heme in the context of risk assessment methodology. Food and Chemical Toxicology 118:131–53. doi: 10.1016/j.fct.2018.04.048.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) concluded that this is not the case. Such hazard classification systems have been heavily criticized, even by one of the members of the IARC working group on red meat and cancer (Klurfeld, 2018). They are accused of being outmoded and leading to avoidable health scares, public funding of unnecessary research and nutritional programs, loss of beneficial foods, and potentially increased health costs (Boyle et al., 2008 Boyle, P., P. Boffetta, and P. Autier. 2008. Diet, nutrition and cancer: public, media and scientific confusion. Annals of Oncology 19 (10):1665–7. doi: 10.1093/annonc/mdn561.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Anonymous, 2016; Boobis et al., 2016 Boobis, Alan R., Samuel M. Cohen, Vicki L. Dellarco, John E. Doe, Penelope A. Fenner-Crisp, Angelo Moretto, Timothy P. Pastoor, Rita S. Schoeny, Jennifer G. Seed, and Douglas C. Wolf. 2016. Classification schemes for carcinogenicity based on hazard-identification have become outmoded and serve neither science nor society. Regulatory Toxicology and Pharmacology 82:158–66. doi: 10.1016/j.yrtph.2016.10.014.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]).


(Michael - Don't expect miracles and you won't be disappointed.) #12

3. Meat eating and chronic disease: evaluation of the evidence

3.3. A scientific assessment should not overlook conflicting data

Dietary advice that identifies meat as an intrinsic cause of chronic diseases often seems to suffer from cherry-picking (Feinman, 2018 Feinman, R. 2018. What’s really wrong with medical research and how to fix it. Journal of Evolution and Health 2 (3):10. doi: 10.15310/2334-3591.1069.[Crossref] , [Google Scholar]). One example of a fact that is typically ignored is that hunter-gatherers are mostly free of cardiometabolic disease although animal products provide the dominant energy source (about two-thirds of caloric intake on average, with some hunter-gatherers obtaining more than 85% of their calories from animal products; Cordain et al., 2000 Cordain, L., J. Brand Miller, S. Boyd Eaton, N. Mann, S. H. A. Holt, and J. D. Speth. 2000. Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. The American Journal of Clinical Nutrition 71 (3):682–92. doi: 10.1093/ajcn/71.3.682.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar], 2002 Cordain, L., S. B. Eaton, J. Brand Miller, N. Mann, and K. Hill. 2002. The paradoxical nature of hunter-gatherer diets: meat-based, yet non-atherogenic. European Journal of Clinical Nutrition 56 (S1):S42–S52. doi: 10.1038/sj.ejcn.1601353.[Crossref], [PubMed] , [Google Scholar]). In comparison, contemporary Americans obtain only about 30% of calories from animal foods (Rehkamp, 2016 Rehkamp, S. 2016. A look at calorie sources in the American diet. Unites States Department of Agriculture, Economic Research Service, https://www.ers.usda.gov/amber-waves/2016/december/a-look-at-calorie-sources-in-the-american-diet. [Google Scholar]).

Whereas per capita consumption of meat has been dropping over the last decades in the US, cardiometabolic diseases such as type-2 diabetes have been rapidly increasing. Although this observation does not resolve the question of causality one way or the other, it should generate some skepticism that meat is the culprit (Feinman, 2018 Feinman, R. 2018. What’s really wrong with medical research and how to fix it. Journal of Evolution and Health 2 (3):10. doi: 10.15310/2334-3591.1069.[Crossref] , [Google Scholar]). Moreover, several studies have found either that meat intake has no association with mortality/morbidity, or that meat restriction is association with various negative health outcomes ( e.g ., Key et al., 2009 Key, T. J., P. N. Appleby, E. A. Spencer, R. C. Travis, A. W. Roddam, and N. E. Allen. 2009. Mortality in british vegetarians: results from the european prospective investigation into cancer and nutrition (EPIC-Oxford). The American Journal of Clinical Nutrition 89 (5):1613S–9S. doi: 10.3945/ajcn.2009.26736L.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Burkert et al., 2014 Burkert, N. T., J. Muckenhuber, F. Großschädl, E. Rásky, and W. Freidl. 2014. Nutrition and health – the association between eating behavior and various health parameters: a matched sample study. PLOS ONE 9 (2):e88278. doi: 10.1371/journal.pone.0088278.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Kwok et al., 2014 Kwok, C. S., S. Umar, P. K. Myint, M. A. Mamas, and Y. K. Loke. 2014. Vegetarian diet, seventh day adventists and risk of cardiovascular mortality: a systematic review and meta-analysis. International Journal of Cardiology 176 (3):680–6. doi: 10.1016/j.ijcard.2014.07.080.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Lippi et al., 2015 Lippi, G., C. Mattiuzzi, and F. Sanchis-Gomar. 2015. Red meat consumption and ischemic heart disease. A systematic literature review. Meat Science 108:32–6. doi: 10.1016/j.meatsci.2015.05.019.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Hur et al., 2018 Hur, S. J., C. Jo, Y. Yoon, J. Y. Jeong, and K. T. Lee. 2018. Controversy on the correlation of red and processed meat consumption with colorectal cancer risk: an asian perspective. Critical Reviews in Food Science and Nutrition . doi: 10.1080/10408398.2018.1495615.[Taylor & Francis Online] , [Google Scholar]; Iguacel et al., 2018 Iguacel, I.,. M. L. Miguel-Berges, A. Gómez-Bruton, L. A. Moreno, and C. Julián. 2018. Veganism, vegetarianism, bone mineral density, and fracture risk: a systematic review and meta-analysis. Nutrition Reviews 77 (1):1–8. doi: 10.1093/nutrit/nuy045.[Crossref], [Web of Science ®] , [Google Scholar]; Yen et al., 2018 Yen, H., W. Q. Li, A. Dhana, T. Li, A. Qureshi, and E. Cho. 2018. Red meat and processed meat intake and risk for cutaneous melanoma in white women and men: two prospective cohort studies. Journal of the American Academy of Dermatology 79 (2):252–7. doi: 10.1016/j.jaad.2018.04.036.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). As another example of conflicting information, the epidemiological association pointing to a potential role of the meat nutrient L-carnitine in atherosclerosis via trimethylamine N-oxide (TMAO) formation (Koeth et al., 2013 Koeth, Robert A., Zeneng Wang, Bruce S. Levison, Jennifer A. Buffa, Elin Org, Brendan T. Sheehy, Earl B. Britt, Xiaoming Fu, Yuping Wu, Lin Li., et al. 2013. Intestinal microbiota metabolism of l-carnitine, a nutrient in red meat, promotes atherosclerosis. Nature Medicine 19 (5):576–85. doi: 10.1038/nm.3145.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), is contradicted by intervention studies (Samulak et al., 2019 Samulak, J. J., A. K. Sawicka, D. Hartmane, S. Grinberga, O. Pugovics, W. Lysiak-Szydlowska, and R. A. Olek. 2019. L-Carnitine supplementation increases trimethylamine-N-oxide but not markers of atherosclerosis in healthy aged women. Annals of Nutrition and Metabolism 74 (1):11–7. doi: 10.1159/000495037.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) and epidemiological data showing that fish intake, being by orders of magnitude the largest supplier of TMAO (Zhang et al., 1999 Zhang, A. Q., S. C. Mitchell, and R. L. Smith. 1999. Dietary precursors of trimethylamine in man: a pilot study. Food and Chemical Toxicology 37 (5):515–20.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), improves triglycerides and HDL levels (Alhassan et al., 2017 Alhassan, A.,. J. Young, M. E. J. Lean, and J. Lara. 2017. Consumption of fish and vascular risk factors: a systematic review and meta-analysis of intervention studies. Atherosclerosis 266:87–94. doi: 10.1016/j.atherosclerosis.2017.09.028.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]).

Although all of the aforementioned studies—particularly the observational ones—clearly have their limitations, they equally deserve to be incorporated in the scientific analysis and health debates.


(Michael - Don't expect miracles and you won't be disappointed.) #13

4. The nutritional benefits of meat

Throughout human history, meat has delivered a wide range of valuable nutrients that are not always easily obtained (or obtainable) from plant materials (Williams, 2007 Williams, P. 2007. Nutritional composition of red meat. Nutrition & Dietetics 64 (s4):S113–S119. doi: 10.1111/j.1747-0080.2007.00197.x.[Crossref] , [Google Scholar]; McAfee et al., 2010 McAfee, A. J., E. M. McSorley, G. J. Cuskelly, B. W. Moss, J. M. Wallace, M. P. Bonham, and A. M. Fearon. 2010. Red meat consumption: an overview of the risks and benefits. Meat Science 84 (1):1–13. doi: 10.1016/j.meatsci.2009.08.029.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Pereira & Vicente, 2013 Pereira, P. M., and A. F. Vicente. 2013. Meat nutritional composition and nutritive role in the human diet. Meat Science 93 (3):586–92. doi: 10.1016/j.meatsci.2012.09.018.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Young et al., 2013 Young, J. F., M. Therkildsen, B. Ekstrand, B. N. Che, M. K. Larsen, N. Oksbjerg, and J. Stagsted. 2013. Novel aspects of health promoting compounds in meat. Meat Science 95 (4):904–11. doi: 10.1016/j.meatsci.2013.04.036.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; McNeill, 2014 McNeill, S. H. 2014. Inclusion of red meat in healthful dietary patterns. Meat Science 98 (3):452–60. doi: 10.1016/j.meatsci.2014.06.028.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Leroy et al., 2018b Leroy, Frédéric, Teresa Aymerich, Marie-Christine Champomier-Vergès, Luca Cocolin, Luc De Vuyst, Mónica Flores, Françoise Leroi, Sabine Leroy, Régine Talon, Rudi F. Vogel., et al. 2018. Fermented meats (and the symptomatic case of the flemish food pyramid): are we heading towards the vilification of a valuable food group?. International Journal of Food Microbiology 274:67–70. doi: 10.1016/j.ijfoodmicro.2018.02.006.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). A major asset of meat is of course its high protein value (Burd et al., 2019 Burd, N. A., J. W. Beals, I. G. Martinez, A. F. Salvador, and S. K. Skinner. 2019. Food-first approach to enhance the regulation of post-exercise skeletal muscle protein synthesis and remodeling. Sports Medicine 49 (S1):59–68. doi: 10.1007/s40279-018-1009-y.[Crossref], [PubMed] , [Google Scholar]), with especially lysine, threonine, and methionine being in short supply in plant-derived diets. It brings in B vitamins (with vitamin B12 being restricted to animal sources only), vitamins A, D, and K2 (particularly via organ meats), and various minerals with iron, zinc, and selenium being of particular importance. Also, the long-chain omega-3 fatty acids EPA and DHA present in animal sources are only poorly obtained in vivo from α-linolenic acid conversion (Cholewski et al., 2018 Cholewski, M., M. Tomczykowa, and M. Tomczyk. 2018. A comprehensive review of chemistry, sources and bioavailability of omega-3 fatty acids. Nutrients 10 (11):1662. doi: 10.3390/nu10111662.[Crossref], [Web of Science ®] , [Google Scholar]), making plants a suboptimal source. Despite being overlooked in most nutritional evaluations, meat also contains various bioactive components as taurine (Laidlaw et al., 1988 Laidlaw, S. A., T. D. Shultz, J. T. Cecchino, and J. D. Kopple. 1988. Plasma and urine taurine levels in vegans. The American Journal of Clinical Nutrition 47 (4):660–3. doi: 10.1093/ajcn/47.4.660.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), creatine (Rae et al., 2003 Rae, C., A. L. Digney, S. R. McEwan, and T. C. Bates. 2003. Oral creatine monohydrate supplementation improves brain performance: a double-blind, placebo-controlled, cross-over trial. Proceedings of the Royal Society B: Biological Sciences 270 (1529):2147–50. doi: 10.1098/rspb.2003.2492.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Benton & Donohoe, 2011 Benton, D., and R. Donohoe. 2011. The influence of creatine supplementation on the cognitive functioning of vegetarians and omnivores. British Journal of Nutrition 105 (7):1100–5. doi: 10.1017/S0007114510004733.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), carnosine (Everaert et al., 2011 Everaert, Inge, Antien Mooyaart, Audrey Baguet, Ana Zutinic, Hans Baelde, Eric Achten, Youri Taes, Emile De Heer, and Wim Derave. 2011. Vegetarianism, female gender and increasing age, but not CNDP1 genotype, are associated with reduced muscle carnosine levels in humans. Amino Acids 40 (4):1221–9. doi: 10.1007/s00726-010-0749-2.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), as well as conjugated linoleic acid, carnitine, choline, ubiquinone, and glutathione (Williams, 2007 Williams, P. 2007. Nutritional composition of red meat. Nutrition & Dietetics 64 (s4):S113–S119. doi: 10.1111/j.1747-0080.2007.00197.x.[Crossref] , [Google Scholar]). These components can offer important nutritional benefits, for instance with respect to the optimal development of cognitive functions.

Sufficient intake of animal products is therefore particularly advisable for population groups with enhanced nutritional needs and is helpful to offer nutritional robustness during various stages of life. As such, it contributes to the physical and cognitive development of infants and children (Neumann et al., 2007 Neumann, C. G., S. P. Murphy, C. Gewa, M. Grillenberger, and N. O. Bwibo. 2007. Meat supplementation improves growth, cognitive, and behavioral outcomes in Kenyan children. The Journal of Nutrition 137 (4):1119–23. doi: 10.1093/jn/137.4.1119.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Hulett et al., 2014 Hulett, J. L., R. E. Weiss, N. O. Bwibo, O. M. Galal, N. Drorbaugh, and C. G. Neumann. 2014. Animal source foods have a positive impact on the primary school test scores of kenyan schoolchildren in a cluster-randomised, controlled feeding intervention trial. British Journal of Nutrition 111 (5):875–86. doi: 10.1017/S0007114513003310.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Tang & Krebs, 2014 Tang, M., and N. F. Krebs. 2014. High protein intake from meats as complementary food increases growth but not adiposity in breastfed infants: a randomized trial. The American Journal of Clinical Nutrition 100 (5):1322–8. doi: 10.3945/ajcn.114.088807.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Cofnas, 2019 Cofnas, N. 2019. Is vegetarianism healthy for children? Critical Reviews in Food Science and Nutrition 59 (13):2052–60. doi: 10.1080/10408398.2018.1437024.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) and prevents deficiencies in young females (Fayet et al., 2014 Fayet, F.,. V. Flood, P. Petocz, and S. Samman. 2014. Avoidance of meat and poultry decreases intakes of omega-3 fatty acids, vitamin B12, selenium and zinc in young women. Journal of Human Nutrition and Dietetics 27:135–42.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Hall et al., 2017 Hall, A. G., T. Ngu, H. T. Nga, P. N. Quyen, P. T. Hong Anh, and J. C. King. 2017. An animal-source food supplement increases micronutrient intakes and iron status among reproductive-age women in rural vietnam. The Journal of Nutrition 147 (6):1200–7. doi: 10.3945/jn.116.241968.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). In the elderly, sufficient meat intake can prevent or improve malnutrition and sarcopenia, also improving health-related quality of life (Pannemans et al., 1998 Pannemans, D. L., A. J. Wagenmakers, K. R. Westerterp, G. Schaafsma, and D. Halliday. 1998. Effect of protein source and quantity on protein metabolism in elderly women. The American Journal of Clinical Nutrition 68 (6):1228–35. doi: 10.1093/ajcn/68.6.1228.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Shibata, 2001 Shibata, H. 2001. Nutritional factors on longevity and quality of life in Japan. Journal of Nutrition, Health and Aging 5 (2):97–102.[PubMed] , [Google Scholar]; Phillips, 2012 Phillips, S. M. 2012. Nutrient-rich meat proteins in offsetting age-related muscle loss. Meat Science 92 (3):174–8. doi: 10.1016/j.meatsci.2012.04.027.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Rondanelli et al., 2015 Rondanelli, M., S. Perna, M. A. Faliva, G. Peroni, V. Infantino, and R. Pozzi. 2015. Novel insights on intake of meat and prevention of sarcopenia: all reasons for an adequate consumption. Nutricion Hospitalaria 32 (5):2136–14. 23. [PubMed], [Web of Science ®] , [Google Scholar]; Torres et al., 2017 Torres, Susan J., Sian Robinson, Liliana Orellana, Stella L. O’Connell, Carley A. Grimes, Niamh L. Mundell, David W. Dunstan, Caryl A. Nowson, and Robin M. Daly. 2017. Effects of progressive resistance training combined with a protein-enriched lean red meat diet on health-related quality of life in elderly women: secondary analysis of a 4-month cluster randomised controlled trial. British Journal of Nutrition 117 (11):1550–9. doi: 10.1017/S0007114517001507.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]).


(Michael - Don't expect miracles and you won't be disappointed.) #14

5. Meat avoidance leads to a loss of nutritional robustness [1 of 3]

Diets poor in animal source foods can lead to various nutritional deficiencies, as already described more than a century ago for the case of pellagra (Morabia, 2008 Morabia, A. 2008. Joseph goldberger’s research on the prevention of pellagra. Journal of the Royal Society of Medicine 101 (11):566–8. doi: 10.1258/jrsm.2008.08k010.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), a condition which remains relevant today for poorly planned vegan diets (Ng & Neff, 2018 Ng, E., and M. Neff. 2018. Recognising the return of nutritional deficiencies: a modern pellagra puzzle. BMJ Case Reports 11 (1):e227454. doi: 10.1136/bcr-2018-227454.[Crossref], [PubMed] , [Google Scholar]). Advocates of vegetarian/vegan diets usually admit that these diets must indeed be “well-planned” in order to be successful, which involves regular supplementation with nutrients such as B12. However, realistically , many people are not diligent about supplementation, and will often dip into deficient or borderline-deficient ranges if they do not obtain nutrients from their regular diet. In such cases, general malnutrition (Ingenbleek & McCully, 2012 Ingenbleek, Y., and K. S. McCully. 2012. Vegetarianism produces subclinical malnutrition, hyperhomocysteinemia and atherogenesis. Nutrition 28 (2):148–53. doi: 10.1016/j.nut.2011.04.009.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), poorer health (Burkert et al., 2014 Burkert, N. T., J. Muckenhuber, F. Großschädl, E. Rásky, and W. Freidl. 2014. Nutrition and health – the association between eating behavior and various health parameters: a matched sample study. PLOS ONE 9 (2):e88278. doi: 10.1371/journal.pone.0088278.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), and nutrient limitations (Kim et al., 2018 Kim, S., M. F. Fenech, and P.-J R. Kim. 2018. Nutritionally recommended food for semi- to strict vegetarian diets based on large-scale nutrient composition data. Scientific Reports 8 (1):4344. doi: 10.1038/s41598-018-22691-1.[Crossref], [PubMed] , [Google Scholar]) may be the result, as found in various countries, such as Denmark (Kristensen et al., 2015 Kristensen, Nadja B., Mia L. Madsen, Tue H. Hansen, Kristine H. Allin, Camilla Hoppe, Sisse Fagt, Mia S. Lausten, Rikke J. Gøbel, Henrik Vestergaard, Torben Hansen., et al. 2015. Intake of macro- and micronutrients in danish vegans. Nutrition Journal 14 (1):115. doi: 10.1186/s12937-015-0103-3.[Crossref], [PubMed] , [Google Scholar]), Finland (Elorinne et al., 2016 Elorinne, Anna-Liisa, Georg Alfthan, Iris Erlund, Hanna Kivimäki, Annukka Paju, Irma Salminen, Ursula Turpeinen, Sari Voutilainen, and Juha Laakso. 2016. Food and nutrient intake and nutritional status of finnish vegans and non-vegetarians. PLOS ONE 11 (2):e0148235. doi: 10.1371/journal.pone.0148235.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), Sweden (Larsson & Johansson, 2002 Larsson, C. L., and G. K. Johansson. 2002. Dietary intake and nutritional status of young vegans and omnivores in Sweden. The American Journal of Clinical Nutrition 76 (1):100–6. doi: 10.1093/ajcn/76.1.100.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), and Switzerland (Schüpbach et al., 2017 Schüpbach, R., R. Wegmüller, C. Berguerand, M. Bui, and I. Herter-Aeberli. 2017. Micronutrient status and intake in omnivores, vegetarians and vegans in Switzerland. European Journal of Nutrition 56 (1):283–93. doi: 10.1007/s00394-015-1079-7.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). For example, a substantial number of vegetarians and vegans are in the deficient or borderline-deficient range for B12 (Herrmann & Geisel, 2002 Herrmann, W., and J. Geisel. 2002. 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(Michael - Don't expect miracles and you won't be disappointed.) #15

5. Meat avoidance leads to a loss of nutritional robustness [2 of 3]

Other potentially challenging micronutrients for people on plant-based diets include (but are not limited to) iodine (Krajcovicová-Kudlácková et al., 2008 Krajcovicová-Kudlácková, M., K. Bucková, I. Klimes, and E. Seboková. 2008. Iodine deficiency in vegetarians and vegans. Annals of Nutrition and Metabolism 47:183–5.[Crossref] , [Google Scholar]; Leung et al., 2011 Leung, A. M., A. Lamar, X. He, L. E. Braverman, and E. N. Pearce. 2011. Iodine status and thyroid function of boston-area vegetarians and vegans. The Journal of Clinical Endocrinology & Metabolism 96 (8):e1303–7. doi: 10.1210/jc.2011-0256.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Brantsaeter et al., 2018 Brantsaeter, Anne, Helle Knutsen, Nina Johansen, Kristine Nyheim, Iris Erlund, Helle Meltzer, and Sigrun Henjum. 2018. Inadequate iodine intake in population groups defined by age, life stage and vegetarian dietary practice in a norwegian convenience sample. Nutrients 10 (2):230. doi: 10.3390/nu10020230.[Crossref], [Web of Science ®] , [Google Scholar]), iron (Wilson & Ball, 1999 Wilson, A. K., and M. J. Ball. 1999. Nutrient intake and iron status of australian male vegetarians. European Journal of Clinical Nutrition 53 (3):189–94. doi: 10.1038/sj.ejcn.1600696.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Wongprachum et al., 2012 Wongprachum, K., K. Sanchaisuriya, P. Sanchaisuriya, S. Siridamrongvattana, S. Manpeun, and F. P. Schlep. 2012. Proxy indicators for identifying iron deficiency among anemic vegetarians in an area prevalent for thalassemia and hemoglobinopathies. Acta Haematologica 127 (4):250–5. doi: 10.1159/000337032.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Awidi et al., 2018 Awidi, M., H. Bawaneh, H. Zureigat, M. AlHusban, and A. Awidi. 2018. Contributing factors to iron deficiency anemia in women in Jordan: a single-center cross-sectional study. PLOS ONE 13 (11):e0205868. doi: 10.1371/journal.pone.0205868.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), selenium (Schultz & Leklem, 1983 Schultz, T. D., and J. E. Leklem. 1983. Selenium status of vegetarians, nonvegetarians, and hormone-dependent cancer subjects. The American Journal of Clinical Nutrition 37:114–8. doi: 10.1093/ajcn/37.1.114.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Kadrabová et al., 1995 Kadrabová, J., A. Madaric, Z. Kováciková, and E. Ginter. 1995. Selenium status, plasma zinc, copper, and magnesium in vegetarians. Biological Trace Element Research 50 (1):13–24. doi: 10.1007/BF02789145.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), and zinc (Foster et al., 2013 Foster, M., A. Chu, P. Petocz, and S. Samman. 2013. Effect of vegetarian diets on zinc status: a systematic review and meta-analysis of studies in humans. Journal of the Science of Food and Agriculture 93 (10):2362–71. doi: 10.1002/jsfa.6179.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Even if plant-based diets contain alpha linolenic acid, this may not (as noted) prevent deficiencies in the long-chain omega-3 fatty acids EPA and DHA (Rosell et al., 2005 Rosell, M. S., Z. Lloyd-Wright, P. N. Appleby, T. A. Sanders, N. E. Allen, and T. J. Key. 2005. Long-chain n-3 polyunsaturated fatty acids in plasma in british meat-eating, vegetarian, and vegan men. The American Journal of Clinical Nutrition 82 (2):327–34. doi: 10.1093/ajcn.82.2.327.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), which can pose serious risks in pregnancy and for growing children (Burdge et al., 2017 Burdge, G. C., S.-Y. Tan, and C. J. Henry. 2017. Long-chain n-3 PUFA in vegetarian women: a metabolic perspective. Journal of Nutritional Science 6:e58. doi: 10.1017/jns.2017.62.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Cofnas, 2019 Cofnas, N. 2019. Is vegetarianism healthy for children? Critical Reviews in Food Science and Nutrition 59 (13):2052–60. doi: 10.1080/10408398.2018.1437024.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]).


(Michael - Don't expect miracles and you won't be disappointed.) #16

5. Meat avoidance leads to a loss of nutritional robustness [3 of 3]

Risks of nutritional deficiency are also documented by an extensive list of clinical case reports in the medical literature, with serious and sometimes irreversible pathological symptoms being reported for infants ( e.g ., Shinwell & Gorodisher, 1982 Shinwell, E. D., and R. Gorodischer. 1982. Totally vegetarian diets and infant nutrition. Pediatrics 70 (4):582–6.[PubMed], [Web of Science ®] , [Google Scholar]; Zengin et al., 2009 Zengin, E., N. Sarper, and S. Caki Kiliç. 2009. Clinical manifestations of infants with nutritional vitamin B deficiency due to maternal dietary deficiency. Acta Paediatrica 98 (1):98–102. doi: 10.1111/j.1651-2227.2008.01059.x.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Guez et al., 2012 Guez, S., G. Chiarelli, F. Menni, S. Salera, N. Principi, and S. Esposito. 2012. Severe vitamin B12 deficiency in an exclusively breastfed 5-month-old italian infant born to a mother receiving multivitamin supplementation during pregnancy. BMC Pediatrics 12 (1):85. doi: 10.1186/1471-2431-12-85.[Crossref], [PubMed] , [Google Scholar]; Bravo et al., 2014 Bravo, J. P., C. J. Ibarra, and M. M. Paredes. 2014. Hematological and neurological compromise due to vitamin B12 deficit in infant of a vegetarian mother: case report. Revista Chilena de Pediatría 85:337–43.[PubMed] , [Google Scholar]; Kocaoglu et al., 2014 Kocaoglu, C., F. Akin, H. Caksen, S. B. Böke, S. Arslan, and S. Aygün. 2014. Cerebral atrophy in a vitamin B12-deficient infant of a vegetarian mother. Journal of Health, Population and Nutrition 32(2):367–71.[PubMed], [Web of Science ®] , [Google Scholar]; Goraya et al., 2015 Goraya, J. S., S. Kaur, and B. Mehra. 2015. Neurology of nutritional vitamin B12 deficiency in infants: case series from India and literature review. Journal of Child Neurology 30 (13):1831–7. doi: 10.1177/0883073815583688.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), children ( e.g ., Colev et al., 2004 Colev, M., H. Engel, M. Mayers, M. Markowitz, and L. Cahill. 2004. Vegan diet and vitamin a deficiency. Clinical Pediatrics 43 (1):107–9. doi: 10.1177/000992280404300116.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Crawford & Say, 2013 Crawford, J. R., and D. Say. 2013. Vitamin B12 deficiency presenting as acute ataxia. Case Reports 2013:bcr2013008840.[PubMed] , [Google Scholar]), adolescents ( e.g ., Chiron et al., 2001 Chiron, R., A. Dabadie, V. Gandemer-Delignieres, M. Balençon, E. Legall, and M. Roussey. 2001. Anemia and limping in a vegetarian adolescent. Archives de Pédiatrie 8 (1):62–5. doi: 10.1016/S0929-693X(00)00168-8.[Crossref], [PubMed] , [Google Scholar]; Licht et al., 2001 Licht, D. J., G. T. Berry, D. G. Brooks, and D. P. Younkin. 2001. Reversible subacute combined degeneration of the spinal cord in a 14-year-old due to a strict vegan diet. Clinical Pediatrics 40 (7):413–5. doi: 10.1177/000992280104000710.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; O’Gorman et al., 2002 O’Gorman, P., D. Holmes, A. V. Ramanan, B. Bose-Haider, M. J. Lewis, and A. Will. 2002. Dietary vitamin B12 deficiency in an adolescent white boy. Journal of Clinical Pathology 55(6):475–6. doi: 10.1136/jcp.55.6.475.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), and adults ( e.g ., Milea et al., 2000 Milea, D., N. Cassoux, and P. LeHoang. 2000. Blindness in a strict vegan. The New England Journal of Medicine 342 (12):897–8. doi: 10.1056/NEJM200003233421217.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Brocadello et al., 2007 Brocadello, F., G. Levedianos, F. Piccione, R. Manara, and F. F. Pesenti. 2007. Irreversible subacute sclerotic combined degeneration of the spinal cord in a vegan subject. Nutrition 23 (7-8):622–4. doi: 10.1016/j.nut.2007.05.006.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; De Rosa et al., 2012 De Rosa, Anna, Fabiana Rossi, Maria Lieto, Roberto Bruno, Amalia De Renzo, Vincenzo Palma, Mario Quarantelli, and Giuseppe De Michele. 2012. Subacute combined degeneration of the spinal cord in a vegan. Clinical Neurology and Neurosurgery 114 (7):1000–2. doi: 10.1016/j.clineuro.2012.01.008.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Førland & Lindberg, 2015 Førland, E. S., and M. J. Lindberg. 2015. Severe macrocytic anaemia and secondary hyperparathyroidism in a vegan. Ugeskriftet Laeger 177:V02150167.[PubMed] , [Google Scholar]). The latter reports commonly refer to failure to thrive, hyperparathyroidism, macrocytic anemia, optic and other neuropathies, lethargy, degeneration of the spinal cord, cerebral atrophy, and other serious conditions. Although the direction of causality is not clear, meat avoidance is statistically associated with eating disorders and depression (Zhang et al., 2017 Zhang, Y., Y. Yang, M. S. Xie, X. Ding, H. Li, Z. C. Liu, and S. F. Peng. 2017. Is meat consumption associated with depression? a Meta-analysis of observational studies. BMC Psychiatry 17 (1):409. doi: 10.1186/s12888-017-1540-7.[Crossref], [PubMed] , [Google Scholar]; Barthels et al., 2018 Barthels, F., F. Meyer, and R. Pietrowsky. 2018. Orthorexic and restrained eating behaviour in vegans, vegetarians, and individuals on a diet. Eating and Weight Disorders - Studies on Anorexia , Bulimia and Obesity 23 (2):159–66. doi: 10.1007/s40519-018-0479-0.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Hibbeln et al., 2018 Hibbeln, J. R., K. Northstone, J. Evans, and J. Golding. 2018. Vegetarian diets and depressive symptoms among men. Journal of Affective Disorders 225:13–7. doi: 10.1016/j.jad.2017.07.051.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Matta et al., 2018 Matta, Joane, Sébastien Czernichow, Emmanuelle Kesse-Guyot, Nicolas Hoertel, Frédéric Limosin, Marcel Goldberg, Marie Zins, and Cedric Lemogne. 2018. Depressive symptoms and vegetarian diets: results from the constances cohort. Nutrients 10 (11):1695. doi: 10.3390/nu10111695.[Crossref], [Web of Science ®] , [Google Scholar]; Nezlek et al., 2018 Nezlek, J. B., C. A. Forestell, and D. B. Newman. 2018. Relationships between vegetarian dietary habits and daily well-being. Ecology of Food and Nutrition 57 (5):425–38. doi: 10.1080/03670244.2018.1536657.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) and may mirror neurological problems (Kapoor et al., 2017 Kapoor, A., M. Baig, S. A. Tunio, A. S. Memon, and H. Karmani. 2017. Neuropsychiatric and neurological problems among vitamin B12 deficient young vegetarians. Neurosciences 22 (3):228–32. doi: 10.17712/nsj.2017.3.20160445.[Crossref], [Web of Science ®] , [Google Scholar]).

Our main concern is that avoiding or minimizing meat consumption too strictly may compromise the delivery of nutrients, especially in children and other vulnerable populations. Evidently, health effects of plant-based approaches depend largely on the dietary composition (Satija et al., 2016 Satija, Ambika, Shilpa N. Bhupathiraju, Eric B. Rimm, Donna Spiegelman, Stephanie E. Chiuve, Lea Borgi, Walter C. Willett, JoAnn E. Manson, Qi Sun, Frank B. Hu., et al. 2016. Plant-based dietary patterns and incidence of type 2 diabetes in US men and women: results from three prospective cohort studies. PLOS Medicine 13 (6):e1002039. doi: 10.1371/journal.pmed.1002039.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Yet, the more restricted the diet and the younger the age, the more this will be a point of attention (Van Winckel et al., 2011 Van Winckel, M., S. Vande Velde, R. De Bruyne, and S. Van Biervliet. 2011. Clinical practice: vegetarian infant and child nutrition. European Journal of Pediatrics 170 (12):1489–94. doi: 10.1007/s00431-011-1547-x.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). According to Cofnas (2019 Cofnas, N. 2019. Is vegetarianism healthy for children? Critical Reviews in Food Science and Nutrition 59 (13):2052–60. doi: 10.1080/10408398.2018.1437024.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]), however, even realistic vegetarian diets that include diligent supplementation can put children at risk for deficiencies and thereby compromise health in both the short and long term. There is some direct and indirect evidence that the elevated phytoestrogen intake associated with low-meat diets may pose risks for the development of the brain and reproductive system (Cofnas, 2019 Cofnas, N. 2019. Is vegetarianism healthy for children? Critical Reviews in Food Science and Nutrition 59 (13):2052–60. doi: 10.1080/10408398.2018.1437024.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]). Moreover, attempts to introduce dietary modifications that are also compatible with vegan philosophy often pose a medicosocial challenge (Shinwell & Gorodischer, 1982 Shinwell, E. D., and R. Gorodischer. 1982. Totally vegetarian diets and infant nutrition. Pediatrics 70 (4):582–6.[PubMed], [Web of Science ®] , [Google Scholar]). In our opinion, the official endorsement of diets that avoid animal products as healthy options is posing a risk that policy makers should not be taking. As stated by Giannini et al. (2006 Giannini, A., N. Mirra, and M. F. Patria. 2006. Health risks for children raised on vegan or vegetarian diets. Pediatric Critical Care Medicine 7 (2):188. doi: 10.1097/01.PCC.0000200965.44972.8F.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]): “It is alarming in a developed country to find situations in which a child’s health is put at risk by malnutrition, not through economic problems but because of the ideological choices of the parents”.


(Michael - Don't expect miracles and you won't be disappointed.) #17

6. Conclusions

Although meat has been a central component of the diet of our lineage for millions of years, some nutrition authorities—who often have close connections to animal rights activists or other forms of ideological vegetarianism, such as Seventh-Day Adventism (Banta et al., 2018 Banta, J. E., J. W. Lee, G. Hodgkin, Z. Yi, A. Fanica, and J. Sabate. 2018. The global influence of the Seventh-day Adventist Church on diet. Religions 9 (9):251. doi: 10.3390/rel9090251.[Crossref], [Web of Science ®] , [Google Scholar])—are promoting the view that meat causes a host of health problems and has no redeeming value. We contend that a large part of the case against meat is based on cherry-picked evidence and low-quality observational studies. The bald claim that red meat is an “unhealthy food” (Willett et al., 2019 Willett, Walter, Johan Rockström, Brent Loken, Marco Springmann, Tim Lang, Sonja Vermeulen, Tara Garnett, David Tilman, Fabrice DeClerck, Amanda Wood., et al. 2019. Food in the anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet 393 (10170):447–92. doi: 10.1016/S0140-6736(18)31788-4.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) is wildly unsupported.

Based on misrepresentations of the state of the science, some organizations are attempting to influence policy makers to take action to reduce meat consumption. Simplification of complex science increases persuasive power but may also serve ideological purposes and lead to scientistic approaches. According to Mayes and Thompson (2015 Mayes, C. R., and D. B. Thompson. 2015. What should we eat? biopolitics, ethics, and nutritional scientism. Journal of Bioethical Inquiry 12 (4):587–99. doi: 10.1007/s11673-015-9670-4.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), manifestations of nutritional scientism in the context of biopolitics can have various ethical implications for “individual responsibility and freedom, concerning iatrogenic harm, and for well-being”. Well-meaning yet overemphasized and premature recommendations may eventually cause more damage than benefit, not only physiologically but also by unjustifiably holding individuals accountable for their health outcomes. We believe that a large reduction in meat consumption, such as has been advocated by the EAT-Lancet Commission (Willett et al., 2019 Willett, Walter, Johan Rockström, Brent Loken, Marco Springmann, Tim Lang, Sonja Vermeulen, Tara Garnett, David Tilman, Fabrice DeClerck, Amanda Wood., et al. 2019. Food in the anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet 393 (10170):447–92. doi: 10.1016/S0140-6736(18)31788-4.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), could produce serious harm. Meat has long been, and continues to be, a primary source of high-quality nutrition. The theory that it can be replaced with legumes and supplements is mere speculation. While diets high in meat have proved successful over the long history of our species, the benefits of vegetarian diets are far from being established, and its dangers have been largely ignored by those who have endorsed it prematurely on the basis of questionable evidence.

Acknowledgements

FL acknowledges financial support of the Research Council of the Vrije Universiteit Brussel, including the SRP7 and IOF342 projects, and in particular the Interdisciplinary Research Program ‘Tradition and naturalness of animal products within a societal context of change’ (IRP11).


(Michael - Don't expect miracles and you won't be disappointed.) #18

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