15 Reasons to Rethink Red Meat

rethink-red-meatWho doesn’t love a grilled steak, washed down with red wine? Um, potentially your microbiome, the aggregate microbes that live in your gut and play a major role in your risk of disease such as obesity, cancer, and diabetes.1Turnbaugh, P., J. et al. “An obesity-associated gut microbiome with increased capacity for energy harvest.” Nature 444, no. 7122 ...continue In fact, grilled meat may be the most harmful of all.2Berjia, F., L. et al. “Burden of diseases estimates associated to different red meat cooking practices.” Food and Chemical ...continue

I’m often asked, especially by my friends in the Paleo community, why I recommend that people remove red meat for 21 days in my book, The Hormone Reset Diet. Here are 15 reasons, along with the scientific evidence. Most link a diet high in red meat with altered microbiome, and as a result, wayward molecular relationships inside your own cells.

  1. Meat consumption raises your estrogen.3Harmon, B., E. et al. “Oestrogen levels in serum and urine of premenopausal women eating low and high amounts of meat.” Public Health ...continue Eating meat can aggravate estrogen dominance. Indeed, women with endometriosis consume more red meat, and eat less fish and vegetables.4Parazzini, F. et al. “Diet and endometriosis risk: a literature review.” Reproductive Biomedicine Online 26, no. 4 (2013): 323-336. Overall, more meat consumption is associated with less fiber consumption, which raises bad estrogens5Aubertin-Leheudre, M. et al. “Fat/fiber intakes and sex hormones in healthy premenopausal women in USA.” The Journal of Steroid ...continue and grows the wrong bacteria in your microbiome. 6Adlercreutz, H., et al. “Studies on the role of intestinal bacteria in metabolism of synthetic and natural steroid hormones.” Journal of ...continue
  1. Women who eat red meat have a greater risk of breast cancer, and eating more fish is protective.  7Rossi, R., E. et al. “The Role of Dietary Factors in Prevention and Progression of Breast Cancer.” Anticancer Research 34, no. 12 ...continue The association is greatest in postmenopausal women, with an increased risk of 22% among those who eat red and/or processed meat. 8Alexander, D., D. et al. “A review and meta-analysis of red and processed meat consumption and breast cancer.” Nutrition Research ...continue Smaller studies show the risk is greatest with processed meat. 9Mourouti, N. et al. “Meat consumption and breast cancer: A case–control study in women.” Meat Science 100 (2015): 195-201. Other studies suggest fried meat is the problem.10Larsson, S. et al. “Long-term meat intake and risk of breast cancer by oestrogen and progesterone receptor status in a cohort of Swedish ...continue
  1. High red meat consumption increases your risk of colorectal cancer.11Hagland, H. et al. “Cellular metabolism in colorectal carcinogenesis: influence of lifestyle, gut microbiome and metabolic pathways.” ...continue
    The mechanism is most likely an altered microbiome.12Feng, Q. et al. “Gut microbiome development along the colorectal adenoma–carcinoma sequence.” Nature Communications 6 (2015); ...continue
    In fact, the alterations in the gut microbiome can be used to screen for colorectal cancer.13Zackular, J. et al. “The human gut microbiome as a screening tool for colorectal cancer.” Cancer Prevention Research 7, no. 11 (2014): ...continue
  1. Red meat may increase your risk of cancer through preservation methods (N-nitroso compounds), high-temperature cooking methods (heterocyclic amines and polycyclic aromatic hydrocarbons), and mycotoxins (including sporidesmin and dothistromin).14Ferguson, L., R. et al. “Natural and human-made mutagens and carcinogens in the human diet.” Toxicology 181 (2002): 79-82; Alaejos, M. ...continue
  1. Women with the PPARG gene variant like me lose weight when they eat more fish (omega-3 fats) as opposed to red meat (saturated fats). This link has not been studied in men.15Memisoglu A. et al. “Interaction between a peroxisome proliferator-activated receptor gamma gene polymorphism and dietary fat intake in relation to ...continue
  1. Factory-farmed meats gut-microbiomeare high in certain endocrine disruptors and persistent organic pollutants (POPs). Meat, pork, and dairy expose you to multiple endocrine disruptors, including phthalates, HBCD, PBDEs, and Deca-BDEs.16Schecter, A. et al. “Polybrominated diphenyl ethers (PBDEs) and hexabromocyclodecane (HBCD) in composite US food samples.” Environmental ...continue Persistent Organic Pollutants (POPs) are linked to lower adiponectin levels, 17Lim, J. et al. “Association between serum levels of adiponectin and polychlorinated biphenyls in Korean men and women.” ...continue diabetes, 18Magliano, D. J. et al. “Persistent organic pollutants and diabetes: A review of the epidemiological evidence.” Diabetes & ...continue breast, and prostate cancer. 26Lim, J., E. “Body concentrations of persistent organic pollutants and prostate cancer: a meta-analysis.” Environmental Science and Pollution ...continue Not surprisingly, POPs exposure shifts the microbiome in the wrong direction.19Zhang, L. et al. “Persistent Organic Pollutants Modify Gut Microbiota–Host Metabolic Homeostasis in Mice Through Aryl Hydrocarbon Receptor ...continue
  1. The Japanese have the lowest rates in the world of estrogen-related cancer such as breast and prostate. Their diet is rich in fish oil and low in red meat.20Tsugane, S. et al. “The JPHC study: design and some findings on the typical Japanese diet.” Japanese Journal of Clinical Oncology 44, ...continue
  1. Red meat is associated with an increased risk of diabetes. This doesn’t prove causality, but signifies concern.
  1. Red meat increases uric acid and creatinine. 21Foerster, J. et al. “The Influence of Whole Grain Products and Red Meat on Intestinal Microbiota Composition in Normal Weight Adults: A ...continue This increases risk of gout and kidney problems.
  1. Red meat increases hs-CRP, a marker of inflammation, and GGT, a marker of liver damage.22Montonen, J. et al. “Consumption of red meat and whole-grain bread in relation to biomarkers of obesity, inflammation, glucose metabolism and ...continue
  1. The fastest way to fatten an animal is to feed it grain. By extension, the fastest way to fatten a human is to feed him or her grain-fed meat.
  1. Meat is contaminated with superbugs, including 55% of ground beef sampled by the Environmental Working Group.23Superbugs Invade American Supermarkets, Environmental Working Group, accessed March 26, 2015, http://www.ewg.org/meateatersguide/superbugs/.
  1. Red meat consumption is rising fast in the US and worldwide, and contributes significantly to the rise of greenhouse gases and water shortages. You probably know that one pound of red meat requires 2,500 gallons of water versus 23 gallons of water to produce a pound of lettuce.
  1. Even grass-fed meat can be problematic. There are no data as of this writing to show that grass-fed meat is better for your estrogen levels. An animal is considered grass-fed, according to the USDA Grass Fed Marketingcow-eating-hay Claim Standards, when grass and forage are the “feed source consumed for the lifetime of the ruminant animal, with the exception of milk consumed prior to weaning. Animals cannot be fed grain or grain by-products and must have continuous access to pasture during the growing season. Hay, haylage, baleage, silage, crop residue without grain, and other roughage sources may also be included as acceptable feed sources. Routine mineral and vitamin supplementation may also be included in the feeding regimen.” 24Grass Fed Marketing Claim Standards, USDA Agricultural Marketing Service, October 16, 2007, ...continue So, grass-fed cows can still eat silage and baleage (whatever that means), and crop residue? And what exactly is in crop residue? You get my point. Grass fed may not be what you think it is.
  1. Cooking reduces but does not eliminate the potential for exposure to growth promoters in ground beef. 25Braekevelt, E. et al. “Effect of Cooking on Concentrations of β-Estradiol and Metabolites in Model Matrices and Beef.” Journal of ...continue

To be fair, grass-fed meat contains a better ratio of omega-6 to omega-3 fats, but data are lacking to show that grass-fed meat is better for your estrogen levels, risk of cancer, and weight gain. In the absence of robust data, I recommend taking a periodic break from red meat and see how your body responds. Because of my PPARG gene, I lose weight when I substitute fish for red meat — maybe you do too.

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References   [ + ]

1. Turnbaugh, P., J. et al. “An obesity-associated gut microbiome with increased capacity for energy harvest.” Nature 444, no. 7122 (2006): 1027-131.
2. Berjia, F., L. et al. “Burden of diseases estimates associated to different red meat cooking practices.” Food and Chemical Toxicology 66 (2014): 237-244.
3. Harmon, B., E. et al. “Oestrogen levels in serum and urine of premenopausal women eating low and high amounts of meat.” Public Health Nutrition 17, no. 09 (2014): 2087-2093; Fung, T. et al. “A dietary pattern derived to correlate with estrogens and risk of postmenopausal breast cancer.” Breast cancer research and treatment132, no. 3 (2012): 1157-1162; Aubertin-Leheudre, M. et al. “Diets and hormonal levels in postmenopausal women with or without breast cancer.” Nutrition and Cancer 63, no. 4 (2011): 514-524.
4. Parazzini, F. et al. “Diet and endometriosis risk: a literature review.” Reproductive Biomedicine Online 26, no. 4 (2013): 323-336.
5. Aubertin-Leheudre, M. et al. “Fat/fiber intakes and sex hormones in healthy premenopausal women in USA.” The Journal of Steroid Biochemistry and Molecular Biology 112, no. 1 (2008): 32-39.
6. Adlercreutz, H., et al. “Studies on the role of intestinal bacteria in metabolism of synthetic and natural steroid hormones.” Journal of Steroid Biochemistry 20, no. 1 (1984): 217-229.
7. Rossi, R., E. et al. “The Role of Dietary Factors in Prevention and Progression of Breast Cancer.” Anticancer Research 34, no. 12 (2014): 6861-6875.
8. Alexander, D., D. et al. “A review and meta-analysis of red and processed meat consumption and breast cancer.” Nutrition Research Reviews 23, no. 02 (2010): 349-365.
9. Mourouti, N. et al. “Meat consumption and breast cancer: A case–control study in women.” Meat Science 100 (2015): 195-201.
10. Larsson, S. et al. “Long-term meat intake and risk of breast cancer by oestrogen and progesterone receptor status in a cohort of Swedish women.” European Journal of Cancer 45, no. 17 (2009): 3042-3046.
11. Hagland, H. et al. “Cellular metabolism in colorectal carcinogenesis: influence of lifestyle, gut microbiome and metabolic pathways.” Cancer Letters 356, no. 2 (2015): 273-280; Thompson, P., A. “Navigating the Maize between Red Meat and Oncomirs.” Cancer Prevention Research 7, no. 8 (2014): 777-780.
12. Feng, Q. et al. “Gut microbiome development along the colorectal adenoma–carcinoma sequence.” Nature Communications 6 (2015); Hagland, H. et al. “Cellular metabolism in colorectal carcinogenesis: influence of lifestyle, gut microbiome and metabolic pathways.” Cancer Letters 356, no. 2 (2015): 273-280.
13. Zackular, J. et al. “The human gut microbiome as a screening tool for colorectal cancer.” Cancer Prevention Research 7, no. 11 (2014): 1112-1121.
14. Ferguson, L., R. et al. “Natural and human-made mutagens and carcinogens in the human diet.” Toxicology 181 (2002): 79-82; Alaejos, M. et al. “Exposure to heterocyclic aromatic amines from the consumption of cooked red meat and its effect on human cancer risk: a review.” Food Additives and Contaminants 25, no. 1 (2008): 2-24.
15. Memisoglu A. et al. “Interaction between a peroxisome proliferator-activated receptor gamma gene polymorphism and dietary fat intake in relation to body mass.” Human Molecular Genetics 12 (22) (2003): 2923-9.
16. Schecter, A. et al. “Polybrominated diphenyl ethers (PBDEs) and hexabromocyclodecane (HBCD) in composite US food samples.” Environmental Health Perspectives (Online) 118, no. 3 (2010): 357.
17. Lim, J. et al. “Association between serum levels of adiponectin and polychlorinated biphenyls in Korean men and women.” Endocrine (2014): 1-7.) obesity,((Donat-Vargas, C. et al. “Association between dietary intakes of PCBs and the risk of obesity: the SUN project.” Journal of Epidemiology and Community Health 68, no. 9 (2014): 834-841.diabetes
18. Magliano, D. J. et al. “Persistent organic pollutants and diabetes: A review of the epidemiological evidence.” Diabetes & Metabolism 40, no. 1 (2014): 1-14; Taylor, K,. W. et al. “Evaluation of the association between persistent organic pollutants (POPs) and diabetes in epidemiological studies: a national toxicology program workshop review.” Environmental Health Perspectives 121, no. 7 (2013): 774-783; Lee, D., H. et al. “Association between serum concentrations of persistent organic pollutants and insulin resistance among nondiabetic adults Results from the National Health and Nutrition Examination Survey 1999–2002.” Diabetes Care 30, no. 3 (2007): 622-628; Kim, K., S. et al. “Interaction between persistent organic pollutants and C-reactive protein in estimating insulin resistance among non-diabetic adults.” Journal of Preventive Medicine and Public Health 45, no. 2 (2012): 62-69.
19. Zhang, L. et al. “Persistent Organic Pollutants Modify Gut Microbiota–Host Metabolic Homeostasis in Mice Through Aryl Hydrocarbon Receptor Activation.” Environmental Health Perspectives (2015).
20. Tsugane, S. et al. “The JPHC study: design and some findings on the typical Japanese diet.” Japanese Journal of Clinical Oncology 44, no. 9 (2014): 777-782.
21. Foerster, J. et al. “The Influence of Whole Grain Products and Red Meat on Intestinal Microbiota Composition in Normal Weight Adults: A Randomized Crossover Intervention Trial.” PloS One 9, no. 10 (2014): e109606.
22. Montonen, J. et al. “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, no. 1 (2013): 337-345.
23. Superbugs Invade American Supermarkets, Environmental Working Group, accessed March 26, 2015, http://www.ewg.org/meateatersguide/superbugs/.
24. Grass Fed Marketing Claim Standards, USDA Agricultural Marketing Service, October 16, 2007, http://www.ams.usda.gov/AMSv1.0/ams.fetchTemplateData.dotemplate=TemplateN&rightNav1=GrassFedMarketingClaimStandards&topNav=&leftNav=GradingCertificationandVerfication&page=GrassFedMarketingClaims&resultType=
25. Braekevelt, E. et al. “Effect of Cooking on Concentrations of β-Estradiol and Metabolites in Model Matrices and Beef.” Journal of Agricultural and Food Chemistry 59, no. 3 (2011): 915-920.
26. Lim, J., E. “Body concentrations of persistent organic pollutants and prostate cancer: a meta-analysis.” Environmental Science and Pollution Research International (2015).
Sara Gottfried MD About Sara Gottfried MD

Sara Gottfried, MD is the author of the new book, Younger: A Breakthrough Program to Reset Your Genes, Reverse Aging, and Turn Back the Clock 10 Years. She's the two-time New York Times bestselling author of The Hormone Cure and The Hormone Reset Diet. After graduating from Harvard Medical School and MIT, Dr. Gottfried completed her residency at the University of California at San Francisco. She is a board-certified gynecologist who teaches natural hormone balancing in her novel online programs so that women can lose weight, detoxify, and slow down aging. Dr. Gottfried lives in Berkeley, CA with her husband and two daughters.