Dr. Fuhrman's NEW G-BOMBS Bars and Limited Edition Peppermint Chocolate Pop'Ems Are Now Available!

Animal products, the microbiome, and heart disease


STOP before you eat RED MEAT: It may lead to disease

Although steaks, hamburgers and all matter of red meat are popular menu fare, studies reveal red meat intake is associated with an elevated risk of cardiovascular disease and cardiovascular death.1-5 Just as smoking cigarettes was once popular but is now shunned, so should be the case with eating red meat. Scientific research continues to show consuming red meat may have profound damaging effects on overall health and longevity. It is vitally important red meat should be replaced (or at least greatly limited) in our diet with foods proven to be good for us.

Combined data from the Nurses’ Health Study and Health Professionals Follow-up study, comprising over 120,000 people, estimated that each daily serving (100 grams--which is equal to 3.5 ounces or ¼ pound of a T-bone steak) of red meat raises the risk of cardiovascular death by 18 percent. Conversely,  replacing one daily serving of red meat with one daily serving of nuts was associated with a 30 percent reduction in risk of coronary heart disease.2  In other long-term studies, higher animal protein intake was also linked to a greater risk of death from all causes.6 

Two factors thought to link red meat to increased cardiovascular disease risk are the high saturated fat and heme iron contents of red meat. High saturated fat is known to elevate total and LDL cholesterol levels, and excess iron is associated with oxidative stress, which promotes atherosclerosis.7-10 However,  scientists theorize that additional properties of red meat are likely involved.3

Red meat and eggs impact the type of bacteria in our digestive tracts.

Recent research has discovered another mechanism by which red meat (as well as eggs) may increase cardiovascular risk – by modulating the species of bacteria that populate our digestive tract.

Importantly, what we eat determines which species of bacteria thrive in our digestive tract. Healthful, fiber-rich foods feed healthy gut bacteria, whereas high red meat and egg intake may promote unhealthy gut bacteria.  The gut microbiome (a community of bacteria) interacts with the cells of the intestinal wall to exert profound effects on our health. Beneficial microbes produce vitamins, protect us against disease-causing microbes, promote healthy immune function, facilitate energy extraction from food, and break down fiber and resistant starch into beneficial short chain fatty acids, which protect us against colon cancer.11,12 Healthful, fiber-rich plant foods provide an energy source (“prebiotics”) for beneficial bacteria to grow.13,14

Carnitine is derived from the amino acid lysine and involved in energy production, and it is abundant in animal products, especially red meat. It is found in all cells in our bodies, and although there is little or no carnitine in plant foods, the human body can produce adequate carnitine from other amino acids, lysine and methionine. Studying mice, scientists found that carnitine was metabolized by intestinal bacteria, producing trimethylamine-N-oxide (TMAO), a substance previously shown in mice to   promote  atherosclerotic plaque development.15 

They then sought to confirm these findings with human subjects Analyzing the blood levels of carnitine and TMAO in humans, they found that the combination of high carnitine and high TMAO was associated with increased likelihood of cardiovascular disease or cardiovascular events (heart attack and stroke). When they gave humans carnitine supplements, interestingly, they found that omnivores produced far more TMAO in response to carnitine than vegans and vegetarians. In addition, the species of gut bacteria in omnivores were different from those in vegetarians and vegans. These results suggest that regularly eating carnitine-containing foods promotes the growth of gut bacteria that can metabolize carnitine into a heart disease-promoting substance.16-18

Further research has found that higher circulating TMAO levels are predictive of a higher mortality risk in patients with diabetes or coronary artery disease, and a greater amount of atherosclerosis.19-21

A similar process occurs with choline; like carnitine, it is metabolized by gut bacteria into TMAO.15,22  Eggs are especially high in choline, and high choline or egg intake has been linked to cardiovascular disease (particularly in people with diabetes),23-26 prostate cancer, and colon cancer.27-30 

Our overall dietary pattern determines the bacteria that live in our gastrointestinal tract, and this research indicates that eating red meat regularly promotes the growth of bacteria that produce harmful substances.

The research also indicates that those who regularly consume a healthful diet of whole plant foods have a healthier microbiome, and are therefore less susceptible to the disease-promoting effects of occasional high-carnitine or high-choline meals. Future studies will continue to uncover more of these intriguing links between diet, gut bacteria, and health.

 
References
  1. Sinha R, Cross AJ, Graubard BI, et al: Meat intake and mortality: a prospective study of over half a million people. Arch Intern Med 2009;169:562-571.
  2. Bernstein AM, Sun Q, Hu FB, et al: Major dietary protein sources and risk of coronary heart disease in women. Circulation 2010;122:876-883.
  3. Pan A, Sun Q, Bernstein AM, et al: Red Meat Consumption and Mortality: Results From 2 Prospective Cohort Studies. Arch Intern Med 2012.
  4. Ascherio A, Willett WC, Rimm EB, et al: Dietary iron intake and risk of coronary disease among men. Circulation 1994;89:969-974.
  5. Larsson SC, Virtamo J, Wolk A: Red meat consumption and risk of stroke in Swedish men. Am J Clin Nutr 2011.
  6. Song M, Fung TT, Hu FB, et al: Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality. JAMA Intern Med 2016.
  7. Tholstrup T, Hjerpsted J, Raff M: Palm olein increases plasma cholesterol moderately compared with olive oil in healthy individuals. Am J Clin Nutr 2011;94:1426-1432.
  8. de Oliveira Otto MC, Alonso A, Lee DH, et al: Dietary intakes of zinc and heme iron from red meat, but not from other sources, are associated with greater risk of metabolic syndrome and cardiovascular disease. J Nutr 2012;142:526-533.
  9. Ahluwalia N, Genoux A, Ferrieres J, et al: Iron status is associated with carotid atherosclerotic plaques in middle-aged adults. J Nutr 2010;140:812-816.
  10. Brewer GJ: Iron and copper toxicity in diseases of aging, particularly atherosclerosis and Alzheimer's disease. Exp Biol Med 2007;232:323-335.
  11. Scharlau D, Borowicki A, Habermann N, et al: Mechanisms of primary cancer prevention by butyrate and other products formed during gut flora-mediated fermentation of dietary fibre. Mutat Res 2009;682:39-53.
  12. Sonnenburg ED, Sonnenburg JL: Starving our microbial self: the deleterious consequences of a diet deficient in microbiota-accessible carbohydrates. Cell Metab 2014;20:779-786.
  13. Neish AS: Microbes in gastrointestinal health and disease. Gastroenterology 2009;136:65-80.
  14. Backhed F: Host responses to the human microbiome. Nutr Rev 2012;70 Suppl 1:S14-17.
  15. Wang Z, Klipfell E, Bennett BJ, et al: Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease. Nature 2011;472:57-63.
  16. Woolston C: Red meat + wrong bacteria = bad news for hearts. 2013. Nature. http://www.nature.com/news/red-meat-wrong-bacteria-bad-news-for-hearts-1.12746. Accessed April 12, 2013.
  17. Koeth RA, Wang Z, Levison BS, et al: Intestinal microbiota metabolism of l-carnitine, a nutrient in red meat, promotes atherosclerosis. Nat Med 2013.
  18. Tang WH, Hazen SL: Microbiome, trimethylamine N-oxide, and cardiometabolic disease. Transl Res 2017;179:108-115.
  19. Tang WH, Wang Z, Li XS, et al: Increased Trimethylamine N-Oxide Portends High Mortality Risk Independent of Glycemic Control in Patients with Type 2 Diabetes Mellitus. Clin Chem 2017;63:297-306.
  20. Senthong V, Wang Z, Li XS, et al: Intestinal Microbiota-Generated Metabolite Trimethylamine-N-Oxide and 5-Year Mortality Risk in Stable Coronary Artery Disease: The Contributory Role of Intestinal Microbiota in a COURAGE-Like Patient Cohort. J Am Heart Assoc 2016;5.
  21. Senthong V, Li XS, Hudec T, et al: Plasma Trimethylamine N-Oxide, a Gut Microbe-Generated Phosphatidylcholine Metabolite, Is Associated With Atherosclerotic Burden. J Am Coll Cardiol 2016;67:2620-2628.
  22. Tang WH, Wang Z, Levison BS, et al: Intestinal microbial metabolism of phosphatidylcholine and cardiovascular risk. N Engl J Med 2013;368:1575-1584.
  23. Djousse L, Gaziano JM: Egg consumption in relation to cardiovascular disease and mortality: the Physicians' Health Study. Am J Clin Nutr 2008;87:964-969.
  24. Qureshi AI, Suri FK, Ahmed S, et al: Regular egg consumption does not increase the risk of stroke and cardiovascular diseases. Med Sci Monit 2007;13:CR1-8.
  25. Hu FB, Stampfer MJ, Rimm EB, et al: A prospective study of egg consumption and risk of cardiovascular disease in men and women. JAMA 1999;281:1387-1394.
  26. Spence JD, Jenkins DJ, Davignon J: Egg yolk consumption and carotid plaque. Atherosclerosis 2012;224:469-473.
  27. Snowdon DA, Phillips RL, Choi W: Diet, obesity, and risk of fatal prostate cancer. Am J Epidemiol 1984;120:244-250.
  28. Richman EL, Kenfield SA, Stampfer MJ, et al: Egg, red meat, and poultry intake and risk of lethal prostate cancer in the prostate-specific antigen-era: incidence and survival. Cancer Prev Res (Phila) 2011;4:2110-2121.
  29. Richman EL, Kenfield SA, Stampfer MJ, et al: Choline intake and risk of lethal prostate cancer: incidence and survival. Am J Clin Nutr 2012;96:855-863.
  30. Tse G, Eslick GD: Egg consumption and risk of GI neoplasms: dose-response meta-analysis and systematic review. Eur J Nutr 2014.
GO-reversing-type-2-diabetes  GO-diabetes  GO-type1-diabetes  GO-reverse-diabetes-for-good  GO-the-simple-way-to-lower-blood-sugar  GO-type-2-diabetes  GO-treatment-of-type-2-diabetes  GO-type-1-diabetes