Eat Plant Protein to Live Longer

April 13, 2021 by Joel Fuhrman, MD

Scientific research continues to show consuming red and processed meats or a high-animal protein diet has a profound damaging effects on overall health and longevity. It is vitally important that meat in our diet should be replaced (or at least greatly limited) in favor of foods that are proven to offer protection against cancer – such as green vegetables, berries, beans, nuts and seeds. This should not be seen as controversial and is supported by an overwhelming amount of data. 

Long-term studies

Large, long-term studies investigating intakes of animal and plant protein with regard to mortality have consistently concluded that more plant protein and less animal protein is linked to a longer life.1-4 Studies consistently link greater red meat consumption to a greater risk of premature death.5-7 Here’s an example:

Related: How Plant Protein Wins Over Animal Protein

A 2016 study published in JAMA Internal Medicine investigated the relationship between animal vs. plant protein sources and mortality risk from almost 30 years of follow-up from the Nurses’ Health Study and Health Professionals Follow-up Study. Together, these two studies included over 170,000 participants.

Interesting findings came out of one particular question the researchers asked:

What would happen if the participants replaced some of their animal protein with plant protein?

They analyzed the data to estimate how participants’ risk of death would change from all causes over the follow-up period if some of the animal protein sources (equivalent to 3 percent of total daily calories) were replaced with plant protein sources:

  • Replace processed red meat: 34 percent decrease in risk
  • Replace unprocessed red meat: 12 percent decrease in risk
  • Replace poultry: 6 percent decrease in risk
  • Replace fish: 6 percent decrease in risk
  • Replace eggs: 19 percent decrease in risk
  • Replace dairy: 8 percent decrease in risk3

Related: The Protein Problem: How the source affects cardiovascular risk

Related: Are Eggs Healthy? Learn The Truth

Higher intake of plant protein sources are associated with better health: for example, seeds and nuts reduce the risk of cardiovascular disease and are linked to longevity, and micronutrient and fiber-rich beans are linked to improved blood pressure, LDL cholesterol, body weight, insulin sensitivity and enhanced lifespan.4, 8-13

Related: Your gut microbiome influences immune function (and beans keep it healthy)

Related: Nuts and Seeds Help Keep Disease Away

Prospective cohort studies are observational and cannot prove causality, but these studies are crucial to our understanding of health and longevity, because heart disease and cancer – our two biggest killers – develop over the course of multiple decades, not just a few months. Studies that follow tens of thousands of people for 10 or 20 years or more, and evaluate hard endpoints (death, heart attack, stroke, cancer, etc.) provide valuable insights into the habits that may promote or prevent these diseases. The significance of findings from observational studies is supported by laboratory studies showing there are plausible mechanisms for the association – good reasons why it’s not just a random correlation, but likely a causal relationship.

Many meat-centered diet proponents dismiss these important studies out of hand, ignoring the careful collection of data and complex mathematical analysis by skilled epidemiologists that controls for potential confounding factors and detects potentially significant associations. 

The correlations between animal protein intake and all-cause mortality in long-term prospective studies are consistent with other observational studies on specific diseases, and are backed up by laboratory studies that have uncovered the plausible cellular and molecular mechanisms behind the correlations:

  • High animal protein intake excessively elevates insulin-like growth factor 1 (IGF-1), which promotes cancer development.14-18 
  • Research on nutrient-sensing pathways that respond to protein intake suggests reducing essential amino acid intake (i.e. reducing animal protein) promotes longevity.19 (Note that the elderly require more protein than younger adults.20, 21)
  • The pro-inflammatory effects of dietary saturated animal fats.22-25
  • The pro-oxidant and pro-inflammatory properties of excess heme iron.26, 27
  • Cooking-produced carcinogens in meats, such as heterocyclic amines and polycyclic aromatic hydrocarbons.28-31
  • Genotoxic N-nitroso compounds produced from processed meats.30-33
  • Detrimental effects of carnitine and choline on the gut microbiome that promote inflammation.34-37

Related: Optimal IGF-1 Levels for Longevity

Related: Animal products, the microbiome, and heart disease

Short-term studies

Although eating a keto or carnivores’ diet can lower blood sugar and promote weight loss in the short term, the long-term effects of a diet so high in animal products (according to the preponderance of evidence) is damaging over the long term. That is why I reiterated that it is important to see the long-term studies with hard endpoints. Looking at short-term weight loss studies will lead you on a path to damage your potential for optimal longevity.

Related: Why a Nutritarian Diet is Superior to the Ketogenic Diet in the Fight Against Cancer

Although the disease-promoting effects take many years to build up, several short-term studies point to the beginnings of the damage of a high-animal product diet:

  • Measured after a single meal, butter impaired vascular function compared to nuts and other predominantly unsaturated plant fats.38
  • A study comparing Atkins, South Beach, and Ornish weight maintenance diets (all with the same calorie counts) assigned participants to each diet for four weeks each. At the end of the Atkins diet phase, LDL cholesterol was higher and vascular function lower compared to the other diets.39 
  • Participants (who lived at the study site during the study) were fed 420 g red meat or a vegetarian meal daily for 15 days, with the rest of their diets kept exactly the same. Stool samples and colon cells collected after 10 days on each diet showed an increase in production of carcinogenic N-nitroso compounds during the red meat diet compared to the vegetarian diet, and an increase in N-nitroso compounds binding to DNA in colon cells (which leads to DNA damage and colon cancer).40
  • A study comparing about two servings daily of fiber-rich whole grains to red meat for three weeks each suggested the whole grain diet improved gut microbiome diversity compared to the red meat diet. Body fat mass was also lower after the whole grain intervention.41
  • After four weeks, a diet containing red meat increased production of the pro-inflammatory compound TMAO, compared to white meat and vegetarian diets.36

Meat-heavy diets get one important thing right: They cut out weight gain-promoting, disease-promoting high-glycemic refined carbohydrates. But large amounts of animal products are unquestionably disease-promoting, too.  The Nutritarian diet does more than just restrict one type of harmful food. It limits or completely avoids all other disease-promoting foods and focuses heavily on foods that are richest in protective nutrients and are linked in scientific studies most consistently to a lower risk of cardiovascular disease, cancer, and other chronic diseases.

  1. Budhathoki S, Sawada N, Iwasaki M, et al. Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality. JAMA Intern Med 2019. doi: 10.1001/jamainternmed.2019.2806

  2. Huang J, Liao LM, Weinstein SJ, et al. Association Between Plant and Animal Protein Intake and Overall and Cause-Specific Mortality. JAMA Intern Med 2020. doi: 10.1001/jamainternmed.2020.2790

  3. 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, 176:1453-1463. doi: 10.1001/jamainternmed.2016.4182

  4. Tharrey M, Mariotti F, Mashchak A, et al. Patterns of plant and animal protein intake are strongly associated with cardiovascular mortality: the Adventist Health Study-2 cohort. Int J Epidemiol 2018. doi: 10.1093/ije/dyy030

  5. Wang X, Lin X, Ouyang YY, et al. Red and processed meat consumption and mortality: dose-response meta-analysis of prospective cohort studies. Public Health Nutr 2016, 19:893-905. doi: 10.1017/S1368980015002062

  6. Pan A, Sun Q, Bernstein AM, et al. Red Meat Consumption and Mortality: Results From 2 Prospective Cohort Studies. Arch Intern Med 2012. doi: 10.1001/archinternmed.2011.2287Sinha 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. doi: 169/6/562 [pii] 10.1001/archinternmed.2009.6

  7. Grosso G, Yang J, Marventano S, et al. Nut consumption on all-cause, cardiovascular, and cancer mortality risk: a systematic review and meta-analysis of epidemiologic studies. Am J Clin Nutr 2015, 101:783-793. doi: 10.3945/ajcn.114.099515

  8. Jenkins DJ, Kendall CW, Augustin LS, et al. Effect of legumes as part of a low glycemic index diet on glycemic control and cardiovascular risk factors in type 2 diabetes mellitus: a randomized controlled trial. Arch Intern Med 2012, 172:1653-1660. doi: 10.1001/2013.jamainternmed.70

  9. Bazzano LA, Thompson AM, Tees MT, et al. Non-soy legume consumption lowers cholesterol levels: a meta-analysis of randomized controlled trials. Nutrition, metabolism, and cardiovascular diseases : NMCD 2011, 21:94-103. doi: 10.1016/j.numecd.2009.08.012

  10. Papanikolaou Y, Fulgoni VL, 3rd. Bean consumption is associated with greater nutrient intake, reduced systolic blood pressure, lower body weight, and a smaller waist circumference in adults: results from the National Health and Nutrition Examination Survey 1999-2002. J Am Coll Nutr 2008, 27:569-576. doi:

  11. Darmadi-Blackberry I, Wahlqvist ML, Kouris-Blazos A, et al. Legumes: the most important dietary predictor of survival in older people of different ethnicities. Asia Pac J Clin Nutr 2004, 13:217-220. doi:

  12. Li SS, Blanco Mejia S, Lytvyn L, et al. Effect of Plant Protein on Blood Lipids: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Am Heart Assoc 2017, 6. doi: 10.1161/JAHA.117.006659

  13. Travis RC, Appleby PN, Martin RM, et al. A Meta-analysis of Individual Participant Data Reveals an Association between Circulating Levels of IGF-I and Prostate Cancer Risk. Cancer Res 2016, 76:2288-2300. doi: 10.1158/0008-5472.CAN-15-1551

  14. Vigneri PG, Tirro E, Pennisi MS, et al. The Insulin/IGF System in Colorectal Cancer Development and Resistance to Therapy. Front Oncol 2015, 5:230. doi: 10.3389/fonc.2015.00230

  15. Anisimov VN, Bartke A. The key role of growth hormone-insulin-IGF-1 signaling in aging and cancer. Crit Rev Oncol Hematol 2013, 87:201-223. doi: 10.1016/j.critrevonc.2013.01.005

  16. Key TJ, Appleby PN, Reeves GK, Roddam AW. Insulin-like growth factor 1 (IGF1), IGF binding protein 3 (IGFBP3), and breast cancer risk: pooled individual data analysis of 17 prospective studies. Lancet Oncol 2010, 11:530-542. doi: 10.1016/S1470-2045(10)70095-4

  17. Kaaks R. Nutrition, insulin, IGF-1 metabolism and cancer risk: a summary of epidemiological evidence. Novartis Found Symp 2004, 262:247-260; discussion 260-268. doi:

  18. Mirzaei H, Raynes R, Longo VD. The conserved role of protein restriction in aging and disease. Curr Opin Clin Nutr Metab Care 2016, 19:74-79. doi: 10.1097/MCO.0000000000000239

  19. Bauer J, Biolo G, Cederholm T, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc 2013, 14:542-559. doi: 10.1016/j.jamda.2013.05.021

  20. Volpi E, Campbell WW, Dwyer JT, et al. Is the optimal level of protein intake for older adults greater than the recommended dietary allowance? J Gerontol A Biol Sci Med Sci 2013, 68:677-681. doi: 10.1093/gerona/gls229

  21. Erridge C. The capacity of foodstuffs to induce innate immune activation of human monocytes in vitro is dependent on food content of stimulants of Toll-like receptors 2 and 4. Br J Nutr 2011, 105:15-23. doi: 10.1017/S0007114510003004

  22. Erridge C, Attina T, Spickett CM, Webb DJ. A high-fat meal induces low-grade endotoxemia: evidence of a novel mechanism of postprandial inflammation. Am J Clin Nutr 2007, 86:1286-1292. doi: 10.1093/ajcn/86.5.1286

  23. Masson CJ, Mensink RP. Exchanging saturated fatty acids for (n-6) polyunsaturated fatty acids in a mixed meal may decrease postprandial lipemia and markers of inflammation and endothelial activity in overweight men. J Nutr 2011, 141:816-821. doi: 10.3945/jn.110.136432

  24. Fritsche KL. The science of fatty acids and inflammation. Adv Nutr 2015, 6:293S-301S. doi: 10.3945/an.114.006940

  25. Cornelissen A, Guo L, Sakamoto A, et al. New insights into the role of iron in inflammation and atherosclerosis. EBioMedicine 2019, 47:598-606. doi: 10.1016/j.ebiom.2019.08.014

  26. Brewer GJ. Risks of copper and iron toxicity during aging in humans. Chemical research in toxicology 2010, 23:319-326. doi: 10.1021/tx900338d

  27. Zheng W, Lee S-A. Well-Done Meat Intake, Heterocyclic Amine Exposure, and Cancer Risk. Nutrition and Cancer 2009, 61:437-446. doi: 10.1080/01635580802710741

  28. National Cancer Institute. Chemicals in Meat Cooked at High Temperatures and Cancer Risk. 

  29. International Agency for Research on Cancer, World Health Organization. Press Relsease No. 240. IARC Monographs evaluate consumption of red meat and processed meat. 2015. 

  30. Turesky RJ. Mechanistic Evidence for Red Meat and Processed Meat Intake and Cancer Risk: A Follow-up on the International Agency for Research on Cancer Evaluation of 2015. Chimia (Aarau) 2018, 72:718-724. doi: 10.2533/chimia.2018.718

  31. Lunn JC, Kuhnle G, Mai V, et al. The effect of haem in red and processed meat on the endogenous formation of N-nitroso compounds in the upper gastrointestinal tract. Carcinogenesis 2007, 28:685-690. doi: 10.1093/carcin/bgl192

  32. Herrmann SS, Granby K, Duedahl-Olesen L. Formation and mitigation of N-nitrosamines in nitrite preserved cooked sausages. Food Chem 2015, 174:516-526. doi: 10.1016/j.foodchem.2014.11.101

  33. Koeth RA, Wang Z, Levison BS, et al. Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis. Nat Med 2013, 19:576-585. doi: 10.1038/nm.3145

  34. Tang WH, Wang Z, Levison BS, et al. Intestinal microbial metabolism of phosphatidylcholine and cardiovascular risk. N Engl J Med 2013, 368:1575-1584. doi: 10.1056/NEJMoa1109400

  35. Wang Z, Bergeron N, Levison BS, et al. Impact of chronic dietary red meat, white meat, or non-meat protein on trimethylamine N-oxide metabolism and renal excretion in healthy men and women. Eur Heart J 2019, 40:583-594. doi: 10.1093/eurheartj/ehy799

  36. Wang Z, Klipfell E, Bennett BJ, et al. Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease. Nature 2011, 472:57-63. doi: 10.1038/nature09922

  37. Keogh JB, Grieger JA, Noakes M, Clifton PM. Flow-mediated dilatation is impaired by a high-saturated fat diet but not by a high-carbohydrate diet. Arterioscler Thromb Vasc Biol 2005, 25:1274-1279. doi: 10.1161/01.ATV.0000163185.28245.a1

  38. Miller M, Beach V, Sorkin JD, et al. Comparative effects of three popular diets on lipids, endothelial function, and C-reactive protein during weight maintenance. J Am Diet Assoc 2009, 109:713-717. doi: 10.1016/j.jada.2008.12.023

  39. Lewin MH, Bailey N, Bandaletova T, et al. Red meat enhances the colonic formation of the DNA adduct O6-carboxymethyl guanine: implications for colorectal cancer risk. Cancer Res 2006, 66:1859-1865. doi: 10.1158/0008-5472.CAN-05-2237

  40. Foerster J, Maskarinec G, Reichardt N, 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 2014, 9:e109606. doi: 10.1371/journal.pone.0109606

Joel Fuhrman, M.D. is a board-certified family physician, seven-time New York Times bestselling author and internationally recognized expert on nutrition and natural healing, who specializes in preventing and reversing disease through nutritional methods. Dr. Fuhrman coined the term “Nutritarian” to describe his longevity-promoting, nutrient dense, plant-rich eating style.
For over 30 years, Dr. Fuhrman has shown that it is possible to achieve sustainable weight loss and reverse heart disease, diabetes and many other illnesses using smart nutrition. In his medical practice, and through his books and PBS television specials, he continues to bring this life-saving message to hundreds of thousands of people around the world.


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