What is the optimal diet for athletes? While I don’t believe there is one optimal diet for every person, I do think there are characteristics that all healthy diets share. Namely, they’re ancestral—based on the types of foods that our bodies evolved to thrive on—and they include a mix of nutrient-dense plant and animal foods.
A recent documentary called The Game Changers claims otherwise. The experts and celebrities featured in the film argue that a plant-based, vegan diet is optimal for athletes and that animal foods are harmful for athletic performance and overall health.
There are a lot of myths and misconceptions on this topic, so I wanted to take this opportunity to debunk some of the biggest claims made in The Game Changers. For a full breakdown of what this movie gets wrong, download my Show Notes, and listen to my appearance on The Joe Rogan Experience.
Download Chris’ Show Notes
I’ve conducted extensive research on the real impact of a plant-based diet over an omnivorous, ancestral diet. I’m sharing that research with you now in hopes that it helps clear up some of the misconceptions on vegan diets.
What Is The Game Changers?
The Game Changers is an agenda-driven film, not an objective analysis of an optimal diet for athletes. The purpose of this film is to advocate for a plant-based diet. It hasn’t been peer-reviewed, and it plays very fast and loose with the science. It’s propaganda for veganism, pure and simple.
This is a very slick, well-done film, and it has the potential to mislead a lot of people. But it’s full of misleading statements, half-truths, flat-out falsehoods, flawed logic, and absurdities. I found problems with a number of claims made in the movie, including:
- The gorilla analogy
- The idea that peanut butter has as much protein as beef or eggs
- The gladiator diet
- The impact of protein on strength and health
- Where B12 comes from
These are examples of some very misleading and disingenuous uses of science. For instance, you would have to eat almost one-third of a cup of peanut butter to equal the protein in 3 oz of beef or three eggs; stories about gladiators’ diets ignore important details like the fact that they were being fed the cheapest possible slave diet and had a life expectancy of about two years; and it isn’t easy to consume the amount of amino acids you need for strength and muscle mass when you’re eating only plants—unless you include ultra-processed protein powders in your diet.
Post-debate critiques:
- “Did James Wilks Get Anything Right Against Chris Kresser? Joe Rogan Debate Breakdown,” Food Lies, YouTube
- @ChrisMasterjohn Twitter Thread, Chris Masterjohn
For more:
- “What Is an Ancestral Diet and How Does It Help You?” Chris Kresser
- “RHR: Why the Optimal Human Diet Includes Animal Protein,” Chris Kresser
- “What Is the Optimal Human Diet?” Chris Kresser
- “Why You Should Think Twice About Vegetarian and Vegan Diets,” Chris Kresser
- “B12 Deficiency: What Everyone (Especially Vegetarians) Should Know,” Chris Kresser
References and resources:
- The Game Changers film, GameChangersMovie.com
- “Ingredion invests $140 million for plant-based proteins,” MarketWatch
- MUSE Kitchen, MUSE School
- Propaganda definition, Lexico
- “Meat and Nicotinamide: A Causal Role in Human Evolution, History, and Demographics,” International Journal of Tryptophan Research
- “The Critical Role Played by Animal Source Foods in Human (Homo) Evolution,” The Journal of Nutrition
- “Impact of meat and Lower Palaeolithic food processing techniques on chewing in humans,” Nature
- “Origins of the Human Predatory Pattern: The Transition to Large-Animal Exploitation by Early Hominins,” Current Anthropology
- “Did Cooked Tubers Spur the Evolution of Big Brains?” Science
- Gorilla, San Diego Zoo
- “Potential impact of the digestible indispensable amino acid score as a measure of protein quality on dietary regulations and health,” Nutrition Reviews
- “PSIII-21 Processing of food proteins of animal origin sometimes, but not always, increases values for Digestible Indispensable Amino Acid Scores,” Journal of Animal Science
- “Digestible indispensable amino acid scores of nine cooked cereal grains,” The British Journal of Nutrition
- SELF Nutrition Data, Nutritiondata.self.com
- FoodData Central: Fish, salmon, coho, wild, cooked, moist heat, USDA
- FoodData Central: Lettuce, iceberg (includes crisphead types), raw, USDA
- “The Impact of Egg Nutrient Composition and Its Consumption on Cholesterol Homeostasis,” Cholesterol
- FoodData Central: Lettuce, iceberg (includes crisphead types), raw, USDA
- “Meeting the Vitamin A Requirement: The Efficacy and Importance of β-Carotene in Animal Species,” The Scientific World Journal
- FoodData Central: Oysters, raw, USDA
- “The Gladiator Diet,” Archaeology
- “Phelps’ Pig Secret: He’s Boy Gorge,” New York Post
- “Usain Bolt Ate 100 Chicken McNuggets a Day in Beijing and Somehow Won Three Gold Medals,” Time
- “Bolt Is World’s Fastest—By a Mile,” The New York Times
- “Nutritional considerations for vegetarian athletes,” Nutrition
- “Red meat consumption and mortality: results from 2 prospective cohort studies,” Archives of Internal Medicine
- “Systematic review and meta-analysis of dietary carbohydrate restriction in patients with type 2 diabetes,” BMJ Open Diabetes Research & Care
- Coprophagy, ScienceDirect
- “B12 in Plant Foods,” Vegan Health
- “Vitamin B-12 status, particularly holotranscobalamin II and methylmalonic acid concentrations, and hyperhomocysteinemia in vegetarians,” The American Journal of Clinical Nutrition
- “Serum concentrations of vitamin B12 and folate in British male omnivores, vegetarians, and vegans: results from a cross-sectional analysis of the EPIC-Oxford cohort study,” The European Journal of Clinical Nutrition
- “Homocysteine and vitamins in cardiovascular disease,” Clinical Chemistry
- “Vitamin B-12 and homocysteine status among vegetarians: a global perspective,” The American Journal of Clinical Nutrition
- “Plasma total homocysteine status of vegetarians compared with omnivores: a systematic review and meta-analysis,” The British Journal of Nutrition
- “Vitamin B-12 and homocysteine status among vegetarians: a global perspective,” The American Journal of Clinical Nutrition
- “The usefulness of holotranscobalamin in predicting vitamin B12 status in different clinical settings,” Current Drug Metabolism
- “How prevalent is vitamin B(12) deficiency among vegetarians?” Nutrition Reviews
Is a Vegan Diet Optimal for Athletic Performance?
One of the primary arguments made in The Game Changers is that a vegan diet is optimal for athletic performance. Experts in the film make a number of dubious claims in this area, including:
- Sacrificing carbohydrate calories for protein calories will lead to chronic fatigue and loss of stamina
- Vegetarian athletes get enough protein in their diets
- Eating too much protein is dangerous for your health
- Athletes can get enough essential amino acids solely from plant foods
- And many, many more
I encourage you to download my Show Notes for a full breakdown of each of these claims, but overall, it’s hard to imagine how athletes can get enough protein on a plant-based diet. Athletes in general need more protein than the recommended dietary allowance (RDA), and the amount they need will depend on the type of sport they’re involved in, as well as their health status, age, sex, and more. While carbs are a great source of energy for explosive, glycolytic activities, in endurance sports, fat can be burned as the primary fuel source.
Protein quality matters just as much as quantity. Protein quality is a function of amino acid profile and bioavailability, and plant proteins are inferior to animal proteins on both counts. Animal proteins concentrate essential amino acids, so you get a lot more of them in a smaller amount of food (without having to rely on ultra-processed protein powders). Animal proteins have better bioavailability than plant proteins, meaning your body is better able to digest and absorb them. What’s more, plant proteins are missing a number of important nutrients athletes need, like vitamin B12, iron, creatine, calcium, and many, many more.
For more:
- “What Is an Ancestral Diet and How Does It Help You?” Chris Kresser
- Chart: Amino Acid Profile for Beef vs. Plant Proteins, Chris Kresser
- “B12 Deficiency: What Everyone (Especially Vegetarians) Should Know,” Chris Kresser
- “Why You Should Think Twice about Taking Calcium Supplements” Chris Kresser
References and resources:
- “Keto-Adaptation and Endurance Exercise Capacity, Fatigue Recovery, and Exercise-Induced Muscle and Organ Damage Prevention: A Narrative Review,” Sports
- “American Zach Bitter Crushes 100-Mile World Record With 6:48-Mile Pace,” Runner’s World
- “Bioconversion of dietary provitamin A carotenoids to vitamin A in humans,” The American Journal of Clinical Nutrition
- “Mammalian carotenoid absorption and metabolism,” Pure and Applied Chemistry
- “Vitamin A intake and hip fractures among postmenopausal women,” JAMA
- “Nutrient profiles of vegetarian and nonvegetarian dietary patterns,” Journal of the Academy of Nutrition and Dietetics
- “Evidence that protein requirements have been significantly underestimated,” Current Opinion in Clinical Nutrition & Metabolic Care
- “Reevaluation of the protein requirement in young men with the indicator amino acid oxidation technique,” The American Journal of Clinical Nutrition
- “Dietary Protein Requirement of Men >65 Years Old Determined by the Indicator Amino Acid Oxidation Technique Is Higher than the Current Estimated Average Requirement,” The Journal of Nutrition
- “Dietary protein requirement of female adults >65 years determined by the indicator amino acid oxidation technique is higher than current recommendations,” The Journal of Nutrition
- “How much protein do you need per day?,” Examine.com
- FastStats: Overweight Prevalence, CDC
- “Homeostatic regulation of protein intake: in search of a mechanism,” The American Journal of Physiology-Regulatory, Integrative and Comparative Physiology
- “Dietary protein intake and renal function,” Nutrition & Metabolism
- “Do regular high protein diets have potential health risks on kidney function in athletes?,” International Journal of Sport Nutrition and Exercise Metabolism
- “The acid-base hypothesis: diet and bone in the Framingham Osteoporosis Study,” European Journal of Nutrition
- “Prospective study of dietary protein intake and risk of hip fracture in postmenopausal women,” The American Journal of Clinical Nutrition
- “Protein consumption and bone mineral density in the elderly: the Rancho Bernardo Study,” American Journal of Epidemiology
- “Branched-chain amino acids and muscle protein synthesis in humans: myth or reality?” Journal of the International Society of Sports Nutrition
- FoodData Central: Beef, top sirloin, steak, separable lean only, trimmed to 1/8″ fat, choice, raw, USDA
- FoodData Central: Lentils, mature seeds, cooked, boiled, without salt, USDA
- FoodData Central: Chickpeas, dry, cooked, fat not added in cooking, USDA
- “In Search For The Highest Quality Protein (And The Issues It Causes For Diet Guidelines),” Alex Fergus
- “Effect of creatine and weight training on muscle creatine and performance in vegetarians,” Medicine & Science in Sports & Exercise
- “Normal reference values for creatine, creatinine, and carnitine are lower in vegetarians,” Clinical Chemistry
- “Effect of creatine supplementation and a lacto-ovo-vegetarian diet on muscle creatine concentration,” International Journal of Sport Nutrition and Exercise Metabolism
- “Vegan diets: practical advice for athletes and exercisers,” Journal of the International Society of Sports Nutrition
- “Taurine concentrations in the diet, plasma, urine and breast milk of vegans compared with omnivores,” British Journal of Nutrition
- “Taurine: a conditionally essential amino acid in humans? An overview in health and disease,” Nutrición Hospitalaria
- “Plasma concentrations and intakes of amino acids in male meat-eaters, fish-eaters, vegetarians and vegans: a cross-sectional analysis in the EPIC-Oxford cohort,” European Journal of Clinical Nutrition
- “Vitamin B1, B2 and B6 status of vegetarians,” Journal of the Medical Association of Thailand
- “Effect of vegetarian diets on bone mineral density: a Bayesian meta-analysis,” The American Journal of Clinical Nutrition
- “EPIC-Oxford: lifestyle characteristics and nutrient intakes in a cohort of 33 883 meat-eaters and 31 546 non meat-eaters in the UK,” Public Health Nutrition
- “Nutrient intakes and eating behavior scores of vegetarian and nonvegetarian women,” Journal of the American Dietetic Association
- Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc, Institute of Medicine (US) Panel on Micronutrients
- “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
- “Is iron and zinc nutrition a concern for vegetarian infants and young children in industrialized countries?” The American Journal of Clinical Nutrition
- “Dietary iron intake and iron status of German female vegans: results of the German vegan study,” Annals of Nutrition and Metabolism
- “Iron-deficiency anemia,” The New England Journal of Medicine
- “Nutrient intake and iron status of Australian male vegetarians,” The European Journal of Clinical Nutrition
- “Bioavailability of iron, zinc, and other trace minerals from vegetarian diets,” The American Journal of Clinical Nutrition
- “Nutrient intake and haematological status of vegetarians and age-sex matched omnivores,” The European Journal of Clinical Nutrition
- “Growth, development, and physical fitness of Flemish vegetarian children, adolescents, and young adults,” The American Journal of Clinical Nutrition
- “Effects of an omnivorous diet compared with a lactoovovegetarian diet on resistance-training-induced changes in body composition and skeletal muscle in older men,” The American Journal of Clinical Nutrition
- “Meat supplementation improves growth, cognitive, and behavioral outcomes in Kenyan children,” The Journal of Nutrition
- “Physical fitness, anthropometric and metabolic parameters in vegetarian athletes,” The Journal of Sports Medicine and Physical Fitness
- “A Comparison of a Vegetarian and Non-Vegetarian Diet in Indian Female Athletes in Relation to Exercise Performance,” Journal of Exercise Science and Physiotherapy
- Robert Oberst VS. Patrik Baboumian – What I eat in a Day, YouTube
- “Veganism, vegetarianism, bone mineral density, and fracture risk: a systematic review and meta-analysis,” Nutrition Reviews
What Are the Effects of a Vegan Diet on Athletic Performance?
The key question is not whether it’s possible for athletes to thrive on a vegan diet, but whether it’s likely. There are always outliers, but the exceptions don’t make the rule. Just because some of the athletes in The Game Changers excel on a vegan diet, that doesn’t mean that everyone will.
There are many non-dietary factors influence athletic performance, including genetics, epigenetics, stress, sleep, work ethic, talent, coaching, etc. These are significant. What’s more, many of the athletes featured didn’t start out on a vegan diet. They switched from a standard American diet to a whole-foods, non-processed vegan diet. But what might have happened if they switched to a “nutrivore” diet with plenty of nutrient-dense animal and plant foods? Would they have done better than they did on a vegan diet? Yes, this is plausible.
In fact, the common trajectory for vegan athletes involves a “honeymoon” period. Initially, their performance stays the same or may even improve for a short time. But after a while, you see a significant decline in performance and well-being. I’ve also seen this to be true with many of my patients at the California Center for Functional Medicine, some of whom are high-level athletes, and others who aren’t. I don’t think the athletes featured in The Game Changers are examples of the core argument of the movie, which is that a vegan/plant-based diet improves athletic performance (and animal protein harms it).
For more:
- “What Is Nutrient Density and Why Is It Important?” Chris Kresser
References and resources:
- “Achieving optimal essential fatty acid status in vegetarians: current knowledge and practical implications,” The American Journal of Clinical Nutrition
- “Long-chain conversion of [13C]linoleic acid and alpha-linolenic acid in response to marked changes in their dietary intake in men,” Journal of Lipid Research
- “DHA status of vegetarians,” Prostaglandins, Leukotrienes & Essential Fatty Acids
- “Beta-carotene conversion to vitamin A decreases as the dietary dose increases in humans,” The Journal of Nutrition
- “The challenge to reach nutritional adequacy for vitamin A: β-carotene bioavailability and conversion–evidence in humans,” The American Journal of Clinical Nutrition
- “Effects of beetroot juice supplementation on intermittent high-intensity exercise efforts,” Journal of the International Society of Sports Nutrition
- Patrik Baboumian, Wikipedia
- Morgan Mitchell Profile, World Athletics
- United States – Women’s 400 Meters Rankings, Athletic.net
- “Cam Newton has likely played his last game for Panthers,” ESPN
- “How Cam Newton’s vegan diet may be hurting Panthers QB’s play and injury recovery,” The Charlotte Observer
- “Orlando Pride’s Alex Morgan Out for Remainder of NWSL Season With Knee Injury,” Sports Illustrated
- “Damian Lillard ends strict vegan diet,” The Undefeated
- “Texans’ Foster not afraid to cheat on vegan diet,” The Houston Chronicle
- “Hey, Arian Foster—Where’s the Beef? Going Vegan in the NFL,” Sports Illustrated
- “Why RB David Johnson Lost a Scary Amount of Weight After Going Vegan,” STACK
- “These 19 elite athletes are vegan — here’s what made them switch their diet,” Business Insider
- “Nutritional Support for Exercise-Induced Injuries,” Sports Medicine
- “International Society of Sports Nutrition Position Stand: protein and exercise,” Journal of the International Society of Sports Nutrition
- “Anti-Inflammatory Effects and Joint Protection in Collagen-Induced Arthritis after Treatment with IQ-1S, a Selective c-Jun N-Terminal Kinase Inhibitor,” Journal of Pharmacology and Experimental Therapeutics
- “24-Week study on the use of collagen hydrolysate as a dietary supplement in athletes with activity-related joint pain,” Current Medical Research and Opinion
- “Effects of whey and fortified collagen hydrolysate protein supplements on nitrogen balance and body composition in older women,” Journal of the American Dietetic Association
- “Localization of type I and III collagen and fibronectin production in injured gastrocnemius muscle,” Laboratory Investigation
- “How nutrition and exercise maintain the human musculoskeletal mass,” Journal of Anatomy
- “Acute energy deprivation affects skeletal muscle protein synthesis and associated intracellular signaling proteins in physically active adults,” The Journal of Nutrition
- “Reduced resting skeletal muscle protein synthesis is rescued by resistance exercise and protein ingestion following short-term energy deficit,” American Journal of Physiology-Endocrinology and Metabolism
Are Animal Proteins and Foods Harmful?
One of the key claims in the film is that animal products increase the risk of disease and shortened lifespan. But The Game Changers makes the same mistake that other films and even scientific studies that advocate plant-based studies make: ignoring the importance of food quality.
Eating a nutrient-dense, ancestral diet based on whole foods is not the same as eating an ultra-processed standard American diet. If an athlete was subsisting on a junk food diet of Popeyes and KFC, it makes sense that they may feel better on a higher quality diet that includes fresh fruits and vegetables in place of fried, processed, and refined foods.
Observational studies on the effects of animal protein suffer from a similar problem, which is known as the “healthy-user bias.” People who engage in a behavior that is seen as “healthy” are more likely to engage in other behaviors that are also perceived as healthy, and vice versa. Red meat, for example, has been perceived as unhealthy for so long that people who eat more of it are also more likely to engage in unhealthy habits, like smoking, being physically inactive, and eating fewer fruits and vegetables. Confounding factors like the healthy-user bias influence research and are difficult to control.
Many observational studies look at diets completely out of context—focusing solely on nutrients, isolated food components, or biomarkers, without considering the overall quality of the diet. One of the inevitable results of doing this is that many observational studies end up comparing two groups of people that are not at all similar, and this casts doubt on the findings. This is how we get misleading claims that vegetarians and vegans live longer than omnivores, or red meat causes serious health conditions like cancer or cardiovascular disease, or that eating meat disrupts your gut microbiome.
For more:
- Why Eating Meat Is Good for You, Chris Kresser
- The Truth about Red Meat eBook, Chris Kresser
- “Why You Should Be Skeptical of the Latest Nutrition Headlines” Part 1 and Part 2, Chris Kresser
- “Do Vegetarians and Vegans Live Longer Than Meat Eaters?” Chris Kresser
- “Do Your Kids Need to Eat Meat to Thrive?” Chris Kresser
References and resources:
- “Health risk factors associated with meat, fruit and vegetable consumption in cohort studies: A comprehensive meta-analysis,” PLOS ONE
- “On the Ideology of Nutritionism,” Gastronomica: The Journal of Critical Food Studies
- “Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion,” JAMA
- Healthy Food Choices – Canada’s Food Guide, Government of Canada
- “Vegetarian diet and all-cause mortality: Evidence from a large population-based Australian cohort – the 45 and Up Study,” Preventative Medicine
- 2015-2020 Dietary Guidelines: Answers to Your Questions, ChooseMyPlate
- “Evidence from prospective cohort studies does not support current dietary fat guidelines: a systematic review and meta-analysis,” British Journal of Sports Medicine
- “Evidence from randomised controlled trials does not support current dietary fat guidelines: a systematic review and meta-analysis,” Open Heart
- “Fat or fiction: the diet-heart hypothesis,” BMJ Evidence-Based Medicine
- “Unprocessed Red Meat and Processed Meat Consumption: Dietary Guideline Recommendations From the Nutritional Recommendations (NutriRECS) Consortium,” Annals of Internal Medicine
- Redesigning the Process for Establishing the Dietary Guidelines for Americans, National Academies Press
- “Opinion: The latest flip-flop on red meat uses best science in place of best guesses,” Los Angeles Times
- “Hass Avocado Modulates Postprandial Vascular Reactivity and Postprandial Inflammatory Responses To a Hamburger Meal In Healthy Volunteers,” Food & Function
- “Meta-analysis of prospective studies of red meat consumption and colorectal cancer,” European Journal of Cancer Prevention
- “Processed and Unprocessed Red Meat and Risk of Colorectal Cancer: Analysis by Tumor Location and Modification by Time,” PLOS ONE
- “Red meat and colorectal cancer: a critical summary of prospective epidemiologic studies,” Obesity Reviews
- “Red and processed meat consumption and the risk of esophageal and gastric cancer subtypes in The Netherlands Cohort Study,” Annals of Oncology
- “Meat consumption and cancer risk: a case-control study in Uruguay,” Asian Pacific Journal of Cancer Prevention
- “Fruits, vegetables and the risk of cancer: a multisite case-control study in Uruguay,” Asian Pacific Journal of Cancer Prevention
- “Red Meat and Colorectal Cancer: A Quantitative Update on the State of the Epidemiologic Science,” The Journal of the American College of Nutrition
- “Human uptake and incorporation of an immunogenic nonhuman dietary sialic acid,” PNAS
- “Cardiovascular disease in the masai,” Atherosclerosis
- “Daily energy expenditure and cardiovascular risk in Masai, rural and urban Bantu Tanzanians,” British Journal of Sports Medicine
- “Heme Iron from Meat and Risk of Colorectal Cancer: A Meta-analysis and a Review of the Mechanisms Involved,” Cancer Prevention Research
- “Green vegetables, red meat and colon cancer: chlorophyll prevents the cytotoxic and hyperproliferative effects of haem in rat colon,” Carcinogenesis
- “Heme Iron Intake, Dietary Antioxidant Capacity, and Risk of Colorectal Adenomas in a Large Cohort Study of French Women,” Cancer Epidemiology, Biomarkers & Prevention
- “Total antioxidant potential of fruit and vegetables and risk of gastric cancer,” Gastroenterology
- “Dietary intake of heme iron and risk of cardiovascular disease: a dose-response meta-analysis of prospective cohort studies,” Nutrition, Metabolism and Cardiovascular Diseases
- “Gut Microbe-Generated TMAO from Dietary Choline Is Prothrombotic in Subjects,” Circulation
- “Effect of egg ingestion on trimethylamine-N-oxide production in humans: a randomized, controlled, dose-response study,” The American Journal of Clinical Nutrition
- “Dietary precursors of trimethylamine in man: a pilot study,” Food and Chemical Toxicology
- “Intestinal Microbial Metabolism of Phosphatidylcholine and Cardiovascular Risk,” The New England Journal of Medicine
- “Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis,” Nature Medicine
- “Metabolic, Epigenetic, and Transgenerational Effects of Gut Bacterial Choline Consumption,” Cell Host Microbe
- “Blood Trimethylamine-N-Oxide Originates from Microbiota Mediated Breakdown of Phosphatidylcholine and Absorption from Small Intestine,” PLOS ONE
- “A Paleolithic diet lowers resistant starch intake but does not affect serum trimethylamine-N-oxide concentrations in healthy women,” British Journal of Nutrition
- “Purification and comparison of liver microsomal flavin-containing monooxygenase from normal and streptozotocin-diabetic rats,” Biochemical Pharmacology
- Frequently Asked Questions about GFR Estimates, National Kidney Foundation
- Prediabetes: Your Chance to Prevent Type 2 Diabetes, CDC
- About Diabetes, CDC
- “Egg consumption and risk of coronary heart disease and stroke: dose-response meta-analysis of prospective cohort studies,” BMJ (Clinical Research Edition)
- “Egg consumption and CHD and stroke mortality: a prospective study of US adults,” Public Health Nutrition
- “Intake of animal products and stroke mortality in the Hiroshima/Nagasaki Life Span Study,” International Journal of Epidemiology
- “Effect of cruciferous vegetable consumption on heterocyclic aromatic amine metabolism in man,” Carcinogenesis
- “Effect of marinades on the formation of heterocyclic amines in grilled beef steaks,” Journal of Food Science
- “Reduced Dietary Intake of Carbohydrates by Obese Subjects Results in Decreased Concentrations of Butyrate and Butyrate-Producing Bacteria in Feces,” Applied and Environmental Microbiology
- “High-protein, reduced-carbohydrate weight-loss diets promote metabolite profiles likely to be detrimental to colonic health,” The American Journal of Clinical Nutrition
- “Gut microbiome response to a modern Paleolithic diet in a Western lifestyle context,” PLOS ONE
- “Starving our Microbial Self: The Deleterious Consequences of a Diet Deficient in Microbiota-Accessible Carbohydrates,” Cell Metabolism
- “Dietary risk factors for colon cancer in a low-risk population,” American Journal of Epidemiology
- “Poultry and Fish Consumption in Relation to Total Cancer Mortality: A Meta-Analysis of Prospective Studies,” Nutrition and Cancer
- “Does the American Cancer Society Promote Meat?” American Cancer Society
- “Dairy product consumption and development of cancer: an overview of reviews,” BMJ Open
- “Comprehensive Review of the Impact of Dairy Foods and Dairy Fat on Cardiometabolic Risk,” Advances in Nutrition
- “The relationship between high-fat dairy consumption and obesity, cardiovascular, and metabolic disease,” European Journal of Nutrition
- “Production-related contaminants (pesticides, antibiotics and hormones) in organic and conventionally produced milk samples sold in the USA,” Public Health Nutrition
- “Dairy products and inflammation: A review of the clinical evidence,” Critical Reviews in Food Science and Nutrition
- “Decrease of postprandial endothelial dysfunction by spice mix added to high-fat hamburger meat in men with Type 2 diabetes mellitus,” Diabetic Medicine
- “Antioxidant-rich spice added to hamburger meat during cooking results in reduced meat, plasma, and urine malondialdehyde concentrations,” The American Journal of Clinical Nutrition
- “Dietary proteins improve endothelial function under fasting conditions but not in the postprandial state, with no effects on markers of low-grade inflammation,” The British Journal of Nutrition
- “Increased Lean Red Meat Intake Does Not Elevate Markers of Oxidative Stress and Inflammation in Humans,” The Journal of Nutrition
- “An oily fish diet increases insulin sensitivity compared to a red meat diet in young iron-deficient women,” The British Journal of Nutrition
- “Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study,” Cardiovascular Diabetology
- “Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial,” The European Journal of Clinical Nutrition
- “Randomized controlled trials investigating the relationship between dietary pattern and high-sensitivity C-reactive protein: a systematic review,” Nutrition Reviews
- “Effects of a Paleolithic Diet on Cardiovascular Disease Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials,” Advances in Nutrition
- “Paleolithic and Mediterranean Diet Pattern Scores Are Inversely Associated with Biomarkers of Inflammation and Oxidative Balance in Adults,” The Journal of Nutrition
- “Attenuated Low-Grade Inflammation Following Long-Term Dietary Intervention in Postmenopausal Women with Obesity,” Obesity
- “Effects of dietary carbohydrate restriction versus low-fat diet on flow-mediated dilation,” Metabolism: Clinical and Experimental
- “Effects of weight loss on a low-carbohydrate diet on flow-mediated dilatation, adhesion molecules and adiponectin,” The British Journal of Nutrition
- “Acute Hyperglycemia Impairs Vascular Function in Healthy and Cardiometabolic Diseased Subjects: Systematic Review and Meta-Analysis,” Arteriosclerosis, Thrombosis, and Vascular Biology
- “Adaptation of β-Cell and Endothelial Function to Carbohydrate Loading: Influence of Insulin Resistance,” Diabetes
- “Mediterranean diet and erectile dysfunction: a current perspective,” Central European Journal of Urology
- “Erectile Dysfunction Precedes Coronary Artery Endothelial Dysfunction in Rats Fed a High-Fat, High-Sucrose, Western Pattern Diet,” The Journal of Sexual Medicine
- “Dietary flavonoid intake and incidence of erectile dysfunction,” The American Journal of Clinical Nutrition
- “Association Between Cardiovascular Health and Endothelial Function With Future Erectile Dysfunction: The Multi-Ethnic Study of Atherosclerosis,” American Journal of Hypertension
- “Menstrual differences due to vegetarian and nonvegetarian diets,” The American Journal of Clinical Nutrition
- “Vegetarianism and menstrual cycle disturbances: is there an association?,” The American Journal of Clinical Nutrition
- “Association between vegetarian diet and menstrual problems in young women: a case presentation and brief review,” Journal of Pediatric and Adolescent Gynecology
- “Dieting influences the menstrual cycle: vegetarian versus nonvegetarian diet,” Fertility and Sterility
- “Food intake diet and sperm characteristics in a blue zone: a Loma Linda Study,” European Journal of Obstetrics & Gynecology and Reproductive Biology
- “Vegan–vegetarian diets in pregnancy: danger or panacea? A systematic narrative review,” BJOG
- “Is vegetarianism healthy for children?” Critical Reviews in Food Science and Nutrition
- “Characterization of the receptor for transcobalamin II isolated from human placenta,” The Journal of Biological Chemistry
- “Transport and endogenous release of vitamin B12 in the dually perfused human placenta,” The Journal of Pediatrics
- “Determinants of cobalamin status in newborns,” Pediatrics
- “Increased urinary methylmalonic acid excretion in breast-fed infants of vegetarian mothers and identification of an acceptable dietary source of vitamin B-12,” The American Journal of Clinical Nutrition
- “Vitamin B-12: low milk concentrations are related to low serum concentrations in vegetarian women and to methylmalonic aciduria in their infants,” The American Journal of Clinical Nutrition
- “Increased risk of vitamin B-12 and iron deficiency in infants on macrobiotic diets,” The American Journal of Clinical Nutrition
- “Macrobiotic nutrition and child health: results of a population-based, mixed-longitudinal cohort study in The Netherlands,” The American Journal of Clinical Nutrition
- “Methylmalonic acid and homocysteine in plasma as indicators of functional cobalamin deficiency in infants on macrobiotic diets,” Pediatric Research
- “Vitamin B-12 status in a macrobiotic community,” The American Journal of Clinical Nutrition
- “High prevalence of cobalamin deficiency in Guatemalan schoolchildren: associations with low plasma holotranscobalamin II and elevated serum methylmalonic acid and plasma homocysteine concentrations,” The American Journal of Clinical Nutrition
- “Risk of persistent cobalamin deficiency in adolescents fed a macrobiotic diet in early life,” The American Journal of Clinical Nutrition
- “Risk of persistent cobalamin deficiency in adolescents fed a macrobiotic diet in early life,” The American Journal of Clinical Nutrition
- “Signs of impaired cognitive function in adolescents with marginal cobalamin status,” The American Journal of Clinical Nutrition
- “Low bone mineral density and bone mineral content are associated with low cobalamin status in adolescents,” European Journal of Nutrition
- “A vitamin B-12 supplement of 500 μg/d for eight weeks does not normalize urinary methylmalonic acid or other biomarkers of vitamin B-12 status in elderly people with moderately poor vitamin B-12 status,” The Journal of Nutrition
- “Culled males, infant mortality and reproductive success in a pre-industrial Finnish population,” Proceedings of the Royal Society B
- “Changes in Income at Macro Level Predict Sex Ratio at Birth in OECD Countries,” PLOS ONE
- “Vegetarian diets. Are they good for pregnant women and their babies?” The Practising Midwife
- “Persistence of neurological damage induced by dietary vitamin B-12 deficiency in infancy,” Archives of Disease in Childhood
- “Severe vitamin B12 deficiency in an exclusively breastfed 5-month-old Italian infant born to a mother receiving multivitamin supplementation during pregnancy,” BMC Pediatrics
- “Dietary intake and nutritional status of vegetarian and omnivorous preschool children and their parents in Taiwan,” Nutrition Research
- “Long-chain n-3 PUFA in vegetarian women: a metabolic perspective,” Journal of Nutritional Science
Research on Animal Foods and Conflicts of Interest
Another claim made in the film is that recent research exonerating cholesterol, saturated fat, and red meat is tainted because it’s funded by the meat, egg, and dairy industry. I’ve long argued that corporate funding of medical research is a problem. But it’s not just by the meat, egg, and dairy industry—the Big Food lobby that supports processed and refined foods like sugar and industrial seed oils is far larger. Historically, the sugar lobby paid for research in the 1960s with the goal of pointing the finger at fat, rather than sugar, as the primary driver of cardiovascular disease.
In fact, virtually all the medical experts in The Game Changers profit from selling books, supplements, or other products related to the vegan diet. Conflicts of interest go both ways, but the film doesn’t make any mention of this.
For more:
References and resources:
- “Sugar Industry and Coronary Heart Disease Research: A Historical Analysis of Internal Industry Documents,” JAMA Internal Medicine
- “Food Industry Funding of Nutrition Research: The Relevance of History for Current Debates,” JAMA Internal Medicine
- “My Debate with David Katz,” Nina Teicholz
Is Veganism the “Natural” Human Diet?
One of the most preposterous claims in The Game Changers is that Paleolithic humans ate mostly plants. This is literally rewriting history, and it goes against what virtually all respectable anthropologists believe. Our hominid ancestors have been eating meat for at least 2.5 million years. There is also wide agreement that going even further back in time, our primate ancestors likely ate a diet similar to that of modern chimps, which we now know eat vertebrates.
It is true that we can’t know with certainty the exact proportion of animal foods vs. plants that our Paleolithic ancestors ate. That said, the archeological record provides strong evidence that animal products played a critical role in human evolution. The fossil record clearly indicates a strong history of animal product consumption in humans from 130,000 to 13,000 years ago.
For more:
- “What Is an Ancestral Diet and How Does It Help You?” Chris Kresser
- “What Is the Optimal Human Diet?” Chris Kresser
References and resources:
- “Environment and behavior of 2.5-million-year-old Bouri hominids,” Science
- “Stable isotope evidence of meat eating and hunting specialization in adult male chimpanzees,” PNAS
- The Story of the Human Body: Evolution, Health, and Disease, Daniel E. Lieberman
- “Isotopic biogeochemistry (13C,15N) of fossil vertebrate collagen: application to the study of a past food web including Neandertal man,” Journal of Human Evolution
- “Effect of diet, physiology and climate on carbon and nitrogen stable isotopes of collagen in a late pleistocene anthropic palaeoecosystem: Marillac, Charente, France,” Journal of Archaeological Science
- “Palaeoenvironmental and Palaeodietary Implications of Isotopic Biogeochemistry of Last Interglacial Neanderthal and Mammal Bones in Scladina Cave (Belgium),” Journal of Archaeological Science
- “Stable isotopes and the seasonality of the Oronsay middens,” Antiquity
- “A brief review of the archaeological evidence for Palaeolithic and Neolithic subsistence,” The European Journal of Clinical Nutrition
- “Neanderthal diet at Vindija and Neanderthal predation: the evidence from stable isotopes,” PNAS
- “Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets,” The American Journal of Clinical Nutrition
- “The paradoxical nature of hunter-gatherer diets: meat-based, yet non-atherogenic,” The European Journal of Clinical Nutrition
Will a Plant-Based Diet Save the World?
Several common, yet inaccurate, claims about the environmental impacts of animal foods are made in The Game Changers, like:
- Producing meat takes up too much farmland and cropland, and that livestock consume valuable food/calories that could be used to feed humans
- Livestock are responsible for a large percentage of greenhouse gas emissions
- Shifting to a plant-based diet would have a significant impact on greenhouse gas emissions and would free up land that could be used to grow crops
In reality, most of the land that is used to cultivate livestock is suitable only for grazing. It could not be used for crop production. And most livestock feed is not grown specifically for livestock—it is a byproduct of food overproduction processes. Eliminating livestock wouldn’t increase the food supply for humans.
When it comes to greenhouse gasses, the common statistics cited reflect the environmental impact of industrial beef production, not regenerative agriculture. While I do agree with plant-based diet advocates that our current concentrated animal feeding operation (CAFO) system for producing beef and other animal foods is problematic, where we disagree is on the solution. They propose eliminating animal foods from the diet; I propose regenerative agriculture that includes grass-fed meat.
Our soils are rapidly deteriorating due to erosion, nutrient depletion, and loss of organic carbon. We desperately need new methods of restoring healthy soil, and regenerative, holistically managed livestock is a time-tested and proven method. This means converting cropland used for livestock to grassland and allowing livestock to graze there. Grass-fed cattle can actually sequester carbon from the atmosphere, meaning they can be either net-carbon neutral or even act as a carbon sink.
For more:
References and resources:
- Articles and Infographics, Sacred Cow
- “Livestock on grazing lands,” Livestock and the Environment. Meeting the Challenge
- “Changes in consumption of omega-3 and omega-6 fatty acids in the United States during the 20th century,” The American Journal of Clinical Nutrition
- “Omega-6 and omega-3 oxylipins are implicated in soybean oil-induced obesity in mice,” Scientific Reports
- “Livestock: On our plates or eating at our table? A new analysis of the feed/food debate,” Global Food Security
- Sources of Greenhouse Gas Emissions, EPA
- “Grazing management that regenerates ecosystem function and grazingland livelihoods,” African Journal of Range & Forage Science
- “Forages and Pastures Symposium: Cover Crops in Livestock Production: Whole-System Approach: Managing grazing to restore soil health and farm livelihoods,” Journal of Animal Science
- “Nutritional and greenhouse gas impacts of removing animals from US agriculture,” PNAS
- “The bioavailability of iron, zinc, protein and vitamin A is highly variable in French individual diets: Impact on nutrient inadequacy assessment and relation with the animal-to-plant ratio of diets,” Food Chemistry
- “The Protein-Leverage Hypothesis: Do We Keep Eating Until We Get Enough Protein?” Darwinian Medicine
- “Do low-carbon-emission diets lead to higher nutritional quality and positive health outcomes? A systematic review of the literature,” Public Health Nutrition
- “Carbon Footprint Evaluation of Regenerative Grazing at White Oak Pastures: Results Presentation,” White Oak Pastures
- “Response to FDA Questions- GRAS Notice 540 Soybean leghemoglobin- Impossible Foods, Inc.,” FDA
- “Is “Food-Tech” the Future of Food?” Medium
- “Why Fake Burgers Make No Sense,” Sustainable Dish, Diana Rodgers, RD
- “Field Deaths in Plant Agriculture,” Journal of Agricultural and Environmental Ethics
- “Soils are endangered, but the degradation can be rolled back,” Food and Agriculture Organization of the United Nations
- Science Library, Savory Institute
The Game Changers Debate with James Wilks
The Game Changers follows James Wilks, a combative instructor for the U.S. military and a former UFC fighter, as he converts to a vegan diet while sports stars, celebrities, doctors, and medical experts weigh in. They claim that a plant-based diet is optimal, especially for athletic performance, while animal products are harmful to health.
Even though it may be possible for some athletes to thrive on a plant-based diet, extensive research and my own clinical experience suggest that a vegan diet is not optimal for most people. The Game Changers relies on propaganda, sloppy or misleading science, and a lack of context to support its core argument, but I would like to set the record straight. That’s why I returned to the Joe Rogan Experience to debate James Wilks on this topic.
For more:
- “Why Eating Meat Is Good for You,” Chris Kresser
- “Why You Should Eat Meat: My Appearance on the Joe Rogan Experience,” Chris Kresser
- “What Is an Ancestral Diet and How Does It Help You?” Chris Kresser
- “What Is the Optimal Human Diet?” Chris Kresser
References and resources:
- “Plasma and blood viscosity in the prediction of cardiovascular disease and mortality in the Scottish Heart Health Extended Cohort Study,” European Journal of Preventative Cardiology
- “Effects of a Paleolithic Diet on Cardiovascular Disease Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials,” Advances in Nutrition
- “Systematic Review and Meta-Analysis of Clinical Trials of the Effects of Low Carbohydrate Diets on Cardiovascular Risk Factors,” Obesity Reviews
- “Effect of a Single High-Fat Meal on Endothelial Function in Healthy Subjects,” The American Journal of Cardiology
- “Effect of Antioxidant Vitamins on the Transient Impairment of Endothelium-Dependent Brachial Artery Vasoactivity Following a Single High-Fat Meal,” JAMA
- “The Postprandial Appearance of Features of Cardiometabolic Risk: Acute Induction and Prevention by Nutrients and Other Dietary Substances,” Nutrients
- “Endothelial Dysfunction in Diabetes: The role of reparatory mechanisms,” Diabetes Care
- “Low-Fat Milk Ingestion Prevents Postprandial Hyperglycemia-Mediated Impairments in Vascular Endothelial Function in Obese Individuals with Metabolic Syndrome,” The Journal of Nutrition
- “Mediterranean Dietary Pattern, Inflammation and Endothelial Function: A Systematic Review and Meta-Analysis of Intervention Trials,” Nutrition, Metabolism, and Cardiovascular Diseases
- “Influence of food patterns on endothelial biomarkers: a systematic review,” The Journal of Clinical Hypertension
- “Dietary proteins improve endothelial function under fasting conditions but not in the postprandial state, with no effects on markers of low-grade inflammation,” The British Journal of Nutrition
- “Endothelial dysfunction induced by postprandial lipemia is neutralized by addition of proteins to the fatty meal,” Atherosclerosis
- “Metabolic and Vascular Effect of the Mediterranean Diet,” International Journal of Molecular Sciences
- “Advancing Beyond the ‘Heart-Healthy Diet’ for Peripheral Arterial Disease,” Journal of Vascular Surgery
- “Effect of carbohydrate restriction-induced weight loss on aortic pulse wave velocity in overweight men and women,” Applied Physiology Nutrition and Metabolism
- “Paleolithic and Mediterranean Diet Pattern Scores Are Inversely Associated with Biomarkers of Inflammation and Oxidative Balance in Adults,” The Journal of Nutrition
- “Attenuated Low-Grade Inflammation Following Long-Term Dietary Intervention in Postmenopausal Women with Obesity,” Obesity
- “Dietary proteins improve endothelial function under fasting conditions but not in the postprandial state, with no effects on markers of low-grade inflammation,” The British Journal of Nutrition
- “Increased Lean Red Meat Intake Does Not Elevate Markers of Oxidative Stress and Inflammation in Humans,” The Journal of Nutrition
- “An oily fish diet increases insulin sensitivity compared to a red meat diet in young iron-deficient women,” The British Journal of Nutrition
- “Short-Term Mediterranean Diet Improves Endurance Exercise Performance: A Randomized-Sequence Crossover Trial,” Journal of the American College of Nutrition
- “Ketogenic diet benefits body composition and well-being but not performance in a pilot case study of New Zealand endurance athletes,” The Journal of the International Society of Sports Nutrition
- “The Effects of a Ketogenic Diet on Exercise Metabolism and Physical Performance in Off-Road Cyclists,” Nutrients
- “Effects of a 12-Week Very-Low Carbohydrate High-Fat Diet on Maximal Aerobic Capacity, High-Intensity Intermittent Exercise, and Cardiac Autonomic Regulation: Non-randomized Parallel-Group Study,” Frontiers in Physiology
- “A Low-Carbohydrate Ketogenic Diet Reduces Body Mass Without Compromising Performance in Powerlifting and Olympic Weightlifting Athletes,” The Journal of Strength & Conditioning Research
- “The Three-Month Effects of a Ketogenic Diet on Body Composition, Blood Parameters, and Performance Metrics in CrossFit Trainees: A Pilot Study,” Sports
- “Effects of a 4-Week Very Low-Carbohydrate Diet on High-Intensity Interval Training Responses,” Journal of Sports Science and Medicine
- “Kill scientists, says animal rights chief,” The Guardian
- “Atkins Under Attack,” Newsweek
- “‘How Not to Die’ by Dr. Michael Greger: A Critical Review,” Healthline
- “Sugar Industry and Coronary Heart Disease Research: A Historical Analysis of Internal Industry Documents,” JAMA Internal Medicine