30 Years of Diet Trials: What Matters Most in Keto, Vegan & Mediterranean Diet | Christopher Gardner

Visit The Proof website for the full show notes and supporting studies: https://theproof.com/podcast/ Simon's personal supplement stack: https://hub.theproof.com/supplements Most of the arguments people have about diet are fought over questions the science will never settle, because the study that would settle them cannot be run. You cannot randomise people to keto or vegan and follow them for 30 years. Christopher Gardner has spent his career working inside that limitation, and in this episode he explains what it means for the choices you make at the supermarket. Christopher Gardner, PhD, is a nutrition scientist at Stanford, director of the Stanford Nutrition Studies Research Group, past chair of the American Heart Association's Nutrition Committee, and a recent member of the 2025 US Dietary Guidelines Advisory Committee. He has run more than 20 human diet trials over 30 years, and has just written Food Sense: What to Eat and Why. In this conversation we cover: - Why the definitive diet trial will never be run, and how to read the evidence we actually have - The $1.4 million garlic study that found nothing, and why a null result can be the most useful finding in a paper - Data dredging, pre-registration, and what really happened with his fermented food study - The four things every popular diet agrees on, and the six foods that divide them - His keto versus Mediterranean trial, and the two results that went in opposite directions - How he reads new studies that contradict his own position, including Sam Klein's ketogenic diet trial - Why he is now focused on hospital, university, and military kitchens rather than randomised trials 00:00 Philosophy and Nutrition Science 07:04 Does Garlic Lower Cholesterol? 17:34 Why Long Diet Trials Never Happen 29:43 Do Calcium Supplements Prevent Fractures? 34:43 Fermented Foods and Gut Health 42:44 Gut Microbiome Supplements: Hype vs Science 56:52 How to Stick to a Healthy Diet 01:03:43 Are Beans, Fruit, and Eggs Healthy? 01:14:24 Keto vs Mediterranean for Cholesterol 01:23:02 3 Diets Compared: LDL Results 01:34:40 Vegan Diet and Muscle Loss 01:42:28 How to Fix the Food System 01:51:49 Eating for the Planet and Animals To connect with Christopher Gardner, visit https://med.stanford.edu/nutrition, pick up a copy of his new book at https://www.simonandschuster.com/books/Food-Sense/Christopher-Gardner/9781668077184, or find him on Instagramhttps://www.instagram.com/cgardnerphd/?hl=en and https://www.linkedin.com/in/christopher-gardner-phd/. Support the show: The best way to support the show is to use the products and services offered by our sponsors. Visit http://theproof.com/friends for exclusive discounts. If you have any additional questions you would like answered in the future, let me know in the comments. Enjoy, friends. Simon This episode is brought to you by: 38TERA 38TERA’s BDR is a clinically dosed gut health supplement for improved digestion, less bloating, better bowel movements and a healthier microbiome. Head to https://38tera.com/?ref=SIMON and use code THEPROOF for a discount at checkout. 38Tera ships to the United States, Australia, and New Zealand. IM8 With 92 nutrients, including Vitamin B12, Iodine, Selenium and Vitamin D, in highly absorbable forms, IM8 Daily Essentials is the perfect all-in-one daily multi-vitamin to ensure you meet your daily micronutrient needs. IM8 is offering an exclusive 10% off your first order with a free welcome kit when you enter the promo code SIMON at checkout on http://im8health.com/. IM8 ships to 27 countries including the U.S., Canada, the U.K., Australia, and many regions across Europe, Asia, and South America. Function Health Take charge of your health with advanced blood testing and personalised insights. Function Health offers a practical way to track key health markers such as cholesterol, blood sugar, and more. Learn more and join at http://functionhealth.com/simonhill for a $25 credit toward your membership. Only available to those living in the United States. Function Health ships to 48 U.S. states, excluding Rhode Island, Hawai‘i, and Puerto Rico. Shopify Shopify, the world's leading e-commerce platform, helps you turn browsers into buyers with the internet’s best-converting check out–up to 36% better compared to other leading e-commerce platforms. To boost your conversion rate, and grow your business, sign up for a one-dollar-per-month trial period at https://www.shopify.com/proof. WHOOP Whoop, the most advanced fitness and health wearable available. Your personalised fitness and health coach to recover faster, sleep better, and train smarter. Claim your first month free on http://join.whoop.com/simon. Whoop ships to 56+ international markets, including the US, Canada, most of Europe, Australia, New Zealand, UAE, Singapore, and parts of Asia.