113. Dr. Karan Rajan: Why Gut Health Shapes Your Longevity

You can eat healthy, exercise daily, and still struggle with fatigue, inflammation, or brain fog. Why? Because every system in your body is connected. The gut, brain, and immune system are constantly communicating, and most health plans ignore that network. In this episode of Extend, I sit down with Dr. Karan Rajan to explore how the gut microbiome shapes everything from digestion and immunity to mood, skin, and longevity. We unpack the science behind leaky gut, fiber diversity, fermented foods, and the connection between microbiome imbalance and chronic inflammation. We also dive into practical steps such as how to feed all three layers of your colon, the right way to use fiber supplements, the truth about probiotics, and how daily habits like sleep timing, stress, and even phone use in the bathroom affect gut health. Dr. Karan Rajan is a surgeon, educator, and gut health expert with more than five million followers across social media. His research in microbiome science and human health has made him one of the most trusted voices translating complex medicine into actionable steps for modern life. What's Discussed: (00:00) From Surgery to the Science of the Microbiome (05:18) How Fiber Diversity Fuels a Healthy Gut (12:14) The Link Between Leaky Gut, Skin, and Inflammation (19:49) What Destroys the Microbiome and How to Rebuild It (27:56) Poop, Circadian Rhythms, and Real Gut Health Markers (40:13) Fiber Supplements, Fermented Foods, and Smart Probiotics (54:05) Inside the Future of Gut Health and the Loam Project Thank You to Our Sponsors: IM8: Try IM8 today with a 30-day money back guarantee. You can get 10% off your first order with code DRSHAH at https://im8health.com/discount/DRSHAH . Pendulum: Go to pendulumlife.com and use code EXTEND at checkout for 20% off all Pendulum membership first orders. Learn more about Dr. Shah: Website: https://www.drshah.com/ Clinic: https://www.next-health.com/ Instagram: @darshanshahmd Learn more about Dr. Karan Rajan: Instagram: drkaranrajan YouTube: Dr Karan Linkedin: Dr Karan Rajan LOAM: www.loamscience.com