The Small Intestine Code: Leaky Gut, SIBO, and the Gut-Brain Axis

our small intestine does far more than digest food.In episode 4 of our Organ Series, Dr. Jace and Dr. Addy explore the small intestine, leaky gut, SIBO, absorption, intestinal permeability, the gut-brain axis, serotonin production, microbiome signaling, and how gut health can influence inflammation, mood, energy, and nutrient status.The small intestine is the body’s main absorption site. It helps absorb amino acids, carbohydrates, fats, vitamins A, D, E, and K, iron, calcium, magnesium, zinc, and more. But when the gut lining becomes compromised, larger particles, inflammatory compounds, and bacterial byproducts may pass through the intestinal barrier and contribute to systemic symptoms.This episode breaks down the small intestine as a “border” system. When the fence breaks, we may see leaky gut. When the bacteria overgrow, we may see SIBO. When the gut-brain signal gets noisy, we may see symptoms that extend beyond digestion — including anxiety, depression, mood swings, fatigue, and inflammation.Dr. Jace and Dr. Addy also discuss practical strategies to support the small intestine, including removing processed foods and excess sugar, using bone broth and collagen, adding fermented foods gradually, improving sleep, managing stress, supporting nasal breathing, using L-glutamine, digestive enzymes, zinc carnosine, and working with the right provider for testing when symptoms become more serious.In this episode, we cover:The small intestine as the body’s main absorption organWhy absorption matters for nutrient statusLeaky gut and intestinal permeabilityTight junctions and the gut barrierGlyphosate, pesticides, gluten, and gut lining irritationFood sensitivities and “allergic to everything” patternsSIBO and bacterial overgrowthThe gut-brain axisThe vagus nerve and gut-to-brain communicationSerotonin production in the gutMood, anxiety, depression, and microbiome signalingProcessed food, excess sugar, and dysbiosisBone broth, collagen, and gut lining supportFermented foods and microbiome diversityKimchi, microplastics, and future gut researchSleep and intestinal repairStress and intestinal permeabilityL-glutamine for gut barrier supportDigestive enzymes for meal supportZinc carnosine and mucosal repairTargeted probiotics and microbiome mappingSIBO breath testing and stool analysisRed flags that require medical evaluationKey takeaway:You can eat healthy and still be malnourished if your small intestine is not absorbing properly.The goal is not just to eat better. The goal is to absorb better, protect the gut barrier, reduce inflammatory triggers, support the microbiome, and improve the gut-brain communication system.Follow The Functional Code:Instagram: https://www.instagram.com/thefunctionalcodeYouTube: https://www.youtube.com/@TheFunctionalCodeSpotify: https://open.spotify.com/show/3aY5zkhwg5Rzk2q33cbIlfApple Podcasts: https://podcasts.apple.com/us/podcast/the-functional-code-podcast/id1754585557Disclaimer: This podcast is for informational purposes only and is not intended as medical advice. Always consult a qualified healthcare provider.