A functional unit of your gastrointestinal system, organized as a multi-layer system, made up of two main components: a physical barrier surface and a deep functional barrier. The gut barrier is able to discriminate between pathogens and commensal microorganisms, organizing the immune tolerance and the immune response to pathogens. From the outer layer to the inner layer, the physical barrier is composed of gut microbiota, mucus, epithelial cells, and the innate and adaptive immune cells forming the gut-associated lymphoid tissue.

With over 100 times the surface area of your skin (seriously, it’s the equivalent of two tennis courts and thickness of one cell wall, or half a human hair), the gut is the largest exposed external surface on your body. On a daily basis, it deals with the food you eat, the molecules you inhale, and at times, the potential toxins that are in our food, air, and water. If your intestinal lining is damaged or compromised (you’ve probably heard of this being referred to as ‘leaky gut’), substances that don’t belong in your body can enter the bloodstream, triggering various reactions including inflammation, allergies, irritable bowels, migraines, pain, and fatigue.

Your gut barrier has two jobs: to absorb beneficial nutrients and protect against harmful substances. The inner lining of your small and large intestines are merely one cell thick (that’s about half a human hair!). Beneficial bacteria take up space along your epithelial wall and its mucus lining, maintaining your gut barrier integrity.