The lining of the gut is called the Epithelial and it performs a variety of functions that includes, absorption, secretion, excretion, filtration, diffusion, and sensory reception but one of its main jobs is as the protective layer which acts as a barrier to prevent pathogens and harmful substances entering your bloodstream while allowing water and nutrients through. The epithelium is coated in a protein mucus layer which needs a healthy and diverse microbiome to support it. It’s a kind of living co-operative. The gut lining has small gaps between the cells, just big enough to allow nutrients to pass from the intestine through to the bloodstream. These gaps, or tight junctions, control the permeability of your intestine.
Scientists believe that under some health conditions, these gaps become larger. Any compromise of that protective layer can result in harmful substances like bacteria, poorly digested food particles and toxins getting through. These substances can be seen as a threat by the body and can trigger an immune reaction which leads to inflammation.