Dietary habits may result in an altered susceptibility to IBD in a variety of ways; it has been proven that food components can modify intestinal permeability (e.g., short chain fatty acids—SCFAs, vitamin D, vitamin A, zinc, cysteine, methionine, glutamine, tryptophan and arginine decrease intestinal permeability, while gluten, glucose, fructose, fats, ethanol and emulsifiers increase it) and can serve as ligands for various receptors expressed in enterocytes (e.g., farnesoid X receptor, aryl hydrocarbon receptor, pregnane X receptor, and specific G protein-coupled receptors) [30,31]. This evidence concerns the gene AHR and irritable bowel syndrome.