Gut health is one of the most-discussed and least-understood areas in modern nutrition. Walk into any health food shop and you’ll see entire walls of probiotic supplements, prebiotic powders, and gut-restore formulas — most making claims the science doesn’t support. Meanwhile, the genuinely high-value interventions are mostly free and sit in your supermarket’s produce section. This is the working guide a qualified nutritionist uses with clients: what prebiotics and probiotics actually are, where the evidence is strong, and the food-first framework that does most of the work before any supplement enters the picture.