Edible mushrooms contain β-glucans, chitin, polyphenols, and trehalose that resist digestion and feed gut microbes, increasing short-chain fatty acids like acetate, propionate, and butyrate. These metabolites support intestinal barrier strength, immune balance, inflammation control, and metabolic health through everyday foods like shiitake (Lentinula edodes), reishi (Ganoderma lucidum), lion’s mane (Hericium erinaceus), and cordyceps (Cordyceps militaris). The biggest gap is human data, since most evidence still comes from in vitro and animal research, but the gut-health pathway is one of the strongest functional mushroom angles.