Polysaccharides from two Lentinus mushrooms, L. polychrous and L. squarrosulus, survived the digestive tract 70–81% intact and went on to feed beneficial gut bacteria while crowding out harmful ones. This flipped key gut ratios in a healthy direction — Firmicutes/Bacteroidota dropped from 1.47 to 0.60, Blautia/Bacteroides from 1.43 to 0.13 — both linked to lower obesity and disease risk. Fermentation also dropped pH from 7.2 to 5.75, a sign the bacteria were actively producing the short-chain fatty acids that support gut, brain, and heart health.