Researchers tested whether medicinal residue—leftover from herbal supplement production—could replace sawdust in growing gray oyster mushrooms (Pleurotus ostreatus). The best results came from an 80:20 mix of medicinal residue to sawdust, producing larger, heavier mushrooms with up to 0.81% polysaccharides and 0.32% saponins. A full 100% replacement underperformed, suggesting sawdust helps maintain structure and aeration.