When sourcing Ganoderma, the most critical factor is the active ingredient content, specifically Polysaccharides and Triterpenoids. High-quality extracts should typically contain at least 10-30% Polysaccharides. Additionally, verify the cultivation method; Ganoderma grown on natural wood logs (Duanmu) is generally superior in nutrient density compared to those grown on grain or sawdust substrates. Ensure the product is free from heavy metals (Lead, Arsenic, Mercury) and pesticide residues, which are common risks in herbal supplements.