Not all mushroom supplements are created equal. This deep dive into mushroom beta-glucans—the key immune-supporting compounds—found that structure is everything. The most effective forms had a triple helix shape, high molecular weight (over 1,000 kDa), and specific sugar linkages (3→1 and 6→1). Mushrooms like maitake (Grifola frondosa), reishi (Ganoderma lucidum), and shiitake (Lentinula edodes) scored highest for immune benefits when their beta-glucans had a branching ratio between 0.2–0.4 and chain lengths over 25 units. These compounds triggered strong increases in immune signals. But watch how they’re processed—harsh extraction methods can flatten their structure and lower effectiveness.