Oyster mushroom is a widely grown edible fungus that people use as food and in concentrated supplements. Capsules of dried powder or extract are the most common supplemental forms. Many also cook with the fresh mushrooms directly.
This mushroom supplies beta-glucans and other polysaccharides that support normal immune defenses. Because these compounds can shift immune activity, anyone taking immune-modulating medications should be cautious with concentrated extracts.
Oyster mushroom can affect how the body manages blood sugar. If you take medications for glucose control, check with your healthcare provider before adding an extract. Whole food amounts are generally fine for most people.