Nutritional supplements based on the mycelia and extracts of specific mushroom species with medicinal properties are used as immune boosters.
The exact mechanisms of action of mushroom extracts in the body are not yet fully understood but research suggests that they promote immunity in a variety of ways. Studies have demonstrated the ability of certain mushroom extracts to support natural killer (NK) cell, T-lymphocyte, and macrophage activity, as well as promoting cytokine production.
The most studied mushroom extracts and those most commonly found in nutritional supplements include Shiitake, Maitake, Reishi, and Portabella. Each have slightly different activity with studies showing Shiitake and Maitake are a rich source of beta glucan which helps the body modulate activity of NK cells, T-cells and macrophages. Reishi is a rich source of polysaccharides that stimulate macrophages and enhance T-cell proliferation. Portabella is thought to stimulate immune activity by increasing T-cell health and function.