Educational information, not medical advice — ask your doctor or midwife.
PSP stands for Polysaccharide Peptide — a bioactive compound isolated from the Turkey Tail mushroom (Trametes versicolor), a shelf-like fungus found growing on dead wood across forests worldwide. It is closely related to PSK (also called Krestin), another extract from the same mushroom that has been an approved cancer adjunct therapy in Japan since the 1970s. PSP differs slightly in its protein component and is the more studied form in Chinese clinical research.
PSP works primarily by activating and amplifying the body's own immune defenses. It binds to receptors on immune cells — especially natural killer cells, T-cells, and macrophages — essentially training them to be more alert and responsive. It also appears to support a healthier gut microbiome, which in turn influences immune regulation throughout the body.
Hot water extraction is the traditional and most clinically studied preparation method, as beta-glucans are water-soluble. Capsules and powders using standardized hot water extracts are most reliable. Look for products specifying PSP content or beta-glucan percentage. Raw or unextracted mushroom powder delivers far lower active compound levels and is not equivalent to a clinical extract.
Turkey Tail mushroom has been used in Chinese herbal medicine (known as Yun Zhi) for centuries, traditionally as a tonic to support vitality and lung health. Modern scientific interest intensified in Japan in the 1970s when PSK was isolated and became a government-approved cancer therapy. Chinese researchers subsequently isolated PSP in the 1980s, and it has since been the subject of dozens of controlled clinical trials, particularly in cancer care.
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