turkey tail

Turkey tail is a common shelf mushroom (Trametes versicolor, also called Coriolus versicolor) that grows on dead logs and is named for its brown-and-tan banding that resembles a turkey's tail feathers. In traditional Chinese medicine it is known as Yun Zhi, and in Japan as kawaratake. Its most-studied components are polysaccharides (including beta-glucans), and two specific extracts derived from it — PSK (polysaccharide-K) and PSP — account for most of the research. In the US it is sold as a dietary supplement in capsules, powders, and teas.

According to the NCI's PDQ patient-version summary on medicinal mushrooms, most clinical research is on PSK, a specific standardized extract used in Japan as an add-on to standard cancer chemotherapy — not on the over-the-counter turkey tail supplements sold in the US. In studies summarized by the NCI, some patients with gastric or colorectal cancer who received chemotherapy plus PSK were less likely to have a recurrence and lived longer, while breast-cancer studies looked mainly at immune-system markers (such as T-cell and B-cell levels) rather than survival or symptoms. These findings are specific to PSK as an adjunct to chemotherapy and do not establish that everyday turkey tail supplements have the same effects. Importantly, the FDA has not approved turkey tail or PSK to treat cancer or any other condition, and the available evidence does not support using turkey tail supplements as a stand-alone treatment for any disease.

There is no established or FDA-approved dose for turkey tail supplements. The NCI notes that the most-studied form, PSK, is a standardized product used in Japan and is not the same as a typical US supplement; PSK has been given in capsule form and as a tea. Commercial supplements vary widely in their content, and the NCI notes that turkey tail can be hard to tell apart from related Trametes mushrooms without special testing. Talk to your doctor or pharmacist before using turkey tail, especially if you have a medical condition, take medications, or are undergoing cancer treatment.

The NCI reports that PSK has been used in people in Japan for a long time and that few side effects have been reported. However, that record applies to the standardized PSK extract studied in supervised settings, not necessarily to the varied turkey tail supplements sold in the US, which are not tightly regulated for consistency. As a general precaution, anyone who is pregnant or breastfeeding, has an autoimmune condition or a compromised immune system, or is receiving cancer therapy should consult a clinician before use. Turkey tail should never replace conventional medical care.

The NCI states that few side effects have been reported in studies of PSK in Japan. Because over-the-counter turkey tail supplements differ from the studied PSK extract and are not tightly regulated, their full side-effect profile is not well characterized; mild digestive upset is possible. Stop use and seek medical advice if you have an adverse reaction.

The cited NCI source does not detail specific drug interactions for turkey tail. Because PSK has been studied as an addition to cancer chemotherapy, anyone undergoing cancer treatment or taking prescription medications should not add turkey tail to their regimen without medical guidance. As a theoretical caution, a supplement marketed for immune effects could conceivably interact with immunosuppressant drugs, so discuss any new supplement with your care team first.