Constituents

Ergosterol, polysaccharides, (1-3, 1-6)-ß-D-glucans

 

Pharmacology

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The majority of research that has been done on turkey tail has been focused on polysaccharide krestin (PSK) and polysaccharide peptide (PSP). These are both compounds with patented extraction methods and are not necessarily found in high amounts innately in the mushrooms.

 

Gut Microbiome. Turkey tail has demonstrated prebiotic-like activity in vitro and in vivo. In vitro research has shown that the fermentation of PSP extract by gut bacteria increases the beneficial bacteria Bifidobacterium and Lactobacillus spp. while reducing the less desirable bacteria, Clostridium difficile, Staphylococcus spp. and Enterococcus spp. This study also saw increased levels of lactate and beneficial short chain fatty acids (1).

 

Immune. PSK extract modulates the immune response through stimulation of both extracellular pattern recognition receptors (TLR2) and intracellular pathogen sensors (NLRP3 inflammasome) (2). There have been many peer-reviewed publications on the immune benefits of turkey tail extracts, including 37 in vitro articles, 55 animal studies, 43 published human clinical studies, and 11 review articles in gastrointestinal, breast, and lung immune dysregulation. In the last two years, five more PSK trials in colorectal cancer have been published. Trametes water extract is made up of 62% polysaccharide and 38% PSK. After ingestion, PSK is highly bioavailable and can be found in the bone marrow, salivary glands, brain, liver, spleen, and pancreas in mice and rabbits within 24 hours. Once absorbed, PSK induces cytokine modulation, increasing TNF-α, IFN-γ, IL-2 and IL-8 (3).

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It is important to note that PSK is a patented extract from a specific strain of Trametes versicolor and the PSK noted in these studies is not necessarily the same polysaccharide-protein that is found in the T. versicolor fruiting body. However, T. versicolor mushroom does contain other protein bound polysaccharides that likely have a similar function.

 

Current and traditional medicinal use

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History and Folk Use

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In traditional Chinese medicine, turkey tail is called Cloud Fungus. It is said to replenish essence and qi, and regulate immune function. Traditionally, it was used to invigorate spleen and eliminate dampness, arrest cough, and help with breathing difficulty.

 

Current research

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Microbiome. In a preclinical trial with 21 women, PSP gel was administered intravagninally. There was improved epithelialization of the cervical mucosa and the concentration of Lactobacillus increased 54.5% while the pH decreased from 4.2 to 4.09 (4).

 

In a randomized clinical trial, 1,200mg of PSP was administered three times a day on an empty stomach alongside the antibiotic amoxicillin. While amoxicillin alone led to an increase in Escherichia and Shigella, the PSP group had distinctive positive changes in the human microbiome, consistent with its activity as a prebiotic (5). 

 

Immune. In six randomized controlled trials, three grams a day of PSK or PSP alongside standard chemotherapy showed benefit on immune function, performance status and body weight, and overall survival. PSK increases immune surveillance and offsets chemotherapy-induced bone marrow toxicity, and reduces depression of immune cells and immune cell activity during chemotherapy. PSK also increases NK cells and phagocytic activity, reduces TGF-ß, and increases the antitumor response of peripheral blood mononuclear cells (6). 

 

In a randomized, double blind, placebo-controlled trial, patients reported better physical, emotional, cognitive and social functions compared to the placebo during chemotherapy treatment. They experienced higher cognitive function, less pain and increased appetite, and had reduced IL-17 and monocyte chemoattractant protein-1 (7). 

 

In a phase 1 clinical trial of T. versicolor in women with immune dysregulation, researchers found that up to nine grams per day of a turkey tail preparation is safe and tolerable and the women taking six grams a day had a significant trend upward in NK cell counts. (8) 

 

Pharmacy

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Double extraction. 1:1 - 1:5 liquid extract. The mushroom has been extracted with both water and alcohol.

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Hot aqueous extract. Mushroom has been boiled for multiple hours either as a tea or used as a broth.

 

Powdered extract. 1:1 - 10:1. May be extracted only with water or with both water and alcohol. The extract is then dehydrated into a powdered extract. 10:1 implies that every 1g of extract is equivalent to 10g of dried mushroom.

 

Myceliated grain. Mycelium is grown on grain substrate and when the mycelium seems to have digested the majority of the grain, the entire block is extracted.