Coriolus versicolor is hardly exotic. In fact, it may be one of the most ubiquitous tree-dwelling mushrooms in the world, found in temperate woodlands throughout the US, Europe, and Asia.
A member of the Polyporaceae family, it is known colloquially as the Turkey Tail. The Chinese call it Yun Zhi ("cloud mushroom"), while the Japanese call it Kawaratake ("riverbank mushroom"). Though this fungus does not appear in European or Native American herbal traditions, it is highly valued by Chinese herbalists, who consider it a "warming" mushroom, used to dispel dampness, reduce phlegm, and increase vigor in fighting infections.
Where Tradition and Biochemistry Meet
Modern biochemical medicine and ancient traditional practices are not always in accord. But when it comes to preparation of medicinal mushrooms, particularly the woody types like Coriolus and Reishi, it seems that tradition and pharmacology agree on one thing: hot water is necessary to properly prepare these myco-medicines.
Chinese tradition advises boiling these mushrooms as teas, and it appears that hot water extraction remains the best way to obtain the beneficial polysaccharides. Chitin is the primary building block of the mushroom structure, and many of the immunologically-active mushroom compounds are contained within the chitinous cell walls. Hot water can break down the chitin, freeing the polysaccharides.
Later, certain fractions can be further extracted with ethanol. But ethanol extraction without heat, as a first step, is suboptimal. Cold alcohol extraction (tincture) is excellent for cellulose-based materials, but generally does not break down chitin.
Mushroom polysaccharides come out of solution at 30% alcohol, and a good way to know if an alcohol-containing product contains active polysaccharides is to look for sediment at the bottom of the bottle.
Though there are a number of Coriolus products on the market made from ground mushroom mycelium, it is unclear whether the body can break down the chitinous material enough to make the key polysaccharides bioavailable. Nearly all of the studies showing therapeutic effects with this mushroom have been on water or water and alcohol extracts.
The Japanese have pioneered the pharmacologic use of C. versicolor. Since the mid-1970's, polysaccharides extracted from its cell walls have been approved by the Japanese Health and Welfare Department as a drug for treating lung, colon, breast and stomach cancers. The Coriolus proteoglycan, polysaccharide-K (PSK), is used widely in Japan, available by prescription only, and covered by the national health plan.
"This is standard therapy in Japan," said John Seleen, president of JHS Natural Products, which markets VPS Coriolus versicolor extract, a hot-water extract almost identical to the Japanese PSK product, as well as the PSP polysaccharide extract, widely used as an OTC drug in China. Coriolus polysaccharides are, "definitely not a cure (for cancer), but they can give moderate to strong improvement in outcomes."
Published trials show that depending on the type of cancer, PSK or PSP taken orally, can increase 5-year survival rates by 2-3 fold. Coriolus extract has been tested with and without chemotherapy or radiation, and in both contexts it can improve survival.
Polysaccharide K (PSK)
In a randomized study of 262 patients undergoing surgical resection of gastric cancers at the Yokoyama GI Hospital, Japan, addition of PSK, 3 g per day, to adjuvant mitomycin or fluorouracil chemotherapy improved 5-year disease-free rates and 5-year survival rates. Of subjects receiving the mushroom extract, 71% were disease-free at 5 years, compared with 59% of those on standard chemotherapy alone. The 5-year survival rate was 73% for the PSK-treated group versus 60% for those on standard treatment alone (Nakazato H, et al. Lancet 1994; 343: 1122–1126).
That trial builds on an earlier multicenter randomized study of 111 post-operative colorectal cancer patients followed for up to 8 years, that showed significantly higher disease-free rates and survival rates among those on PSK versus those on placebo. No other adjuvant or maintenance treatments were given. These patients were given 3 g PSK daily for the first two post-op months. The dose was then stepped-down to 2 g daily until post-op month 24, and then stepped-down to 1 g thereafter (Torisu M et al. Cancer Immunol Immunother, 1990; 31: 261–268).
Motomichi Torisu, MD, author of the colorectal cancer study, proposed that "PSK … is absorbed in the intestine, and enters general circulation where it activates the complement system to generate C5a, which in turn, activates leukocytes … (which) attack resurgent cancer cells … inducing a delay in recurrence of the disease."
PSK improved 5-year survival when given as an adjuvant to radiotherapy in 185 patients with non-small cell lung cancer. The treated patients, with stage I or II disease, had a 39% 5-year survival rate compared to 22% in those not receiving the mushroom extract. For patients with stage III disease, the difference was 16% versus 5% (Hayakawa K, et al. Anticancer Research 1993; 113: 1815–1820).
To varying degrees, PSK has shown anti-tumor effects and survival benefit as adjuvant therapy against acute leukemia (Nagao T, et al. Tokai J Exp Clin Med 1981; 6: 141–146). At a recent conference on Asian Therapies for Cancer, Joseph Wu, MD, of the Brander Cancer Research Institute, New York Medical College, said that reformulated C. versicolor polypeptides produced a dose and time-dependent growth suppression of promyelocytic leukemia cell cultures.
PSK was shown to improve post-operative survival in breast cancer (Iino Y, et al. Anticancer Research 1995; 15: 2907–2912), and there is preclinical work suggesting that PSK has promise in treating prostate cancer. The mushroom extract markedly increased tumor doubling times and host survival times in immunodeficient mice carrying human metastatic prostate adenocarcinoma (Mickey D, et al. Int J Immunopharmacol 1989; 11(7): 829–838).
Investigators at New York Medical College tested a 70% ethanolic extract of Coriolus in 3 hormone-refractory and one androgen-sensitive prostate cancer cell lines. The mushroom extract significantly reduced cell growth and PSA secretion in the androgen-sensitive line, but had little effect in the androgen-refractory lines (Hsieh TC, et al. Int J Oncol 2001; 18(1): 81–88).
PSP is a protein-bound polysaccharide from Coriolus that enhances cell-mediated immunity. It is structurally similar to PSK, except that PSK contains fucose, while PSP contains arabinose and rhamnose.
Preclinical experiments with rats showed that PSP at an oral dose equivalent to 2 g per kg per day, was able to reverse cyclophosphamide-induced immunosuppression. The treated animals showed increased lymphocyte proliferation, increased natural killer cell function, and increased production of white blood cells, all of which were previously suppressed by cyclophosphamide. The PSP-treated rats also showed increased IgG and IL-2 production (Qian ZM, et al. Am J Chin Med 1997; 25(1): 27–35).
In China, PSP has been tested as adjunctive therapy for esophageal, stomach and lung cancer. The first of these trials began in 1992. A total of 485 patients (172 with esophageal carcinoma; 162 with stomach cancer; and 151 with squamous cell or adenocarcinoma of the lung) were enrolled; 346 of them were given PSP, 0.34 g, thrice daily, in conjunction with two courses of standard radiation or chemotherapy, depending on the type of cancer. PSP was continued for two months. Controls were given batilol, 50 mg, thrice daily.
Investigators were particularly interested in immune function and quality of life, which they assessed using the Karnofsky performance standard, and by measuring natural killer cell function, IL-2 production, and white blood cell counts. The PSP was considered "effective" if clinical symptoms improved and the immunological indices remained stable or improved by one-third or more.
PSP increased natural killer cell activity by 65–69%. Among the stomach cancer patients, 80% of those on PSP had improved Karnofsky scores and symptom profiles, as compared to only 32% of the batilol controls. The investigators observed a similar though slightly smaller effect in the lung cancer subjects. Among those with esophageal cancers, 97% of the PSP group had symptom improvments, compared with 77% of the controls. This trial was not designed to assess survival.
A second study involved 650 people with stomach, esophageal or lung cancers at 14 Chinese hospitals between 1996 and 1997. All were treated by conventional methods appropriate to their tumor types, along with PSP, one gram thrice daily, or batilol, 150 mg, daily for two months. For all three cancer types, those on PSP had far better quality-of-life scores. Over 40% of those on the mushroom had increases in appetite and weight gains of 1 kg or more, versus only 15% in the control group. These studies were funded by the Shanghai Public Health Bureau and the Chinese Ministry of Public Health, and have not yet been published in an English language journal.
THE REDUX: Coriolus versicolor, a woody tree-dwelling mushroom, has been used for centuries in Asia as an immune system strengthener. This fungus contains several polysaccharides shown in preclinical experiments to upregulate cell-mediated immunity and inhibit tumor cell growth. In Japan and China, two such polysaccharides, PSK and PSP, are widely used as prescription medicines for treatment of lung, GI, and breast cancer. While not "cures," the published trials show prolonged survival and disease-free periods when the extracts are used as adjuncts. Heat is essential to break down the chitin cell walls of this mushroom to obtain the polysaccharides; hot water extraction is the optimal method, as was recognized by Chinese physicians hundreds of years ago.