Shiitake mushrooms are a dietary staple in Asia and are increasingly popular worldwide. There are several mushrooms available for sale including Maitake mushroom and Reishi mushroom. If you have an interest in learning about the health benefits of mushrooms and mushroom extracts, including their medicinal value, consider signing up to a free email Newsletter.

AHCC and Shiitake
AHCC is an extract of mycelium, obtained through the long-term cultivation of several types of basidiomycetes medicinal mushrooms including Shiitake.

Shiitake Mushroom Side Effects
One report suggests allergy potential if shiitake mushroom is ingested regularly.

Shiitake Clinical Research Update
Effects of a mushroom mycelium extract on the treatment of prostate cancer.
Urology. 2002 Oct;60(4):640-4. deVere White RW, Hackman RM, Soares SE, Beckett LA, Sun B.
Department of Urology, University of California, Davis, School of Medicine, Sacramento, California 95817
To determine whether supplemental amounts of a polysaccharide/oligosaccharide complex obtained from a shiitake mushroom extract would lower the prostate-specific antigen (PSA) level in patients with prostate cancer. METHODS: A total of 62 men (mean age 73.2 years, range 53.6 to 85.5) with histologically proven prostate cancer who had two consecutive elevated PSA readings were accrued to the study during a 3-month period. This was an open-label study in which the patients received oral administration of capsules containing shiitake mushroom extract given three times daily for 6 months. The endpoint for the trial was the lowering of the PSA levels. RESULTS: Of the 62 men enrolled in the study, 61 were assessable. At 4 months, 1 patient withdrew because of unrelated surgery and 7 withdrew because of disease progression; none had responded with a decrease of greater than 50% in the PSA level. By 6 months, a total of 23 patients had progression and none had responded. Thirty-eight patients had stable PSA levels after 6 months. Although not the primary endpoint of the study, in other studies these patients could have been included as responders. When the patients' rates of PSA rise before study entry were analyzed, 4 (7%) had stabilized disease while taking shiitake mushroom extract. Thus, the final results for our study patients were 0 with a complete response, 0 with a partial response, 4 (7%) with stable disease, and 23 of 61 with progression while taking shiitake mushroom extract. CONCLUSIONS: shiitake mushroom extract alone is ineffective in the treatment of clinical prostate cancer.

A placebo-controlled trial of the immune modulator, lentinan, in HIV-positive patients: a phase I/II trial.
J Med. 1998;29(5-6):305-30. Gordon M, Bihari B, Goosby E, Gorter R, Greco M, Guralnik M, Mimura T, Rudinicki V, Wong R, Kaneko Y.
AIDS Activities Division, San Francisco General Hospital, CA
Lentinan is a beta 1-->3 glucan isolated from Lentinus edodes ( Shiitake mushroom ) which has immune modulating properties. We have conducted two phase I/II placebo-controlled trials on a total of 98 patients. In one study at the San Francisco General Hospital (SFGH), ten patients each were administered 2, 5, or 10 mg of lentinan or placebo i.v. once a week for eight weeks. In the second study at the Community Research Initiative in New York (CRI), two groups of 20 patients each were administered 1 or 5 mg of lentinan i.v. twice a week for 12 weeks, and ten patients were administered placebo (vehicle containing mannitol plus dextran 40) i.v. twice a week. Entry criteria were an HIV positive test, CD4 levels of 200-500 cells, age 18-60 years, and without current opportunistic infections. This study confirms, in Caucasian subjects also, the good tolerability of lentinan observed in Japanese cancer patients. Side effects were mainly mild, especially when infusion was carried out over a 30-minute period. In the SFGH study, where administration was over a ten minute period, there were nine side effects severe enough to be reported to the FDA (one case each of anaphylactoid reaction, back pain, leg pain, depression, rigor, fever, chills, granulocytopenia and elevated liver enzymes) and there were four patients who discontinued therapy because of side effects. In the CRI study, where infusion was over a 30-minute period, there were no side effects reportable to the FDA and there were four dropouts due to side effects or personal preference. Most side effects resolved promptly after the discontinuation of medication, and all of them were relieved within 24 hours. Patients in the study have shown a trend toward increases in CD4 cells and in some patients neutrophil activity. Because of the small numbers, these values do not have statistical significance. Inasmuch as no side effects such as anemia, leukopenia, pancreatitis or neuropathy were seen, and in view of the positive effects of lentinan on certain surrogate markers (recognizing that these were small studies), we recommended a long-term clinical trial of lentinan in combination with didanosine (ddI) or zidovudine in HIV positive patients. Most patients in these trials did not have measurable p24 levels. In the CRI trials of ten patients with elevated p24 levels, eight on lentinan and two on placebo had decreased p24 levels. Of these decreases, those with lentinan and one with placebo were marked. These results were provocative and needed confirmation. Subsequent to this study, a trial of lentinan in combination with didanosine (ddI) showed a mean increase of 142 CD4 cells/mm3 over a twelve month period, in contrast to a decrease in CD4 cells in patients on ddI alone (Gordon et al. 1995).

Eosinophilia and gastrointestinal symptoms after ingestion of shiitake mushrooms.
J Allergy Clin Immunol. 1998 May;101(5):613-20.
A cholesterol-lowering study with shiitake showed that 17 of 49 participants withdrew because of rash or abdominal discomfort, and two had marked eosinophilia. One of these latter participants was subsequently challenged for 14 days with shiitake powder and again had eosinophilia. OBJECTIVE: We investigated whether ingestion of shiitake mushroom powder induces eosinophilia or symptoms. METHODS: We studied 10 normal persons. Each participant ingested 4 gm shiitake powder (open label) daily for 10 weeks (trial 1), and the protocol was repeated in these same subjects after 3 to 6 months (trial 2). Blood counts and serum samples were obtained biweekly (trial 1) or weekly along with stool specimens (trial 2). Eosinophil major basic protein and IL-5, IgE, and IgG antishiitake antibodies were measured in sera. Eosinophil-derived neurotoxin was measured in stool extracts. We defined responders as subjects having peak eosinophil counts four or more times their average baseline counts. RESULTS: Each trial had four responders, and trial 2 had one new and three repeat responders. Eosinophilia ranged from 400 to 3900/mm3. Responders had increased blood eosinophils, serum major basic protein, stool eosinophil-derived neurotoxin, and factors that enhanced eosinophil viability. Antishiitake IgE was not detected, and antishiitake IgG increased in two responders. Gastrointestinal symptoms coincided with eosinophilia in two subjects. Symptoms and eosinophilia resolved after discontinuing shiitake ingestion. CONCLUSIONS: Daily ingestion of shiitake mushroom powder in five of 10 healthy persons provoked blood eosinophilia, increased eosinophil granule proteins in serum and stool, and increased gastrointestinal symptoms. Shiitake ingestion suggests a model to study the eosinophil's role in the blood and gastrointestinal tract. Finally, our report raises concerns of possible adverse systemic reactions to this increasingly popular food.

some people misspell shiitake as shitake