Shiitake by Herbal Terra

POSSIBLY INEFFECTIVE

• Dental Plaque. A solution containing an extract of shiitake mushroom is less effective than fluoride mouthwash for reducing dental plaque. Details: Clinical research shows that rinsing the mouth with a solution containing shiitake mushroom extract does not reduce dental plaque when compared with placebo and appears to be less effective than fluoride mouth rinse (Meridol) (94250).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Aging. Although there has been interest in using oral shiitake mushroom for aging, there is insufficient reliable information about the clinical effects of shiitake mushroom for this purpose.
• Atherosclerosis. Although there has been interest in using oral shiitake mushroom for atherosclerosis, there is insufficient reliable information about the clinical effects of shiitake mushroom for this purpose.
• Breast cancer. Although there has been interest in using oral shiitake mushroom for breast cancer, there is insufficient reliable information about the clinical effects of shiitake mushroom for this purpose.
• Cancer. It is unclear if oral shiitake mushroom is beneficial in patients with cancer. Details: Although some small clinical studies in patients with gastric or colon cancer have found that patients taking the shiitake mushroom extract AHCC 3-6 grams daily have better survival rates and quality of life when compared with historical population data, other observational research has not found a benefit for patients with head, neck, lung, or breast cancer when compared with baseline (30421,30425,30454). The validity of these studies is limited by lack of a comparator group.
• Chemotherapy-induced anemia. It is unclear if oral shiitake mushroom is beneficial in patients with chemotherapy-induced anemia. Details: A small clinical study in adults receiving chemotherapy for pancreatic cancer shows that taking the shiitake mushroom extract AHCC 6 grams daily for 8-12 weeks does not reduce the rate of grade 2 to 3 anemia when compared with placebo (110131).
• Chemotherapy-induced leukopenia. It is unclear if oral shiitake mushroom is beneficial in patients with chemotherapy-induced leukopenia. Details: Preliminary clinical research in patients with breast cancer receiving chemotherapy shows that taking the shiitake mushroom extract AHCC significantly reduces chemotherapy-related neutrophil events and lipid abnormalities when compared with standard care (94829).Observational research in patients with resectable pancreatic ductal adenocarcinoma has found that taking this product orally 3 grams daily throughout 2 cycles of neoadjuvant gemcitabine improves the neutrophil-to-lymphocyte ratio and nutritional scores when compared with standard of care (106783). In contrast, other clinical research in patients with pancreatic or biliary tract cancer receiving gemcitabine chemotherapy shows that taking AHCC 6 grams daily for two months does not seem to affect neutropenia, thrombocytopenia, or hepatic dysfunction when compared with standard of care. However, taking AHCC did reduce C-reactive protein and increase hemoglobin and albumin when compared to standard of care (30424).
• Chemotherapy-induced nausea and vomiting (CINV). It is unclear if oral shiitake mushroom is beneficial in patients with CINV. Details: Preliminary clinical research in patients being treated for head and neck cancers shows that taking the shiitake mushroom extract AHCC 3 grams daily, beginning 3 days prior to chemotherapy and continuing until one week after chemotherapy, reduces gastric side effects and the need for antiemetic therapy when compared with baseline (30425). The validity of these findings is limited by the lack of a comparator group.
• Chemotherapy-induced taste changes. It is unclear if oral shiitake mushroom is beneficial for the prevention of taste changes due to chemotherapy. Details: A small clinical study in adults receiving chemotherapy for pancreatic cancer shows that taking the shiitake mushroom extract AHCC 6 grams daily for 8-12 weeks reduces the rate of patient-reported taste disorders by 27% when compared with placebo (110131). Although patients in the AHCC group had modest improvements in some nutritional parameters when compared with the placebo group, it is unclear if any changes would be considered clinically significant.
• Common cold. Although there has been interest in using oral shiitake mushroom for the common cold, there is insufficient reliable information about the clinical effects of shiitake mushroom for this purpose.
• Coronavirus disease 2019 (COVID-19). Although there has been interest in using oral shiitake mushroom for COVID-19, there is insufficient reliable information about the clinical effects of shiitake mushroom for this purpose.
• Diabetes. Although there has been interest in using oral shiitake mushroom for diabetes, there is insufficient reliable information about the clinical effects of shiitake mushroom for this purpose.
• Genital herpes. Although there has been interest in using oral shiitake mushroom for genital herpes, there is insufficient reliable information about the clinical effects of shiitake mushroom for this purpose.
• Hepatitis C. It is unclear if oral shiitake mushroom is beneficial in patients with hepatitis C. Details: Preliminary clinical research in adults with chronic hepatitis C shows that taking the shiitake mushroom extract AHCC 6 grams daily for 6 months does not significantly reduce alanine aminotransferase (ALT) or hepatitis C virus RNA levels when compared with placebo (30419).
• HIV/AIDS. Although there has been interest in using oral shiitake mushroom for HIV/AIDS, there is insufficient reliable information about the clinical effects of shiitake mushroom for this purpose.
• Human papillomavirus (HPV). It is unclear if oral shiitake mushroom is beneficial in patients with HPV. Details: A small clinical study in adult females with persistent high-risk HPV shows that taking the shiitake mushroom extract AHCC 3 grams daily leads to clearance of HPV RNA and DNA in 64% of patients after 6 months of treatment, compared to 11% of patients taking placebo (110129). The validity of these findings is limited by lack of statistical comparison between groups.
• Hypercholesterolemia. It is unclear whether oral shiitake mushroom is beneficial for lowering blood lipid levels. Details: Clinical research in adults with borderline high levels of cholesterol or triglycerides shows that consuming bars providing shiitake mushroom for 66 days modestly reduces triglyceride levels, but does not affect levels of low-density lipoprotein (LDL) cholesterol or high-density lipoprotein (HDL) cholesterol, when compared with placebo bars. Each bar provided dried shiitake mushroom 3.5 grams daily and the number of bars consumed daily was based on body mass index (108300). The effect of shiitake mushroom in patients with hypercholesterolemia, specifically, is unclear due to the heterogenous patient population.
• Hypertension. Although there has been interest in using oral shiitake mushroom for hypertension, there is insufficient reliable information about the clinical effects of shiitake mushroom for this purpose.
• Impaired glucose tolerance (prediabetes). Oral shiitake mushroom has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in adults with prediabetes shows that taking freeze-dried shiitake mushroom 0.96 grams in combination with chokeberry 1.36 grams, Panax ginseng 1.64 grams, and nattokinase 0.8 grams (Chakreis, YD Nutraceuticals Ltd.) twice daily for 12 weeks does not affect glycated hemoglobin, fasting blood glucose, or oral glucose tolerance test results when compared with placebo. However, there were some modest beneficial effects on insulin resistance and fasting insulin and liver transaminase levels (108301).
• Influenza. Although there has been interest in using oral shiitake mushroom for influenza, there is insufficient reliable information about the clinical effects of shiitake mushroom for this purpose.
• Liver cancer. Small, low-quality clinical studies suggest that oral shiitake mushroom extract may improve overall survival in patients with liver cancer. Details: Preliminary clinical research in patients with advanced hepatic cancer shows that taking the shiitake mushroom extract AHCC orally 6 grams daily for a median of 3.5 months along with supportive care increases the median survival time by 2 months when compared with placebo. Taking AHCC also improved quality of life scores when compared with placebo (30359). Population research in patients with hepatocellular carcinoma has also found that taking AHCC 3 grams daily for up to 9 years after surgical resection reduces tumor recurrence and mortality by 48% and 56%, respectively, when compared with control (30353). In another small, open label clinical study of adults with advanced hepatocellular carcinoma, tumor recurrence occurred in 52% of patients who took AHCC 1 gram three times daily for 2 years after surgical resection (110130). The interpretation of these results is limited by the lack of a control group.
• Obesity. Although there has been interest in using oral shiitake mushroom for obesity, there is insufficient reliable information about the clinical effects of shiitake mushroom for this purpose.
• Prostate cancer. It is unclear whether shiitake mushroom has a role in preventing disease progression. Details: Preliminary clinical research shows that taking shiitake mushroom extract does not prevent disease progression, as determined by prostate-specific antigen (PSA) levels, when compared with baseline (10451). More evidence is needed to rate shiitake mushroom for these uses.

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LIKELY SAFE ...when consumed in typical food amounts (6).

POSSIBLY SAFE .... ..when the shiitake mushroom extract AHCC is used orally and appropriately. AHCC 4.5-6 grams daily has been used with apparent safety in clinical trials lasting up to 6 months (22926,30419). Population research identified no safety concerns with the use of AHCC 3 grams daily for up to 9 years (30353,94830).

POSSIBLY UNSAFE ...when shiitake mushroom powder is used orally in medicinal amounts. Ingestion of shiitake mushroom powder 4 grams daily for 10 weeks can cause eosinophilia (1149). ...when uncooked shiitake mushroom is ingested. The lentinan component, which is broken down by heat, can cause toxic reactions, including shiitake dermatitis (94354).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid consuming greater than food amounts.

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CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, shiitake mushroom might decrease levels of drugs metabolized by CYP2D6.  Details In vitro studies suggest that the shiitake mushroom extract AHCC might induce the CYP2D6 enzyme (30369,30420). This effect has not been reported in humans.

IMMUNOSUPPRESSANTS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking shiitake mushroom might decrease the effects of immunosuppressive therapy.  Details In vitro evidence suggests that shiitake mushroom extracts stimulate immune function (30351,30358,30360,30361,30366,30367,30368,30371,30376,30379,30381,30382,30416,30418) (74769,74783,74876,94245).

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General ...Orally, shiitake mushroom is generally well tolerated when cooked and consumed as a food.
Most Common Adverse Effects:
Orally: Abdominal discomfort, bloating, diarrhea, nausea, and vomiting.
Serious Adverse Effects (Rare):
Orally: Consumption of raw shiitake mushroom can cause shiitake dermatitis, a skin eruption resembling whiplash marks which can be accompanied by systemic symptoms. Large pieces that have been inadequately chewed can cause intestinal blockage, occasionally requiring surgery.

Dermatologic ...Orally, shiitake mushrooms can cause shiitake dermatitis, a skin eruption that resembles whiplash marks, usually found on the trunk and limbs. This dermatitis is thought to be a toxic response to lentinan or other compounds found normally in uncooked or inadequately cooked shiitake mushroom. The rash can be made worse by scratching. Symptom onset is usually within hours to days and can persist for 3-4 weeks before resolving on its own. There is some evidence that treatment with steroids alone or with antihistamines might reduce the duration of the rash by a small amount in some people (1148,1152,74782,74806,94236,94237,94238,94240,94241,94243) (94244,94246,94247,94248,94249,94252,94253,94254,94255,94256)(94257,94259,94261,94262,108302,111909,111912,111913). The dermatitis may include small purple spots from broken capillaries, skin plaques, burning, blanching, and pustules (94256,108302). Rarely the rash may look like measles rather than whiplash (94256). Histologically, there may be evidence of dermal and epidermal edema, lymphocyte infiltration, and skin thickening (94256,94257). Other symptoms associated with the dermatitis include fever, aching, malaise, eosinophilia, diarrhea, prickling in the hands, trouble swallowing, conjunctivitis, and pustules with small ulcers in the mouth (94240,94246,94247,94249,94256,94257,108302). It is likely that the dermatitis and other symptoms are due to a delayed type hypersensitivity reaction (94244,94255). Cooking shiitake mushroom generally prevents shiitake dermatitis, although some cases have occurred in people who have consumed cooked sources (94242,94244). It appears that to inactivate lentinan, cooking temperatures of at least 130°C are needed (94243).
Less common is a photosensitivity reaction associated with oral ingestion, which involves rash and pruritus after sun exposure (1148,94241).
Orally, the shiitake mushroom extract AHCC has been reported to cause mild itching (30375).

Gastrointestinal ...Orally, shiitake mushrooms can cause abdominal discomfort, including bloating, nausea, pain, vomiting, and diarrhea (1149,30365,30375,30419,94241). Gastrointestinal symptoms, such as diarrhea, problems swallowing, or mouth ulcers have been associated with shiitake dermatitis (94241,94256). Consumption of large pieces of shiitake mushroom with inadequate chewing can cause abdominal obstruction that has resulted in death in one case and surgical intervention in two others. In another case, parenteral nutrition was used exclusively until the shiitake mushroom pieces were passed (1147,94260,103160,108303,108304).
Topically, an oral rinse containing shiitake mushroom extract has been associated with teeth sensitivity, teeth staining, and burning in the mouth (94250).

Hematologic ...Ingestion of shiitake mushroom powder 4 grams daily for 10 weeks caused eosinophilia in 5 of 10 healthy humans (1149). Eosinophilia, and leukocytosis or leukopenia have been reported with shiitake dermatitis (94254,94256,94257).

Immunologic ...Allergic contact dermatitis can occur by contact with shiitake hyphae (filaments) (1153,74785,111913). It appears to be more common in growers or others that handle shiitake mushrooms extensively (94241,94259). Contact or inhalation also results in other symptoms of allergy, such as asthma, rhinitis, conjunctivitis, and pneumonia (94241,94249,94258,94259).

Musculoskeletal ...Orally, the shiitake mushroom extract AHCC has been reported to cause foot cramps and difficulty moving hand joints (30365,30416).

Neurologic/CNS ...In patients experiencing shiitake dermatitis, other symptoms may include prickling in the hands (94256). Malaise has also been reported following oral intake or contact (1151,94240).
Orally, the shiitake mushroom extract AHCC has been reported to cause mild and transient headache (30365).

Ocular/Otic ...Conjunctivitis has been reported rarely in mushroom growers and handlers, or following oral intake in patients with shiitake dermatitis (94241,94256,94259).

Pulmonary/Respiratory ...In mushroom workers, hypersensitivity pneumonitis due to shiitake spore inhalation has occurred. Symptoms include difficulty breathing, chest pain, a dry cough, asthma, and rhinitis (1150,1151,74776,74813,94239,94241,94258,94259).

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