There are more than 100,000 varieties of mushrooms on this planet, and hundreds are edible. In laboratory tests (mostly in Japan and China), a few dozen species have been confirmed to have medicinal properties. An extract from maitake mushrooms called D fraction is marketed as a dietary supplement.

Purchase Maitake Mushroom supplement
See also Agaricus extract supplement, along with Reishi extract and another mushroom extract to consider is Cordyceps supplement.

Benefit of Maitake mushroom:

Blood pressure
Antihypertensive and metabolic effects of whole Maitake mushroom powder and its fractions in two rat strains.
Mol Cell Biochem. 2002.
Maitake mushroom has been reported to favorably influence hypertension and diabetes mellitus. The purpose of this study was to compare the effects of whole Maitake mushroom powder and two extracts designated as ether soluble (ES) and water soluble (WS) on Zucker fatty rats (ZFR), a model of insulin resistance, and on spontaneously hypertensive rats (SHR), a model of genetic hypertension. In the initial study, we followed four groups of eight ZFR and SHR receiving special diets: a baseline diet (BD), BD + whole Maitake mushroom powder (20% w/w), BD + fraction ES, and BD + WS). We conclude that the examined forms of Maitake mushroom have antihypertensive and antidiabetic potential which differ among rat strains. The ES fraction may decrease SBP in SHR via alteration in the renin-angiotensin system.

Cancer
Maitake mushroom is used with chemotherapy to treat breast cancer and other cancers in Asia. Laboratory studies show that it can reduce the growth of cancer in animals. Human studies are needed before understanding the role of maitake mushroom in clinical cases of human cancer treatment.

BJU Int. 2010. Synergistic potentiation of interferon activity with maitake mushroom d-fraction on bladder cancer cells.

Nutr Cancer. 2017. Antitumoral Effects of D-Fraction from Grifola Frondosa (Maitake) Mushroom in Breast Cancer. D-Fraction is protein-bound β-1,6 and β-1,3 glucans (proteoglucan) extracted from the edible and medicinal mushroom Grifola frondosa (Maitake). The antitumoral effect of D-Fraction has long been exclusively attributed to their immunostimulatory capacity. However, in recent years increasing evidence showed that D-Fraction directly affects the viability of canine and human tumor cells, independent of the immune system. Previously, we have reported that D-Fraction modulates the expression of genes associated with cell proliferation, cell death, migration, invasion, and metastasis in MCF7 human breast cancer cells. Therefore, the purpose of the current study is to investigate if this modulation of gene expression by Maitake D-Fraction really modulates tumor progression. In the present work, we demonstrate for the first time that Maitake D-Fraction is able to act directly on mammary tumor cells, modulating different cellular processes involved in the development and progression of cancer. We demonstrate that D-Fraction decreases cell viability, increases cell adhesion, and reduces the migration and invasion of mammary tumor cells, generating a less aggressive cell behavior.

Maitake and immune system
Maitake extract is thought to benefit the immune system, and some people take this mushroom extract in order to reduce the occurrence of the common cold and the flu. Whether it is able to reduce the severity or frequency of common cold attacks is not clear.

Ann Transl Med. 2014. Immune-enhancing effects of Maitake (Grifola frondosa) and Shiitake (Lentinula edodes) extracts. The role of glucan in stimulation of immune reactions has been studied for several decades. In this report, we focused on the effects of orally administered glucan Maitake and Shiitake on immune reactions. We measured phagocytosis, NK cell activity, and secretion of IL-6, IL-12, IFN-γ as well as C-reactive protein (CRP) after 14 days of oral application of tested glucans. For comparison, active hexose correlated compound (AHCC) was used in all reactions. We found significant stimulation of defense reaction. In all cases, the most active was the Maitake-Shiitake combination, with Maitake alone being the second strongest, followed by Shiitake on its own and AHCC. Short-term oral application of natural immunomodulating glucans from Maitake and Shiitake mushrooms strongly stimulated both the cellular and humoral branch of immune reactions.

PCOS
J Alternative Complement Med. 2010. Maitake mushroom (Grifola frondosa) extract induces ovulation in patients with polycystic ovary syndrome: a possible monotherapy and a combination therapy after failure with first-line clomiphene citrate.

Pregnancy
I did a search on Medline with the keywords maitake pregnancy / pregnant and could not find any studies. Most likely small dosages would be safe, but I have no proof of this. As a general rule, unless necessary, it is best to minimize the used of herbs and medicines during pregnancy.

Studies
Cancer Immunol Immunother. 2015. Maitake mushroom extract in myelodysplastic syndromes (MDS): a phase II study. Myelodysplastic syndromes (MDS) are characterized by ineffective erythropoiesis with dysplastic bone marrow leading to peripheral cytopenia, risk of infection, and progression to acute myelogenous leukemia. Maitake mushroom beta-glucan, a dietary supplement, stimulates hematopoietic progenitor cell differentiation, granulocyte colony-stimulating factor production, and recovery of peripheral blood leukocytes after bone marrow injury. This phase II trial examined the effects of Maitake on innate immune function in MDS. Myelodysplastic syndromes patients with International Prognostic Scoring System Low- and Intermediate-1-risk disease received oral Maitake extract at 3 mg/kg twice daily for 12 weeks. Primary endpoints included neutrophil count and function tested as endogenous or stimulated neutrophil production of reactive oxygen species (ROS) by flow cytometry compared with age-matched healthy controls (HC). ROS activators were Escherichia coli, phorbol ester, and the bacterial peptide N-formylmethionyl-leucyl-phenylalanine (fMLP). Complete blood counts, chemistry panels, iron studies, and monocyte function were evaluated. Of 21 patients enrolled, 18 completed the study and were evaluable. Maitake increased endogenous (basal) neutrophil and monocyte function. Pre-treatment monocyte response to E. coli was reduced in MDS patients compared with HC and increased after treatment. fMLP-stimulated ROS production response also increased. Asymptomatic eosinophilia occurred in 4 patients. Other changes in albumin, hemoglobin, and total protein were not clinically relevant. Maitake was well tolerated. Enhanced in vitro neutrophil and monocyte function following treatment demonstrate that Maitake has beneficial immunomodulatory potential in MDS.

Maitake D Fraction enhances antitumor effects and reduces immunosuppression by mitomycin-C in tumor-bearing mice.
Nutrition. 2005.
D-Fraction, a polysaccharide extracted from maitake mushrooms (Grifola frondosa), has been reported to exhibit an antitumor effect through activation of immunocompetent cells, including macrophages and T cells, with modulation of the balance between T-helper 1 and 2 cells. We examined whether maitake D Fraction could decrease the effective dosage of the chemotherapeutic agent, mitomycin-C, necessary to control carcinoma in mice. Our results suggest that it can decrease the effective dosage in tumor-bearing mice by increasing the proliferation, differentiation, and activation of immunocompetent cells and thus provide a potential clinical benefit for patients with cancer.

Potential growth inhibitory effect of maitake D-fraction on canine cancer cells.
Vet Ther. 2004.
The postulated anticancer effect of maiteke D-fraction on three types (CF33, CF21, and CL-1) of canine and human cancer cells was evaluated. Our results show it is a potent natural agent that could be useful in treating canine cancers as well as other veterinary cancers.

Effects of D-Fraction, a polysaccharide from Grifola frondosa on tumor growth involve activation of NK cells.
Biol Pharm Bulletin. 2002.
Natural killer (NK) cells are directly cytotoxic for tumor cells and play a primary role in regulating immune responses. We monitored levels of NK cell cytotoxic activity in cancer patients receiving maitake D-Fraction extracted from maitake mushrooms (Grifola frondosa). Elevated levels of cytotoxic activity were maintained for one year. To elucidate the mechanisms underlying long-term activation of NK cells during treatment with maitake D-Fraction, we examined tumor volume and levels of IFN-gamma and TNF-alpha in MM46-bearing C3H/HeN mice to which D-Fraction was administered for 19 d. Maitake D-Fraction markedly suppressed tumor growth, corresponding with increases in TNF-alpha and IFN-gamma released from spleen cells and a significant increase in TNF-alpha expressed in NK cells. This suggests that the maitake D-Fraction activates NK cells even on the 20th day after treatment. Furthermore, D-Fraction increased macrophage-derived interleukin (IL)-12, which serves to activate NK cells. These results suggest that NK cells are not only responsible for the early effects of D-Fraction on tumor growth, but also for the long-term tumor-suppressive effects of maitake D-Fraction through increased IL-12 released from macrophages.

The effect of maitake mushrooms on liver and serum lipids.
Altern Ther Health Medicine. 1996.
Sprague-Dawley rats with hyperlipidemia were used to measure and compare the values of cholesterol, phospholipids, and triglycerides between cholesterol-fed rats and rats whose diets were fortified with 20% maitake mushroom dried powder. The values in maitake -fed rats were consistently less than those in the basic cholesterol-fed rats. The value of high-density lipoprotein cholesterol, which usually is decreased by taking high-cholesterol feed, maintained the level that it had at the beginning of the experiment. Weights of extirpated liver and epididymal fat pads were significantly less than those in the basic feed group. Our data suggest that maitake mushrooms have the ability to alter lipid metabolism by inhibiting both the accumulation of liver lipids and the elevation of serum lipids. Further studies are needed to elucidate the mechanism of activity of maitake mushrooms and to establish whether their action in humans is similar to that in the animal model tested here.

Maitake Products, Inc., a leader of research and development of Japanese Maitake mushrooms and other medicinal mushrooms, was named a corporate cancer research sponsor of the Memorial Sloan-Kettering Cancer Center in New York City. The awarding of this honor reflects the support that MPI is giving to the renowned cancer research and treatment center in its quest to improve methods for treating this deadly disease. In 1999, Memorial Sloan-Kettering inaugurated a department called Integrative Medicine Service, which is committed to providing complementary medicine treatment modalities to patients, in conjunction with conventional cancer treatments. This department is also responsible for carrying out clinical trials on promising complementary medicine treatments. One of the studies currently ongoing involves an extract of the Maitake mushroom specially made for the study. The goal of this study is to measure immune system activation in breast cancer patients and side effects, if any.

Questions
Q. Is it okay to take lipoic acid and coQ10 the same day as a maitake mushroom extraxt?
   A. I don't see why not as long as the dosage of lipoic and coq10 are kept low.

Q. Does AHCC come from maitake mushroom?
   A. To my knowledge, AHCC is derived mostly from shiitake mushroom.

Q. Can I take a maitake D-Fraction mushroom supplement the same day as serrapeptase enzyme, PawPaw Cell-Reg, or mangosteen herb?
   A. You can probably take it with mangosteen, but there is not enough known about serrapeptase to know for sure. I am not familiar with PawPaw Cell-Reg product.

Does maitake benefit anxiety?
   I don't have personal experience regarding this mushroom extract and anxiety treatment, and I have not seen studies in this regard.

I read that maitake mushroom is good for immune system and supressing cancerous tumors. they never say how many pills to take. I am sure the amount on the bottle is for general health maintenance. if you already have a cancerous tumor and are in good health otherwise, what dosage should you take? so far I am taking 9 maitake pills a day. I am going to have surgery but would like the mushrooms to be of help so want to treat it like a drug.
   Since human research with maitake mushroom extract is very limited, and since there are many different forms of cancer and many different types of maitake mushroom supplements and extracts, and each person is different in their response and severity of their cancer, no easy answers are available.

What dose of maitake mushroom extract would you give to a 45 ld. dog that recently had her spleen removed because of tumors on the spleen. She is a healthy dog and very active. She also had a basal cell tumor removed from her side earlier this year which was cancerous. We are waiting for the biopsy results on the spleen. Same with Arabinogalactans.
   The canine use or that in an animal is outside my range of knowledge.

I mix a recommended therapeutic dose of liquid Maitake Pro D-Fraction each morning with 8 ounces of water, and drink 1/3 of this mixture three times a day between meals. However I have noticed that it tastes a little different at the end of the day. Is it possible that the diluted product is deteriorating during the day from exposure to light, oxygen, etc? Should I be mixing each dose separately just before drinking it? I have not seen any information on how stable this product is over time, either in concentrated or dilute form.
    I have not, either, so I am not sure about the answer since I have no idea of how this Maitake Pro D-Fraction product is prepared by the manufacturer.

I want to tell you my story and get your opinion about why this happened to me. Here it is: I had a horrible experience with Maitake D-Fraction mushroom extract. I'll tell you the story: I was diagnosed in May 2000 with chronic lymphocytic leukemia, though in July 1998, my WBC and lymph counts were a teensy bit above normal (WBC only 10.4, lymphs 54), not enough to scare anybody, and I had a new node on the left side of my neck, a mirror image of one that I'd had on the right side of my neck for 10 years, that my internist freaked me out about because he said "feels like a tumor you should have a biopsy." I had tiny neck nodes for years. I was very scared. I remembered the warning signs of cancer, and one is a lump. I spent the next 2 years ignoring an obvious problem and trying desperate measures such as hot castor oil packs to my neck and various herbal tinctures and other stuff to get rid of the tumor on my own. In my effort to get rid of it and a couple more I had, when I still had only a few total, in Dec. 1999 (remember the timeline), while suffering with a garden variety cold, I took Maitake d-Fraction mushroom extract, the extra-strength at $90 a bottle (it was liquid drops you took), and I took like a double dose, I got the shock of my life. First of all, I was taking the Maitake because of allt he good things I read about it stimulating the immune system. I thought (hello!) that that was just what I needed to get rid of the enlarged nodes (obviously this was before I knew anything at all about CLL). Well, here's the shocker: one morning after I had done the double dose mushroom crap, I awoke to a veritable mushroom crop of enlarged nodes around my neck, there were 6 or 7 that I didn't previously have, several were downright huge. Turns out, I theorized much, much later, that the mushroom was a bit TOO stimulating to my immune system, and aggravated by the cold virus, may have triggered the CLL to reproduce wildly. The next spring (long story) I found out I had CLL. I came to the conclusion that, at least for immune system cancers, and at least for me, the mushrooms cause cell proliferation. What do you think? And what do you think about some fringy type people saying that all cancers are caused by fungi? I don't think the mushroom extract caused my chronic lymphocytic leukemia, but i think that it may have accelerated it.
    Cancer has a variety of causes, not just one. I am not sure what percent of cancers are influenced by a fungal infection, but it is likely to be quite low. Thanks for sharing your experience with us.

Other products
Maitake Beta-Factor supplement, Planetary Formulas
Dr. Nanba's Maitake Beta-Factor by Planetary Formulas contains Dr. Nanba's unique MaitakeGold 404 beta-glucan fraction, the fully mature fruiting body and the mycellium. This provides a complete spectrum of activity.
Lifestyle Recommendations: To support immune defenses, get enough rest, drink plenty of pure water, exercise regularly, avoid excessive stress and supplement the diet with antioxidant nutrients.
Consists of MaitakeGold 404 which is a trademark of The Tradeworks Group, Inc. U.S. Patent number 5,854,404.
Supplement Facts:
Vitamin C (as ascorbic acid)
Calcium
Maitake ( beta-glucan ) Fraction
Blend: Maitake Fruiting Body and Myceila Biomass

Maitake Mushroom 15%, 20% Polysaccharides -- sx fraction

Grifron Maitake, Mushroom Wisdom, Maitake D-Fraction Pro 4X, 120 Veggie Tabs

Buy Maitake mushroom d-fraction veggie tabs