Maitake: The Medicinal Mushroom for Immunity and Blood Sugar, What the Research Says

In the world of medicinal mushrooms, there are several stars that appear again and again: Reishi, Cordyceps, Turkey Tail, and alongside them Maitake (Grifola frondosa), a large Japanese mushroom that grows in curled clusters at the base of trees, whose traditional nickname is the "dancing mushroom". According to legend, whoever found it in the forest danced with joy, perhaps because of its sought-after taste or perhaps because of its attributed medicinal value in East Asian tradition.

In recent decades, maitake has moved from the kitchen to the supplement shelf, and is marketed today as an immune supporter, blood sugar balancer, and even an aid for fertility. Its main active components are beta-glucans, complex sugars that have been given commercial names like D-fraction, MD-fraction, and SX-fraction. But as always in this field, one must separate the marketing promise from what science has actually shown. The evidence in the lab and in animals is intriguing, but the evidence in humans is still scarce and small. In this article, we will make this distinction and explain why we rated maitake yellow.

What is Maitake?

Maitake is an edible mushroom from the genus Grifola, originating mainly in Japan, China, and North America. Here is what is important to understand about it:

• It is rich in beta-glucans. These are complex sugars (polysaccharides) found in the cell wall of mushrooms, and they are considered the main active component behind the immune effects attributed to it.
• It has named commercial "fractions." Japanese researchers isolated defined fractions from it: D-fraction and MD-fraction were studied mainly for immune effects, and SX-fraction (a water-soluble glycoprotein) was studied for balancing blood sugar and insulin.
• It is a food with nutritional value. As an edible mushroom, it provides fiber, B vitamins, vitamin D (when exposed to light), and minerals, similar to other mushrooms.
• It is sold in several forms. It can be found as a fresh mushroom for cooking, as a powder, as a concentrated liquid extract, or as capsules of a standardized beta-glucan extract.

It is important to emphasize a point that recurs with all medicinal mushrooms: Not all maitake supplements are the same. The difference between raw mushroom powder and a standardized extract containing a known percentage of beta-glucan is enormous, and it directly affects the potential effectiveness. Most of the studies we have were done with specific, standardized fractions, not necessarily with the cheap powder on the shelf.

The Connection to Immunity and Blood Sugar: The Mechanism

Maitake is attributed with two main directions of activity, each with a proposed separate mechanism. The first direction is immune regulation, and the second direction is metabolic balancing of blood sugar and insulin.

First mechanism, beta-glucan and the immune system. Beta-glucans are not foreign molecules to our body: we have dedicated receptors for their recognition on the surface of immune cells, such as the Dectin-1 receptor and CR3 receptors. When beta-glucan from the mushroom binds to these receptors, it may "awaken" and coordinate innate immune cells like macrophages and NK cells. In laboratory and animal studies, the D-fraction of maitake showed an effect on balancing Th1 versus Th2 helper T cells and on the production of inflammatory mediators like interferon gamma and interleukin 12. This is the scientific reason for the interest in the mushroom as an immune supporter.

Second mechanism, SX-fraction and insulin sensitivity. Here the story is different. The SX-fraction, a water-soluble glycoprotein, was studied mainly for its ability to improve insulin sensitivity. The proposed explanation is that it affects the insulin signaling pathway inside muscle cells, from the receptor to the Akt protein, and thus increases the uptake of sugar from the blood into the cells. Additionally, certain components in the mushroom may inhibit the enzyme alpha-glucosidase in the intestine, which breaks down complex carbohydrates into simple sugars, and thus slightly slow the rise in blood sugar after a meal.

It is important to note the opposite direction of the two mechanisms in terms of caution. The same immune effect that might help is exactly what requires caution in people with autoimmune diseases. And the same blood sugar-lowering effect that might help is exactly what could cause excessive drops in blood sugar in someone already taking diabetes medications. We will return to this later.

The Current Evidence

Study 1: Maitake and Immune Function, Phase 1/2 Trial by Deng et al. 2009

This is one of the most important clinical studies on maitake in humans, and it precisely illustrates how complex the picture is. In 2009, Deng and colleagues from the Memorial Sloan-Kettering Cancer Center published a phase 1/2 trial in the journal Journal of Cancer Research and Clinical Oncology that included 34 postmenopausal women who had breast cancer.

The women took an oral maitake polysaccharide extract, at escalating doses of 0.1 to 5 mg per kg of body weight, twice daily, for 3 weeks. The researchers found a statistically significant association between maitake and changes in immune function, but the surprising finding was that the effect was not unidirectional: different doses increased some immune parameters and suppressed others, and the dose-response curves were not linear. The researchers' fair conclusion was that maitake affects the immune system in a more complex way than assumed, and may both suppress and enhance immune function. This is an important reminder: "immune boosting" is not a simple concept, and more is not always better.

Study 2: Maitake and Fertility in PCOS, Trial by Chen et al. 2010

Another intriguing research area relates to Polycystic Ovary Syndrome (PCOS), where insulin resistance is a key feature. In 2010, Chen and colleagues published a trial in Japan in the journal Journal of Alternative and Complementary Medicine that included about 80 patients with PCOS, examining the SX fraction of maitake as an ovulation inducer.

Some women received maitake extract (MSX), and some received clomiphene citrate, the standard drug for inducing ovulation. The results suggested that maitake alone might induce ovulation in some patients, and that it might also help as an adjunctive treatment in women who did not respond to first-line therapy. The rationale aligns with the mechanism: improving insulin sensitivity is a known way to affect ovulation in PCOS. However, this is a single, relatively small study, and larger, randomized, more independent trials are needed before maitake can be recommended as an established fertility treatment. It is a promising sign, not proof.

Study 3: Maitake, Blood Sugar, and Blood Pressure, Animal Studies

A significant portion of the evidence on maitake's effect on blood sugar still comes from animals. A study published in the journal Journal of Medicinal Food examined the SX fraction in diabetic rats and found that it lowered blood sugar levels, improved insulin sensitivity, and also lowered systolic blood pressure.

These findings explain the interest in the mushroom as a metabolic supporter, but it is important to remember the fundamental limitation: what works in a diabetic rat does not necessarily work with the same potency, or at all, in a human. An effect on blood pressure was also observed mainly in animal models. Until large human trials tracking HbA1c and blood pressure measures over time are available, this direction should be considered preliminary and promising, not established.

What About General Health and Longevity?

Beyond immunity and blood sugar, maitake is sometimes marketed as a general health supporter, antioxidant, and even "life-extending." It is important to be honest: there are currently no high-quality human evidence that maitake extends life or slows aging. As an edible mushroom, it is certainly a healthy and nutritious addition to the diet, with fiber and active components, but this is fundamentally different from a claim of proven anti-aging benefit.

Another area attracting attention is the possible effect of beta-glucans on blood lipid levels and gut health, due to their fiber content. Here too, the specific evidence for maitake is limited, and most of what is known comes from studies on beta-glucans in general, for example from oat bran. The bottom line is the same across all areas: maitake is an interesting food and supplement with real potential, but expectations should remain modest and based on existing evidence, not marketing.

Should You Start Taking Maitake?

This is exactly why we rated Maitake Yellow. There is a plausible biological mechanism, promising laboratory and animal studies, and a few small human studies, but the evidence is still preliminary and not strong enough to guarantee benefit. Here are the important considerations:

• Caution with diabetes medications, the most critical point. Since maitake may lower blood sugar levels, taking it together with diabetes medications (like metformin, sulfonylureas, or insulin) could cause excessive drops in blood sugar (hypoglycemia). Anyone taking such medications must consult a doctor and monitor blood sugar levels.
• Caution in autoimmune diseases. The stimulating effect on the immune system could be problematic for someone suffering from an autoimmune disease like lupus, multiple sclerosis, or rheumatoid arthritis. In such a situation, a doctor's approval is required.
• Possible effect on blood pressure. A blood pressure-lowering effect has been observed, mainly in animals. Anyone taking blood pressure medications should be aware of this and consult a doctor.
• Extract quality matters. As noted, raw powder is fundamentally different from a standardized beta-glucan extract. If choosing maitake, it is better to choose a product that states the percentage of beta-glucan and the type of extract.
• General safety. Maitake as a food is considered safe for most people, and common side effects are mild, mainly gastrointestinal discomfort. However, long-term safety data on concentrated extracts are lacking.

Additionally, there are groups that need special caution. Pregnant or breastfeeding women should avoid concentrated extracts due to a lack of safety data, and those about to undergo surgery should stop taking it in advance due to the possible effect on blood sugar. As always: the absence of a dramatic warning does not mean the supplement is suitable for everyone.

What Should You Take Away from the Research?

1. If you are taking diabetes medications, do not add maitake without a doctor. The combination could cause excessive drops in blood sugar. This is not theoretical caution, but a real interaction requiring monitoring.
2. Do not expect a simple "immune boost." The best human study showed that maitake affects the immune system in a complex, non-unidirectional way. More is not necessarily better.
3. If you have PCOS, this is an interesting but unproven direction. There is a suggestive study on ovulation induction, but fertility treatment should be managed with a doctor, and maitake is not a substitute for proven therapy.
4. Choose a standardized extract, not cheap powder. Look for a product that states the percentage of beta-glucan and the type of extract, since most studies were done with standardized fractions.
5. Check if you are in a risk group. Autoimmune disease, taking blood thinners or blood pressure medications, pregnancy, breastfeeding, or upcoming surgery are all situations requiring a doctor's approval before taking it.

For those who want to try maitake from a reliable source, you can purchase maitake on iHerb and choose brands that state the beta-glucan percentage and quality testing. To check which supplements are truly suitable for your health goals, including immune system support, according to your age and condition, you can use our personal supplement checker that rates each supplement based on the quality of evidence.

The Broader Perspective

Maitake is a classic example of a medicinal mushroom: a rich tradition, a plausible biological mechanism, and a body of research that is promising but still thin in humans. On one hand, it has real beta-glucans that communicate with our immune system through dedicated receptors, and fractions studied for balancing blood sugar and insulin. On the other hand, most of the strong evidence still comes from the lab and animals, and the best human study actually taught us that the effect is complex and not unidirectional. This is exactly the profile of a yellow supplement: interesting, potential, and relatively safe as a food, but not proven enough to guarantee benefit.

The practical lesson is twofold. First, if you want to try maitake, the most important caution is the interaction with diabetes medications and autoimmune diseases, not the dosage. Second, it is important to remember that no mushroom, no matter how impressive its tradition, replaces the basics. Strong immunity and metabolic health are built from a balanced diet, sleep, physical activity, and control of blood sugar and blood pressure, and maitake can be, at best, a small and safe addition to them. And that is exactly the perspective we hold here: to rate each supplement according to what science actually shows, when it is promising, and when it is better to remain cautious.

References:
Deng G. et al., A phase I/II trial of a polysaccharide extract from Grifola frondosa (Maitake mushroom) in breast cancer patients: immunological effects, Journal of Cancer Research and Clinical Oncology, 2009;135(9):1215-1221 (DOI: 10.1007/s00432-009-0562-z)
Chen J.T. et al., Maitake mushroom (Grifola frondosa) extract induces ovulation in patients with polycystic ovary syndrome, Journal of Alternative and Complementary Medicine, 2010;16(12):1295-1299 (DOI: 10.1089/acm.2009.0696)
Preuss H.G. et al., Fraction SX of maitake mushroom favorably influences blood glucose levels and blood pressure in streptozotocin-induced diabetic rats, Journal of Medicinal Food, 2012;15(10):901-908 (DOI: 10.1089/jmf.2012.0011)