Does Agaricus blazei mushroom boost the immune system?

Most medicinal mushrooms share the ability to modulate immunity through beta-glucans, but Agaricus blazei has an unusually high concentration of beta-1,3-D-glucan and beta-1,6-D-glucan — the branched polysaccharide structures that bind to pattern recognition receptors on immune cells¹. This binding activates a cascade: monocytes, dendritic cells, and NK cells all increase their activity and cytokine output. The result is a shift toward what researchers call Th1 immune dominance — broadly associated with antiviral, antibacterial, and antitumor responses.

Beyond beta-glucans, Agaricus blazei contains ergosterol (a precursor to vitamin D2), ergothioneine (a rare antioxidant amino acid concentrated in mushrooms), and various proteoglucans with direct cytotoxic activity against cancer cell lines in laboratory studies⁶.

Immune Support and Cancer Adjunct Use

Agaricus blazei is used as a complementary supplement by cancer patients in Japan and Brazil, particularly alongside chemotherapy. The rationale is that chemotherapy suppresses immune function, and mushroom-derived beta-glucans may help preserve natural killer cell activity during treatment².

In a 100-patient trial of gynecological cancer patients undergoing carboplatin-based chemotherapy, those who also took Agaricus blazei Murill Kyowa extract showed significantly higher NK cell activity than the placebo group (p < 0.002). Self-reported quality of life scores were also better in the mushroom group². This is an adjunct use, not a replacement for treatment.

Blood Sugar and Metabolic Effects

In people with type 2 diabetes already taking metformin and gliclazide, adding an Agaricus blazei extract for 12 weeks improved insulin resistance markers more than placebo³. The proposed mechanism involves beta-glucan-mediated improvements in insulin receptor signaling and glucose uptake in peripheral tissues, similar to mechanisms observed with other beta-glucan-rich foods like oats and barley.

Forms and Dosage

Agaricus blazei is available as:

• Dried powder or capsules (standardized extracts typically 500–1500 mg/day in studies)
• The AndoSan liquid extract (used in Norwegian clinical trials), which contains 82% Agaricus blazei Murill
• The Agaricus blazei Murill Kyowa (ABMK) extract used in Japanese trials

Most clinical trials have used 900 mg to 1500 mg/day of dry extract for 8–12 weeks. Look for products standardized to beta-glucan content rather than just dried mushroom weight. Both the fruiting body and mycelium contain bioactive compounds, though most research uses fruiting body extracts⁶.

Considerations

Agaricus blazei is generally well tolerated in published trials. Avoid it if taking immunosuppressant medications (such as after organ transplant), as the immune-stimulating effect could counteract those drugs. Rare cases of elevated liver enzymes have been reported — mostly with unregulated products from unknown suppliers. People with autoimmune conditions should consult a clinician before using¹.

See our Turkey Tail page for another mushroom with clinical immune evidence, or our Reishi page for immune-modulating mushrooms with a different mechanism of action.

NK Cell Activity in Gynecological Cancer Patients

Ahn et al. (2004) conducted the most cited clinical study on Agaricus blazei Murill Kyowa (ABMK) in human oncology. One hundred patients with cervical, ovarian, or endometrial cancer undergoing chemotherapy (carboplatin plus etoposide or carboplatin plus taxol, every 3 weeks for at least 3 cycles) were randomized to receive ABMK extract or placebo alongside their treatment.

NK cell activity was significantly higher in the ABMK group compared to placebo (p < 0.002). Of the three treatment arms, the greatest NK cell preservation was seen in patients receiving carboplatin plus etoposide with ABMK. Quality of life scores, measured using a validated instrument, were also better in the supplemented group. This was not a blinded trial and NK cell activity is a proxy endpoint, not a survival outcome, which limits interpretation. Nevertheless, it remains the most direct human evidence for immune preservation during chemotherapy².

Multiple Myeloma and High-Dose Chemotherapy

Tangen et al. (2015) ran a randomized, double-blinded, placebo-controlled trial in 40 multiple myeloma patients scheduled for high-dose chemotherapy with autologous stem cell transplantation — one of the most immunologically depleting treatments in oncology⁴. Patients received either AndoSan (82% Agaricus blazei extract) or placebo for approximately 7 weeks starting at stem cell mobilization.

In the AndoSan group, leukapheresis products showed increased percentages of regulatory T cells (Tregs) and plasmacytoid dendritic cells. Serum levels of IL-1ra, IL-5, and IL-7 were significantly elevated at end of treatment compared to placebo. IL-1ra (an endogenous anti-inflammatory cytokine) and IL-7 (a lymphocyte survival factor) are particularly relevant in the context of post-transplant immune reconstitution. The clinical significance of these immunological shifts for long-term outcomes requires larger powered studies⁴.

Blood Sugar and Insulin Resistance

Hsu et al. (2007) conducted a 12-week randomized, double-blinded, placebo-controlled trial in patients with type 2 diabetes already receiving stable doses of metformin and gliclazide³. Participants in the Agaricus blazei group showed significantly greater reductions in insulin resistance (measured by HOMA-IR) than the placebo group. Fasting blood glucose and postprandial glucose also trended lower, though the trial was relatively small and follow-up was short.

The proposed mechanism involves polysaccharide fractions that enhance insulin receptor sensitivity and reduce hepatic glucose output, analogous to the metabolic effects seen with high-beta-glucan cereals. This is complementary use alongside existing diabetes medications — not a standalone treatment³.

Inflammatory Cytokines in Elderly Women

Lima et al. (2012) enrolled 57 elderly women in a randomized, double-blind, placebo-controlled trial to test whether Agaricus blazei dry extract (900 mg/day for 60 days) would alter serum levels of IL-6, IFN-γ, and TNF-α⁵. This was the first RCT in a general non-cancer population.

No statistically significant changes were observed in any of the three cytokines in the AbM group versus placebo. The authors noted this null result contrasted with animal studies, and proposed that the modest dose, short duration, or the specific cytokine panel chosen may have been insufficient to capture the immune effects seen in other populations. This study is an important caution against overgeneralizing the immune-stimulation narrative to all populations and outcomes⁵.

Mechanisms: Beta-Glucan and Innate Immunity

Hetland et al. (2011) reviewed the mechanistic literature on Agaricus blazei extract's effects on innate immunity, drawing on both in vitro and in vivo work¹. The dominant mechanism is beta-glucan binding to Dectin-1 receptors on monocytes, dendritic cells, and NK cells, triggering cytokine production (particularly TNF-α, IL-6, and IL-12). This activates a Th1-skewed immune response and promotes trained immunity — a form of epigenetic reprogramming that enhances innate immune memory.

The extract also showed anti-allergy properties in animal models by suppressing IgE production and Th2 cytokines (IL-4, IL-5, IL-13), which are elevated in allergic conditions. This Th1/Th2 rebalancing effect is a proposed mechanism for the anti-inflammatory actions observed in clinical studies of inflammatory bowel conditions¹.

Composition Summary

Huang et al. (2022) published a comprehensive review of Agaricus blazei's chemical composition and health properties⁶. The fruiting body contains 40–45% carbohydrates (predominantly beta-glucans), 35–40% protein, and a range of bioactive phenolics including p-hydroxybenzoic acid and catechin derivatives. The ergothioneine content — a sulfur-containing antioxidant — is particularly notable, with Agaricus blazei having among the highest concentrations of any edible mushroom. Ergothioneine is taken up by dedicated transporters in human cells and accumulates in tissues under oxidative stress, suggesting a role in cellular protection independent of the immune effects.

Strength of Evidence

The current evidence is best described as suggestive but not conclusive. The NK cell data in cancer patients is consistent across multiple studies but uses proxy endpoints. The diabetes RCT is small. The AndoSan multiple myeloma trial measured immune biomarkers, not disease outcomes. No trial is large enough to demonstrate effects on cancer survival, infection rates, or long-term metabolic outcomes. The null finding in healthy elderly women underscores that immune effects may be context-dependent — most pronounced when the immune system is under stress. This is a pattern seen across medicinal mushroom research more broadly.