Agaricus blazei Murill (AbM), also known as Himematsutake or the “royal sun mushroom,” is a basidiomycete fungus native to the Atlantic coast of Brazil. First brought to scientific attention in the 1970s, it has since accumulated a meaningful body of research focused on its immunomodulatory compounds. While much of the early work was preclinical, more recent studies include human trials that help clarify both the potential and the limitations of this mushroom.
What Makes Agaricus Blazei Biologically Active?
The primary bioactive constituents of Agaricus blazei are polysaccharides, particularly beta-(1,3) and beta-(1,6)-glucans. These structural carbohydrates interact with pattern recognition receptors on immune cells, including dectin-1 and toll-like receptors, initiating downstream signaling cascades that modulate innate immune activity.
Research reviewing polysaccharides from Basidiomycetes, including AbM, notes that beta-1,3-glucans with beta-1,6-glucose side chains appear to have notable roles in immunomodulating and antitumor activities in laboratory and animal models.[1] Beyond glucans, AbM also contains ergosterol (a precursor to vitamin D2), lectins, and various polysaccharide-protein complexes that may contribute to its biological profile.
Innate Immunity and Cytokine Activity
One of the better-characterized effects of AbM involves its interaction with innate immune cells. Studies have shown that AbM extracts may stimulate monocytes, natural killer (NK) cells, and dendritic cells. In vitro work with monocyte-derived dendritic cells found that an AbM-based extract (AndoSan) promoted dose-dependent increases in proinflammatory and chemotactic cytokines, including IL-8, G-CSF, TNF-alpha, and IL-1beta, suggesting immune cell activation rather than suppression.
A broader review of AbM’s mechanisms concluded that the mushroom may elicit effects across tumor surveillance, infection response, allergy modulation, and inflammation through its influence on innate immunity and its potential to ameliorate imbalances in Th1/Th2 immune polarization.[2] These findings come primarily from animal models and in vitro systems, and extrapolation to human outcomes should be approached with appropriate caution.
NK Cell and Splenocyte Effects in Animal Models
Animal studies using isolated beta-(1,3)-glucan fractions from AbM have reported augmented NK cell activity and increased production of immune-signaling molecules, including IL-12, TNF-alpha, and IL-18, in tumor-bearing mice. These compounds appear to support immune surveillance activity in controlled laboratory settings, though such models do not directly translate to human clinical outcomes.
Human Clinical Data: What the Trials Show
A randomized, single-blinded, placebo-controlled trial investigated an AbM-based extract (AndoSan) in 50 patients with symptomatic Crohn’s disease (CD) over 21 days. Patients in the AndoSan group showed significant improvement in symptom scores from baseline (days 0 to 14 and 21), though the between-group difference compared to placebo did not reach statistical significance (p = 0.106). The researchers noted that patients with mild to moderate symptoms may have beneficiary effects as a safe supplement alongside conventional treatment, and no harms or unintended effects were reported.[3]
A companion study from the same trial examined cytokine profiles in both Crohn’s disease and ulcerative colitis patients after AndoSan consumption. Results indicated limited but measurable reductions in systemic cytokine levels, with the effect most notable for IL-2 and IL-5 in the ulcerative colitis group. The authors suggested that anti-allergic and antioxidant mechanisms, rather than direct cytokine modulation, may play a more central role in the clinical effects observed.[4]
These human studies are preliminary and involve a proprietary extract. Broader conclusions about AbM supplements in general require larger, well-controlled trials across diverse populations.
Antioxidant Properties
Beyond immune activity, Agaricus blazei contains compounds with antioxidant potential, including phenolic acids, ergosterol, and polysaccharide-protein complexes. Oxidative stress is a contributing factor in numerous chronic conditions, and compounds that may reduce free radical burden have attracted research interest. However, studies specifically examining AbM’s antioxidant effects in humans remain limited, and most data comes from cell-based or animal experiments.
Traditional Use Context
In Brazil, communities in the Piedade region of Sao Paulo state have historically consumed AbM as a food and tonic, associating it with low rates of certain chronic diseases. This observation helped spark early scientific interest, though epidemiological observations of this kind cannot establish causation and are subject to numerous confounding variables.
In Japan, AbM became a widely used health food product through the 1980s and 1990s, and it remains one of the more commercially prominent medicinal mushrooms in East Asian markets. Its use in traditional Japanese herbal practice (Kampo) is more recent than classical Chinese medicinal mushrooms like Reishi or Chaga, but interest in its pharmacological properties has generated substantial research output since the 1990s.
Supplement Considerations
AbM supplements are commercially available as dried powder, capsules, and water or ethanol extracts. Extraction method matters: hot water extraction is most commonly used to release polysaccharide content, while alcohol extraction may be used to concentrate other compounds. When evaluating a supplement, looking for beta-glucan content on the certificate of analysis provides a more meaningful metric than total polysaccharide weight alone.
For a deeper look at how to evaluate what functional mushroom supplement labels actually mean, see our guide on How to Read a Mushroom Supplement Label: Beta-Glucans and Polysaccharides Explained.
As with other functional mushrooms, individuals taking immunosuppressant medications or undergoing chemotherapy should consult a qualified healthcare provider before adding AbM to their routine, as its immunostimulatory properties may interact with these treatments.
Summary
Agaricus blazei Murill is a functional mushroom with a growing body of preclinical and early clinical research supporting its immunomodulatory properties. Its beta-glucan content appears to engage innate immune cells in meaningful ways in laboratory settings, and at least one randomized human trial suggests potential benefits for inflammatory bowel conditions, though larger confirmatory studies are needed. It represents a scientifically credible mushroom species worth attention, with realistic expectations calibrated to the current state of the evidence.
References
- 1. Mizuno M, Nishitani Y. Immunomodulating compounds in Basidiomycetes. J Clin Biochem Nutr. 2013;52(3):202-7. PMID 23704809
- 2. Hetland G, Johnson E, Lyberg T, Kvalheim G. The Mushroom Agaricus blazei Murill Elicits Medicinal Effects on Tumor, Infection, Allergy, and Inflammation through Its Modulation of Innate Immunity and Amelioration of Th1/Th2 Imbalance and Inflammation. Adv Pharmacol Sci. 2011;2011:157015. PMID 21912538
- 3. Therkelsen SP, et al. Effect of the Medicinal Agaricus blazei Murill-Based Mushroom Extract, AndoSan, on Symptoms, Fatigue and Quality of Life in Patients with Crohn’s Disease in a Randomized Single-Blinded Placebo Controlled Study. PLoS One. 2016;11(7):e0159288. PMID 27415795
- 4. Therkelsen SP, et al. Cytokine Levels After Consumption of a Medicinal Agaricus blazei Murill-Based Mushroom Extract, AndoSan, in Patients with Crohn’s Disease and Ulcerative Colitis in a Randomized Single-Blinded Placebo-Controlled Study. Scand J Immunol. 2016;84(6):323-331. PMID 27588816
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Functional mushroom supplements are not intended to diagnose, treat, cure, or prevent any disease. Consult a qualified healthcare provider before starting any new supplement, especially if you have a medical condition or are taking medications.
