Beta-Glucan Percentages on Labels: What the Numbers Mean

Mushroom Supplement Labels

26.3% label accuracy

Only 26.3% of Ganoderma lucidum supplements tested in the U.S. matched their label claims for bioactive ingredients.

Wu et al., Scientific Reports, 2017

13.5-40.9%

beta-glucan range across species

Megazyme K-YBGL

gold standard test method

Structure > Percentage

branching determines activity

Wu et al., Scientific Reports, 2017

View as image ↗

The beta-glucan percentage on a mushroom supplement label is the single number most consumers use to judge quality. It looks objective, scientific, and easy to compare across brands. The problem is that the number by itself tells you very little about what you are actually getting. A 2017 study tested 19 batches of Ganoderma lucidum (reishi) dietary supplements sold in the United States and found that only 26.3% of them matched their labels for bioactive ingredients.^[1] The beta-glucan number on a label depends on the test method used, whether the product is fruiting body or mycelium on grain, how alpha-glucans (starches) are handled, and whether the structural form of the beta-glucan has any immune-activating potential at all.

For help decoding other common label terms, see mushroom label terms decoded. For a step-by-step approach to evaluating labels, see how to read a mushroom supplement label.

What the Beta-Glucan Percentage Actually Measures

When a supplement label states "30% beta-glucans," it means that 30% of the product's dry weight tested positive for beta-glucan using whatever assay the manufacturer chose. The critical word is "whatever." There is no single mandated test for beta-glucan content in dietary supplements, and different methods can yield substantially different numbers for the same product.

McCleary and Draga (2016) developed what is now considered the most robust method, published in the Journal of AOAC International. Their approach measures total glucan through controlled acid hydrolysis with sulfuric acid, then separately measures alpha-glucan (starch and glycogen) using enzymatic hydrolysis. Beta-glucan is calculated as the difference: total glucan minus alpha-glucan.^[2]

This method revealed that different acid protocols produce different results. For most mushroom samples, both hydrochloric acid and sulfuric acid procedures yielded similar beta-glucan values. But for specific species like Ganoderma lucidum (reishi) and Poria cocos, the sulfuric acid method produced markedly higher values.^[2] Assays based entirely on enzymatic hydrolysis generally yielded much lower values than the acid-based procedures, while hydrolysis with trifluoroacetic acid was found to be much less effective than either sulfuric or hydrochloric acid.^[2]

Same Sample, Different Number

How the Hydrolysis Method Moves the Beta-Glucan Result

McCleary & Draga compared several acid and enzyme routes for releasing glucose from beta-glucan. The direction of each result is what they reported — the bars below rank those directions and are not measured percentages.

Sulfuric acid (H₂SO₄)

Reference procedure

Highest recovery

Selected as the best option of all acid and enzyme hydrolysis routes compared. For Ganoderma lucidum and Poria cocos specifically, it returned significantly higher values than HCl.

Hydrochloric acid (HCl)

Optimized alternative

Similar for most samples

Gave similar beta-glucan values to H₂SO₄ across most samples tested — but diverged sharply on the two species above.

Trifluoroacetic acid (2 N TFA)

Acid hydrolysis, 120 °C

Much less effective

Found to be much less effective at hydrolysing beta-glucan than either of the other two acids evaluated.

Fully enzymatic assays

No acid step

Much lower values

Assays based totally on enzymatic hydrolysis generally yielded much lower values than the H₂SO₄ procedure on the same material.

Why this matters on a label: no regulation names a required assay. Two laboratories testing the same batch honestly, using different accepted hydrolysis routes, can print different beta-glucan percentages. A percentage with no method named beside it cannot be compared to another brand's percentage.

Source: McCleary BV, Draga A. Measurement of β-Glucan in Mushrooms and Mycelial Products. J AOAC Int 2016;99(2):364–73. Ranking is schematic; the study reported comparative direction, not a cross-method percentage table.

The practical consequence: two products tested by two different methods could show vastly different beta-glucan percentages despite containing the same raw material. A manufacturer choosing one acid method over another is not committing fraud, but they are making a methodological decision that affects the final number on the label. Without knowing which method was used, comparing beta-glucan percentages across brands is like comparing distances measured in miles versus kilometers without knowing which unit applies.

The Megazyme K-YBGL kit packages McCleary's method for laboratory use, and it is the assay most often named when a mushroom supplement label or certificate of analysis names one at all. That gives it the practical status of a reference method. It is not, however, mandated by any regulatory body for supplement labeling, and no survey has established what share of the market actually uses it — so its prominence is a convention within the quality-focused end of the industry rather than a requirement.

Total Polysaccharides vs. Beta-Glucans: The Inflation Problem

Some supplement labels report "total polysaccharides" instead of or alongside beta-glucan content. These are not the same thing. Total polysaccharides include alpha-glucans (starch, glycogen), chitin, mannans, and other non-beta-glucan carbohydrates. In a mycelium-on-grain product, a large proportion of the polysaccharide content can come from the grain substrate itself, not from the mushroom.

Berger et al. (2022) compared metabolites in mycelium versus fruiting bodies of Agaricus bisporus, Pleurotus ostreatus, and Lentinus edodes. They documented that substrate chemistry, strain, developmental stage, and ecological interactions all produce wide variation in metabolite concentrations in both mycelial cells and fruiting bodies.^[3] When mycelium is grown on grain, the starch from that grain cannot be fully separated from the mycelial tissue during harvest. The resulting product is a mixture of fungal biomass and grain residue, and its "polysaccharide" number reflects both.

Windsor et al. (2025) put this to the test analytically. Comparing wildcrafted chaga canker against North American chaga supplements containing mycelium-fermented grain, they used beta-glucan quantification alongside iodine-starch assays and confirmed a starch-rich composition in the fermented grain products and its absence in authentic chaga canker.^[10] NMR fingerprinting and mass-spectrometry metabolomics showed what the authors described as stark compositional deviations between wildcrafted canker, Inonotus obliquus mycelium, and fermented grain products.^[10] One caveat matters when weighing this evidence: the authors are employed by Nammex, a supplier with a commercial interest in authentic fruiting-body material, and disclosed as much. The analytical methods are standard and the starch finding is chemically unsurprising, but the study was not conducted by a disinterested party.

The McCleary method addresses the inflation problem by separately quantifying alpha-glucan and subtracting it. Not all manufacturers use it. Published figures for how much of a given product's "polysaccharide" number is grain starch versus fungal beta-glucan are not available across the commercial market, because most products are never independently assayed and the assays that do exist are not reported in a standard format. That absence is the point: without an explicit alpha-glucan subtraction, a "total polysaccharides" figure cannot tell you how much beta-glucan you are buying.

What the Umbrella Term Hides

“Total Polysaccharides” vs. Beta-Glucan

A schematic of category membership. Segment sizes are illustrative — no published figure exists for the market-wide split, which is exactly why the umbrella number cannot be converted into a beta-glucan figure.

Counted as “total polysaccharides”

↑ the only part a beta-glucan claim measures

Alpha-glucaninflates the number

starch, glycogen — includes grain substrate residue

Chitininflates the number

structural cell-wall polymer

Mannansinflates the number

other cell-wall carbohydrate

Beta-glucanimmune-active fraction

the fraction with documented immune-modulating activity

The grain problem: when mycelium is grown on grain, the starch from that grain cannot be fully separated at harvest, so it lands inside the alpha-glucan segment and pushes the umbrella number up. A 2025 analysis using iodine-starch assays alongside beta-glucan quantification confirmed a starch-rich composition in mycelium-fermented grain products and its absence in authentic wildcrafted chaga canker.

The fix: the McCleary method measures alpha-glucan separately and subtracts it, reporting beta-glucan by difference. A label that reports a beta-glucan percentage from that assay has done the subtraction. A label reporting only “polysaccharides” has not.

Sources: McCleary BV, Draga A. J AOAC Int 2016;99(2):364–73. Windsor C, et al. Int J Mol Sci 2025;26(7):2970 — authors affiliated with a supplier of fruiting-body material; conflict disclosed in the paper.

For more on what "mycelium biomass" and related terms mean on labels, see mushroom label terms decoded.

How Much Beta-Glucan Is in Different Mushroom Species?

Beta-glucan content varies enormously across species, and even within the same species depending on growing conditions. Mirończuk-Chodakowska et al. (2017) quantified beta-glucan in nine species of edible mushrooms, including both wild-growing and cultivated varieties. Total beta-glucan ranged from 13.5 g/100g dry mass in Agaricus bisporus (portobello) to 40.9 g/100g dry mass in Tricholomopsis rutilans.^[4]

When the researchers measured specifically the 1,3-1,6-beta-D-glucan fraction (the structure most associated with immune activity), the picture shifted. This immunologically relevant fraction ranged from just 3.9 g/100g dry mass in Agaricus bisporus (cremini) to 16.8 g/100g in Auricularia auricula-judae (wood ear).^[4] Wild-growing species had generally higher 1,3-1,6-beta-D-glucan content than cultivated species.^[4]

The ratio between total beta-glucan and the 1,3-1,6 fraction is telling. The species with the greatest proportion of their total beta-glucan in the immunoactive 1,3-1,6 form were Gyroporus cyanescens (54%), Suillus granulatus (49.8%), Auricularia auricula-judae (47.9%), and Suillus variegatus (40.6%).^[4] The study reported these four as the top performers on that measure but did not publish the ratio for every species tested, so the low end of the range is not established. What the data does establish is that the fraction varies substantially between species. A supplement label showing "30% beta-glucan" from one species may contain less immunoactive glucan than a product showing "20% beta-glucan" from another, because the proportion of the biologically relevant structural form differs.

The Fraction Inside the Fraction

Total Beta-Glucan Is Not the Same as Immunoactive Beta-Glucan

Nine species measured — eight wild-growing Polish species plus cultivated Agaricus bisporus for comparison. Grams per 100 g dry mass.

Total beta-glucan

13.5

g/100g

40.9

g/100g

Agaricus bisporus (portobello, cultivated)

Tricholomopsis rutilans (wild)

Immunoactive 1,3-1,6 fraction

3.9

g/100g

16.8

g/100g

Agaricus bisporus (cremini, cultivated)

Auricularia auricula-judae (wood ear)

Share of total beta-glucan that is the 1,3-1,6 form

The four species reported with the greatest share. Even the best performer keeps barely half its beta-glucan in the immunologically relevant structure.

Gyroporus cyanescens

cornflower bolete

54.0%

Suillus granulatus

weeping bolete

49.8%

Auricularia auricula-judae

wood ear

47.9%

Suillus variegatus

velvet bolete

40.6%

Dashed line marks 50%.

Why this matters on a label: a “total beta-glucan” percentage bundles together the branched 1,3-1,6 structure that engages immune receptors and other beta-linked glucan that does not. Because that split varies by species, a higher headline percentage from one mushroom can deliver less immunoactive glucan than a lower percentage from another.

Source: Mirończuk-Chodakowska I, et al. Quantitative evaluation of 1,3,1,6 β-D-glucan contents in wild-growing species of edible Polish mushrooms. Rocz Panstw Zakl Hig 2017;68(3):281–290. Values as published; the study reported only the four highest ratios, so no minimum ratio is shown.

Only 26% of Tested Reishi Supplements Match Their Labels

Wu et al. (2017) published findings in Scientific Reports that should concern anyone relying on supplement labels. They purchased 19 batches of Ganoderma lucidum products in the United States and evaluated them for triterpenes and polysaccharides using chromatographic methods and saccharide mapping. Only 5 of 19 tested samples (26.3%) had measured ingredients consistent with their labels.^[1]

These were products commercially available to American consumers, marketed as Red Reishi or Reishi. The paper does not break down which direction each failing product deviated in, or name the brands, so the finding should be read as a market-level quality signal rather than a verdict on any particular product. What the researchers did conclude is that quality consistency of G. lucidum dietary supplements in the U.S. market was poor and should be carefully investigated.^[1] The work carries some institutional weight on this point: two of the co-authors were affiliated with the United States Pharmacopeial Convention, the standards body that publishes supplement quality monographs.

The underlying issue is that the U.S. FDA does not require pre-market testing of dietary supplement ingredient claims. Under the Dietary Supplement Health and Education Act (DSHEA) of 1994, manufacturers are responsible for their own quality testing. The FDA can act against products found to be adulterated or misbranded after they reach the market, but there is no pre-approval process for verifying that the beta-glucan percentage on a label is accurate before the product is sold.

Third-party certification programs (NSF International, USP, ConsumerLab) provide independent verification of supplement contents, but participation is voluntary and adds cost. Products bearing these certifications have been tested against their label claims by an outside laboratory, which provides more confidence than manufacturer self-testing alone.

Newer Testing Methods Improve Specificity

The limitations of existing assays have driven development of more specific detection methods. Kanno et al. (2020) developed a novel protein-based assay using a recombinant beta-glucan-binding protein (supBGRP) that specifically recognizes (1→3)-beta-D-glucans. The protein did not react to barley glucan, dextran, mannan, pustulan, or xylan, but did react to fungal beta-glucans from six edible mushroom species including Pleurotus ostreatus, Grifola frondosa, Lentinus edodes, and Auricularia polytricha.^[5]

The supBGRP approach was particularly effective at detecting alkaline-extracted beta-glucan from Lentinus edodes (shiitake), outperforming polyclonal antibody methods for that fraction.^[5] As a recombinant protein, it offers advantages over antibodies in terms of availability and stability as a reagent molecule.^[5]

This matters because more specific testing can distinguish between beta-glucan structures that activate immune pathways and those that do not. The Megazyme method tells you the total beta-glucan content. Protein-based assays like supBGRP may eventually tell you the proportion of that content that is biologically relevant.

Structure Matters More Than Percentage

A 2010 study by Volman et al. tested beta-glucan-rich polysaccharide extracts from five mushroom species on bone marrow-derived macrophages and intestinal Caco-2 cells. The results showed dramatic differences in immune activation despite all extracts containing beta-glucans. Agaricus bisporus extracts stimulated nitric oxide production by macrophages, while extracts from Agaricus blazei and Phellinus linteus had no effect at all.^[6]

Structural analysis comparing A. bisporus and A. blazei suggested that branching of the beta-glucan chain is essential for immune-stimulating activity.^[6] Two products with identical beta-glucan percentages can produce fundamentally different biological effects if their branching patterns differ.

Anaya et al. (2023) confirmed this at the receptor level. Their biophysical study showed that Dectin-1 signaling depends on beta-glucan tertiary and quaternary structure, not just chemical identity. Their denaturation experiments produced the sharpest finding in this entire literature: glucan structure determines agonistic potential but not receptor binding affinity.^[7] A denatured glucan still binds Dectin-1 about as well as a structured one; it simply fails to drive the receptor clustering that starts the signal.^[7] This is why extraction and processing methods that alter beta-glucan structure can reduce immune-activating potential without changing the measured beta-glucan percentage — and why no assay that counts glucose units can detect the difference.

A 2021 review in Nutrients frames why the source matters structurally: mushroom cell walls carry beta-glucans with both β-1,3 and β-1,6 linkages, which give them their linear and branching architecture, whereas cereal beta-glucans have no 1,6 linkages and no branching at all.^[8] The review describes immunomodulatory and anti-inflammatory effects of mushroom beta-glucans in cellular and experimental models, and notes that the cardiovascular and metabolic benefits established for oat and barley beta-glucans still require confirmation in human studies using mushroom beta-glucans.^[8] Evidence about one kind of beta-glucan does not automatically transfer to another. For more on how molecular weight specifically affects biological activity, see beta-glucan molecular weight and biological activity.

What Trained Immunity Research Tells Us About Labels

Case et al. (2024) demonstrated that whole mushroom powder from common Agaricus bisporus (button mushrooms) could drive trained immunity in mouse models, with oral administration shifting bone marrow progenitor populations toward myeloid-committed cells.^[9] Enriching for beta-glucan content through chemical fractionation boosted the trained response, and the size of the response tracked the amount of available beta-glucan in the powder.^[9] The authors were explicit about the magnitude: training from whole mushroom powder was modest compared with the training produced by yeast-derived beta-glucans.^[9] The powdered mushroom products used in the study were supplied by a commercial mushroom producer, two of whose scientists are co-authors.

Simulated in vitro digestion of the mushroom powder retained beta-glucans (verified by NMR) and preserved the capacity to train human monocytes.^[9] This suggests that beta-glucans in whole food form, when present in their natural structural context, can be biologically active even without the high-percentage extract numbers that supplement marketing emphasizes.

The implication for label reading is narrower than it might first appear. Case et al. found that the trained response tracked the amount of available beta-glucan, so quantity clearly matters. But Anaya et al. found that structure determines whether a beta-glucan can trigger Dectin-1 signaling at all, independent of how tightly it binds. Put together, the two results say that a percentage is a necessary input to predicting activity but not a sufficient one: processing that degrades structure can lower activity without lowering the measured number.

No study has directly compared a whole-fruiting-body product against a structurally degraded high-percentage extract in the same experiment, so the question of which one a consumer should prefer at equal cost has not been answered empirically. What the evidence does establish is that whole mushrooms deliver beta-glucans in their native structural context, and that this context survives simulated digestion. It does not establish that eating button mushrooms is equivalent to taking a concentrated supplement — the Case results point the other way on magnitude — but it does undercut the assumption that a higher label percentage is automatically the better product.

For more on how beta-glucans interact with the gut immune system after ingestion, see beta-glucan bioavailability. For practical solutions to bioavailability challenges, see improving mushroom compound bioavailability.

The Bottom Line

The beta-glucan percentage on a mushroom supplement label is a starting point, not a verdict. It depends on which test method was used, whether alpha-glucans were subtracted, whether the source is fruiting body or mycelium on grain, and whether the beta-glucan retains the (1,3)-(1,6) branching structure that activates immune cells. Only 26.3% of reishi supplements tested in the U.S. matched their label claims. The deepest limitation is structural: because a denatured beta-glucan still binds Dectin-1 without triggering it, no assay that counts glucose units can tell you whether the beta-glucan in the bottle still works. Until standardized testing and labeling requirements exist, the number on the label is best understood as one data point among many — and none of the evidence above establishes a health outcome from any particular percentage.

Frequently Asked Questions

What is a good beta-glucan percentage in a mushroom supplement?

There is no established threshold, because no regulator or standards body has set one. For context on what the raw material contains: a 2017 Polish study measuring whole dried fruiting bodies found total beta-glucan ranged from 13.5 g/100g dry mass in cultivated Agaricus bisporus up to 40.9 g/100g in wild Tricholomopsis rutilans. Concentrated extracts are a different matter and are not covered by those figures. More useful than chasing a number is checking that the figure came from a validated assay such as the Megazyme K-YBGL method, which subtracts alpha-glucan (starch) rather than counting it.

What is the difference between polysaccharides and beta-glucans on a mushroom label?

Total polysaccharides is an umbrella term covering starch, glycogen, chitin, mannans, and other carbohydrates alongside beta-glucans. Beta-glucan is the specific fraction with documented immune-modulating activity. The distinction matters most for mycelium-grown-on-grain products: 2025 analytical work using iodine-starch assays confirmed a starch-rich composition in mycelium-fermented grain products that was absent in authentic wildcrafted material. There is no published market-wide figure for how much of a typical "total polysaccharides" claim is grain starch, which is precisely why the umbrella number cannot be used to estimate beta-glucan content.

How is beta-glucan tested in mushroom supplements?

The most validated method is the Megazyme K-YBGL assay, developed by McCleary and Draga (2016). It measures total glucan via acid hydrolysis, then subtracts alpha-glucan measured via enzymatic hydrolysis. The result is beta-glucan by difference. Different acid types (sulfuric, hydrochloric, trifluoroacetic) yield different numbers for the same product.

Do mushroom supplement labels accurately reflect beta-glucan content?

Often not. Wu et al. (2017) tested 19 batches of reishi supplements sold in the United States and found that only 26.3% matched their label claims for bioactive ingredients. The dietary supplement industry in the U.S. does not require pre-market verification of ingredient claims. Third-party testing provides independent checks but is voluntary.

Is mycelium on grain lower in beta-glucans than fruiting body?

The grain substrate dilutes it. Mycelium grown on grain cannot be fully separated from that grain during harvest, so the finished product contains grain starch (an alpha-glucan) that adds to a "total polysaccharide" figure without contributing immunoactive beta-glucan. Analytical work published in 2025 confirmed the starch-rich signature of mycelium-fermented grain products and its absence in authentic wildcrafted material — though that study's authors are affiliated with a supplier of fruiting-body material, which is worth weighing. The honest summary is that grain-grown mycelium products carry a known diluent, not that every fruiting-body product outperforms every mycelium product.

Does a higher beta-glucan percentage mean a better supplement?

Not by itself. Branching pattern and tertiary structure determine immune-activating potential alongside the total percentage. A 2010 study found Agaricus bisporus extracts stimulated nitric oxide production by macrophages while Agaricus blazei and Phellinus linteus extracts had no effect at all, despite all of them containing beta-glucans. A 2023 biophysical study went further and showed that denatured beta-glucans still bind the Dectin-1 receptor but fail to trigger it. A percentage counts glucose units; it cannot see structure.

Can I use the beta-glucan percentage to compare two different brands?

Only with caution, and only if both disclose their test method. Because there is no mandated assay, one manufacturer may use a sulfuric acid hydrolysis method and another a purely enzymatic one — and the 2016 McCleary and Draga work found enzymatic assays generally return much lower values than the sulfuric acid procedure on the same material. Two honest labs testing identical material can therefore print different numbers. If neither label names its method, the two percentages are not directly comparable.

Sources & References

1. 1RTHM-00499·Wu, Ding-Tao et al. (2017). “Evaluation on quality consistency of Ganoderma lucidum dietary supplements collected in the United States..” Scientific reports.Study breakdown →PubMed →↩
2. 2RTHM-00438·McCleary, Barry V et al. (2016). “Measurement of β-Glucan in Mushrooms and Mycelial Products..” Journal of AOAC International.Study breakdown →PubMed →↩
3. 3RTHM-00743·Berger, Ralf G et al. (2022). “Mycelium vs. Fruiting Bodies of Edible Fungi-A Comparison of Metabolites..” Microorganisms.Study breakdown →PubMed →↩
4. 4RTHM-00484·Mirończuk-Chodakowska, Iwona et al. (2017). “Quantitative evaluation of 1,3,1,6 β-D-glucan contents in wild-growing species of edible Polish mushrooms..” Roczniki Panstwowego Zakladu Higieny.Study breakdown →PubMed →↩
5. 5RTHM-00625·Kanno, Takashi et al. (2020). “Quantification of β-Glucan from Culinary-Medicinal Mushrooms Using Novel Artificial β-Glucan Recognition Protein..” International journal of medicinal mushrooms.Study breakdown →PubMed →↩
6. 6RTHM-00200·Volman, Julia J et al. (2010). “Effects of mushroom-derived beta-glucan-rich polysaccharide extracts on nitric oxide production by bone marrow-derived macrophages and nuclear factor-kappaB transactivation in Caco-2 reporter cells: can effects be explained by structure?.” Molecular nutrition & food research.Study breakdown →PubMed →↩
7. 7RTHM-00814·Anaya, Eduardo U et al. (2023). “Dectin-1 multimerization and signaling depends on fungal β-glucan structure and exposure..” Biophysical journal.Study breakdown →PubMed →↩
8. 8RTHM-00676·Cerletti, Chiara et al. (2021). “Edible Mushrooms and Beta-Glucans: Impact on Human Health..” Nutrients.Study breakdown →PubMed →↩
9. 9RTHM-00867·Case, Sarah et al. (2024). “β-glucans from Agaricus bisporus mushroom products drive Trained Immunity..” Frontiers in nutrition.Study breakdown →PubMed →↩
10. 10RTHM-02209·Windsor, Coleton et al. (2025). “What This 2025 Chaga Supplement Authentication Study Actually Found.” International journal of molecular sciences.Study breakdown →PubMed →↩