Beta-Glucans Explained: How to Read a Mushroom Supplement Label
Polysaccharides vs beta-glucans: the one number that reveals mushroom supplement quality — and the labelling practice that makes cheap products look potent.
9/26/20265 min read
KNOWLEDGE SERIES
Beta-Glucans Explained: The One Number That Reveals Whether Your Mushroom Supplement Is Actually Working
If you have read a functional mushroom label recently, you have encountered the word "polysaccharides" — almost certainly with a percentage attached. 30% polysaccharides. 40% polysaccharides. Occasionally higher.
It looks like a quality metric. In some products it is. In others it is a number that tells you remarkably little about what you are actually buying.
The reason comes down to a single distinction that the supplement industry has, on the whole, been content to leave unexplained: polysaccharide is a broad category. Beta-glucan is the specific fraction that does the work. And not every product reporting a polysaccharide figure is reporting a beta-glucan figure.
Understanding the difference takes about seven minutes. It will change how you read every mushroom label you encounter from now on.
What Is a Polysaccharide?
A polysaccharide is any molecule built from long chains of sugar units linked together. The word means, literally, "many sugars."
That definition is enormously broad, and the category it describes includes molecules with wildly different biological properties:
Cellulose — the structural polysaccharide of plant cell walls. Humans cannot digest it at all. It passes through as insoluble fibre.
Starch — the glucose storage polysaccharide of grains, potatoes, and most plants. Highly digestible. Rapidly converted to blood glucose.
Glycogen — the glucose storage form in animal liver and muscle.
Chitin — the structural polysaccharide of fungal cell walls and insect exoskeletons.
Beta-glucans — the immune-active polysaccharides of mushrooms and certain cereals.
All five are polysaccharides. They behave completely differently in the human body.
This is why a label stating "40% polysaccharides" is ambiguous on its own. That figure could describe 40% beta-glucan. It could equally describe 40% starch. Without knowing which fraction was measured, the number carries limited information (¹).
What Makes Fungal Beta-Glucans Different
Beta-glucans are polysaccharides in which the glucose units are joined by a beta-glycosidic bond. In fungal beta-glucans specifically, the architecture is a beta-1,3 main chain with beta-1,6 branch points.
That geometry is not a trivial detail. It is the entire reason these molecules do anything.
The human immune system has evolved a receptor called Dectin-1, expressed on the surface of macrophages, dendritic cells, and neutrophils, whose specific function is recognising fungal beta-1,3/1,6-glucans. When Dectin-1 binds a beta-glucan with the correct three-dimensional shape, it triggers an intracellular signalling cascade that activates innate immune responses — stimulating macrophage phagocytosis, promoting natural killer cell activity, and enhancing immune surveillance (²).
This is worth pausing on. Your immune system carries a dedicated molecular detector for a compound found predominantly in fungi. That is not an accident of biology — it reflects a long evolutionary relationship between mammalian immunity and the fungal kingdom.
Dectin-1 mediated activation is the molecular foundation for the immune effects documented across multiple functional mushroom species in clinical research. And it is specific to the beta-1,3/1,6-glucan structure — not to polysaccharides generally.
Alpha-Glucans: The Number That Inflates the Claim
Alpha-glucans are polysaccharides joined by an alpha-glycosidic bond. Starch is an alpha-glucan — specifically alpha-1,4 chains with alpha-1,6 branches. Glycogen is an alpha-glucan.
Alpha-glucans do not bind Dectin-1. They do not activate the immune pathways that fungal beta-glucans activate. From a functional mushroom perspective, they are largely inert — nutritionally they are simply digestible carbohydrate.
Here is where the analytical problem becomes a commercial one.
Many mushroom supplement manufacturers test their products using methods that measure total polysaccharides — a figure that includes both beta-glucans and alpha-glucans without distinguishing them.
When a mycelium-on-grain product reports "40% polysaccharides," that figure may consist of 30% grain starch and 10% beta-glucan. The number on the label is technically accurate. It is also, in terms of what a customer thinks they are buying, close to meaningless.
The McCleary and Draga analytical study referenced in our previous article documented exactly this scenario in commercial products — one sample showing 66.4% alpha-glucan against 3.2% beta-glucan (³).
How to Tell the Difference on a Label
A label stating "30% beta-glucans" is substantially more informative than one stating "40% polysaccharides." Beta-glucan is a defined, specific, measurable fraction. Polysaccharide is a category.
The analytical gold standard for distinguishing the two in mushroom products is the McCleary-Draga method, validated by the Association of Official Analytical Chemists and published in the Journal of AOAC International. It uses sequential enzymatic digestion — first removing alpha-glucans, then measuring what remains — to produce a starch-corrected beta-glucan figure (⁴).
If a brand tests to this standard, it is generally willing to say so. If a brand reports only total polysaccharides and cannot tell you the beta-glucan fraction when asked, that reticence is itself informative.
What 30% Polysaccharides Means in Practice
The mitovito standardisation is 30% polysaccharides in a hot-water fruiting body extract.
The context matters here. In a fruiting body extraction with no grain substrate anywhere in the production chain, the polysaccharide fraction is composed predominantly of fungal beta-glucans. There is no grain starch present to inflate it, because there was never any grain.
Practically, that means 300mg of beta-glucan-rich polysaccharides per gram of extract. A 20g sachet contains 6,000mg of extract, delivering 1,800mg of polysaccharides per serving.
For context on whether that is a meaningful quantity: the Turkey Tail microbiome trial by Pallav and colleagues used 3g of PSP daily. The Shiitake immune trial by Dai and colleagues used 5g to 10g of dried mushroom. Most of the positive clinical trials in the functional mushroom literature operate in dose ranges achievable with one to two mitovito sachets daily (⁵).
One Final Distinction: Cereal Beta-Glucans Are Not Fungal Beta-Glucans
You will encounter beta-glucan supplements derived from oats and barley, typically marketed for cholesterol management.
These are beta-1,3/1,4-glucans — a different linkage pattern from fungal beta-1,3/1,6-glucans. They do not bind Dectin-1 in the same way and have a different biological profile.
The cholesterol-lowering evidence for cereal beta-glucans is genuinely robust and has earned regulatory health claim approval in multiple jurisdictions. That is real science. But it is not the same mechanism, and the two should not be conflated. Structurally similar names, structurally different molecules (⁶).
The Bottom Line
Beta-glucans are the immune-active fraction of functional mushroom extracts. Polysaccharide is a broader category that may or may not reflect beta-glucan content.
When evaluating a mushroom supplement, look for a specified beta-glucan percentage, a stated plant part, and a described extraction method. A number on a label only means something once you know which fraction it measured.
That is not an argument for buying our product specifically. It is an argument for knowing what you are looking at before you buy anyone's.
Sources
(1) Lehninger AL, Nelson DL, Cox MM. (2017). Lehninger Principles of Biochemistry, 7th edition. W.H. Freeman.
(2) Brown GD, Gordon S. (2001). Immune recognition: a new receptor for beta-glucans. Nature, 413, 36–37.
(3) McCleary BV, Draga A. (2016). Measurement of beta-glucan in mushrooms and mycelial products. Journal of AOAC International, 99(2), 364–373.
(4) Ibid.
(5) Pallav K et al. (2014). Gut Microbes, 5(4), 458–467; Dai X et al. (2015). Journal of the American College of Nutrition, 34(6), 478–487.
(6) Zhu F, Du B, Xu B. (2016). A critical review on production and industrial applications of beta-glucans. Food Hydrocolloids, 52, 275–288.
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