A beta-D-glucan is a dietary fibre. It is a chain of glucose sugars joined by links your body carries no enzyme to cut, wound into a branched shape that belongs to fungi and not to grain. Every number on this page is transcribed from a batch certificate. The rest of it is chemistry.
What a Beta-Glucan Is
A beta-glucan is a chain of glucose molecules joined end to end. Glucose is a simple sugar. Link enough of them together and you no longer have a sugar, you have a polysaccharide, which is a long-chain carbohydrate.
Your body cannot break these particular links. That makes beta-glucan a dietary fibre. It passes through you largely intact, which is the ordinary and unremarkable behaviour of fibre.
The full name, beta-D-glucan, tells you two things. Beta describes the geometry of the bond between one glucose and the next. D describes which of the two mirror-image forms of glucose is used. Both matter, and the first matters most.
Beta-Glucan Foods
Beta-glucans are not rare. They are in your kitchen already. What differs between sources is not whether the fibre is present, but how the chain is put together.
Search interest in beta glucan foods almost always lands on oats. That is fair. Oats are the cheapest and most widely eaten source there is. But an oat beta-glucan and a mushroom beta-glucan are not interchangeable molecules, and the difference is a shape.
The Branch That Separates Fungi
In oats and barley, the glucose units are joined in a long, mostly straight line: beta-(1→3) and beta-(1→4) links, one after another.
In mushrooms and yeast, the backbone is beta-(1→3), and every so often a side chain hangs off it at a beta-(1→6) link. The chain is branched. That branching pattern is the structural signature of a fungal beta-glucan, and it is the reason mushroom beta-glucans are studied as a separate class from cereal ones.
Two labels can both say beta-glucan. One is a chain from a grain, and one is a branched chain from a fungus.
Why Hot Water, Not Alcohol
Beta-glucans are water-soluble. Heat the fruiting body in water and they come out. That is the whole reason hot-water extraction exists, and it is why an extract of turkey tail, whose certificate is dominated by glucans, is made with water and nothing else.
Triterpenoids behave in the opposite way. They do not dissolve in water and need ethanol. A mushroom that carries both, such as reishi or chaga, is therefore extracted twice: once in hot water, once in ethanol, and the two liquids are combined. That is a dual extract, and it is a description of a process, not a grade of quality.
How It Is Measured
This is where the number on a label is either earned or invented.
Glucose chains come in two joineries. Beta is the one in mushroom cell walls. Alpha is the one in starch and glycogen, and starch is what a grain of rice or a kernel of corn is largely made of.
An assay of the kind used for mushroom and yeast beta-glucan, such as the Megazyme K-YBGL method, measures total glucan, then separately measures alpha-glucan, and reports beta-glucan as the difference between the two. It is subtraction. It exists precisely because the two are otherwise easy to confuse.
| What is reported | What it can contain |
|---|---|
| Polysaccharides | Any long-chain carbohydrate. Beta-glucan, alpha-glucan, starch, mannitol. A broad and permissive number |
| Total glucan | Beta plus alpha, together. Higher than beta alone, always |
| Alpha-glucan | Starch and glycogen. In a mushroom product it is usually the grain it was grown on |
| Beta-glucan | Total glucan minus alpha-glucan. The figure worth reading |
The Grain Problem
Some mushroom products are not made from the mushroom. They are made from mycelium grown on grain, the fungal root network cultured on a bed of rice or oats, then dried and milled with the grain still in it.
Grain is starch. Starch is alpha-glucan. A product like that can honestly report a large polysaccharide percentage and a large total glucan percentage while carrying very little of the branched fungal beta-glucan the buyer thinks they are paying for.
If a product reports polysaccharides and not beta-glucan, that is a choice. Ask what the beta-glucan figure is. If a product reports total glucan without the alpha figure beside it, the subtraction has not been shown to you.
Every Alchemy Dose extract is made from the whole fruiting body, never mycelium grown on grain. That sentence is a sourcing statement, and the assay is what makes it checkable.
What Is In Our Extracts
Four extracts carry a glucan figure on the certificate. Each one is transcribed here exactly as the laboratory printed it.
total glucans≥ 47.53%
beta-D-glucans≥ 26.20%
beta-glucans≥ 20.07%
beta-glucans≥ 12.50%
Bars are scaled against the highest disclosed figure, Turkey Tail at 47.53 percent. Turkey Tail's certificate reports total glucans rather than beta-glucan specifically, and it is labelled that way rather than quietly upgraded. Nothing here is an outcome or a promise. These are four numbers, printed on four certificates.
Cordyceps militaris is read on a different axis
Every species is defined by a different compound, and glucan is not the one that defines Cordyceps militaris. Its certificate leads with the two compounds the species is known for, and with the polysaccharide family that carries them.
Polysaccharides ≥ 51.34% · the highest polysaccharide figure in our range
Cordycepin ≥ 0.35% · the nucleoside the species is named for, by HPLC
Adenosine ≥ 0.29% · Mannitol ≥ 21.16%
Reporting cordycepin costs more than reporting a glucan percentage, because it needs chromatography rather than an enzyme assay. It is also the figure that tells you whether you are holding Cordyceps militaris at all.
Figures are stated as disclosed minimums, using the symbol ≥, because a certificate describes the batch that was tested and the next batch is a different batch. A brand that prints a single fixed percentage on every pouch for three years is printing a marketing figure, not a measurement.
What a Beta-Glucan Figure Can Tell You
Search for beta glucan benefits and you will find a great deal of writing about what a fibre might do. This page is about something narrower and more checkable: what the fibre is, where it came from, how a laboratory found it, and how much of it was in the batch you are holding.
- The molecule. A glucose chain your body cannot digest
- The structure. beta-(1→3) backbone, beta-(1→6) branches
- The source. Fungal cell wall, not grain starch
- The method. Total glucan minus alpha-glucan
- The batch. The figure describes the batch that was tested, and is transcribed from its certificate
That is the full extent of what a number on a certificate can honestly do. It is also the part we can prove, and the part almost nobody prints.
Glucans, Polysaccharides, Triterpenoids
Three words that get used interchangeably on labels, and should not be.
When a label says polysaccharides 40 percent, it has told you about the family and not the member. That is not a lie. It is a wider net.
Every Other Compound
A certificate of analysis is a short list of nouns. Here is what each one is, what it does inside the fungus, and why a laboratory bothers to look for it. Nothing in this table is a health claim. It is chemistry, and it is checkable.
Every one of these words appears on a mushroom label somewhere. Only some of them mean what a buyer thinks they mean.
| Compound | What it is | What it does in the fungus | Why it is on a certificate |
|---|---|---|---|
| Beta-D-glucans | A fibre. A long chain of glucose with side chains branching off it. Your body has no tool that can cut those links, so it passes through you | Scaffolding. It builds the cell wall, alongside chitin. It is what holds a mushroom up | The number worth reading. It is the one figure that separates fungal fibre from the grain a product was grown on |
| Polysaccharides | A family name, not a compound. Any long chain of sugar, whatever its shape. Beta-glucan is one member of the family | Found in the cell wall and inside the cell. Every species has them | A wide net. A large polysaccharide figure can be mostly starch. Ask what the beta-glucan number underneath it is |
| Alpha-glucan | The same glucose, joined the other way round. Starch and glycogen. This is the joinery your body can digest | Usually nothing, because it usually is not from the fungus. It is the rice or oats the mycelium was grown on | You subtract it. Beta-glucan is total glucan minus alpha-glucan. A large alpha figure means a large amount of grain in the jar |
| Triterpenoids | Not a fibre. An oil. Bitter enough to taste | Chemical defence. The bitterness that discourages whatever would otherwise eat it | Water will not draw them out. Only ethanol will. Their presence is the entire reason reishi and chaga are extracted twice |
| Ganoderic acids | A named group inside the triterpenoid family, called after the genus Ganoderma | Part of what makes reishi taste bitter | Reishi's identity marker. Measured against an oleanolic acid standard, not by an enzyme assay |
| Betulin | A triterpene the chaga does not make. It draws it from the birch it grows on, the way a plant draws minerals from soil | Nothing. It belongs to the birch. Chaga borrows it | Evidence the chaga grew on birch. A chaga taken from another host tree reads differently |
| Melanin | A pigment. The same family of pigment that colours human skin and hair | Sunscreen and armour. It is why the outer crust looks burnt | It is why chaga is black. A visual identity check, before any assay is run |
| Cordycepin | 3′-deoxyadenosine. A near-copy of adenosine with one piece missing. Not a fibre, not a sugar | A compound only a small number of fungi make. Cordyceps militaris is one of them | Expensive to measure, because it needs chromatography rather than an enzyme. It is the figure that proves the species |
| Adenosine | One of the letters life writes RNA with. It is in every living thing, including you, right now | Ordinary cell chemistry. Nothing about it is special to mushrooms | Reported beside cordycepin because they are chemical siblings and come off the same chromatogram. Adenosine on its own proves nothing |
| Mannitol | A sugar alcohol. Historically called cordycepic acid, which was a misnaming. It is not an acid | The fungus uses it to manage the water inside its cells | One of the largest figures on the cordyceps certificate. Knowing what it is stops the polysaccharide number being read as fibre |
| Hericenones | Aromatic compounds, meaning ring-shaped. Named after Hericium, lion's mane | Present in the mushroom itself, the white shaggy part you would pick | They belong to the fruiting body. A product made from lion's mane mycelium grown on grain cannot carry them |
| Erinacines | Diterpenoids. A different chemical family from hericenones, despite the similar name | Made by lion's mane mycelium in laboratory culture. The mushroom does not make them | The clearest tell in this category. A fruiting-body product cannot honestly print this word. Ours does not |
| PSK and PSP | Polysaccharides with a protein attached. Fibre with a protein bound to it | Fractions isolated from turkey tail, Trametes versicolor | Neither is a routine certificate line. They are named here only so you recognise the words if you meet them elsewhere |
What the published literature actually establishes
Four papers, all indexed on PubMed. Each is cited here for what it measured, not for any outcome in a person.
McCleary and Draga developed the method behind the Megazyme assay. Total glucan is measured after acid hydrolysis, alpha-glucan is measured separately using glucoamylase, and beta-glucan is determined by the difference. Their paper is also where alpha-glucan is defined for this purpose as starch and glycogen, which is why grain in a jar reads as alpha. They further found that Ganoderma lucidum needed the stronger acid to read correctly.
J AOAC Int, 2016. PMID 26957216. DOI
Li and colleagues state the distinction directly: mushroom mycelium has an identity separate from the mushroom, because hericenones are extracted from the fruit body and erinacines from the cultured mycelium. A label that advertises erinacines is describing mycelium, whatever the picture on the front shows. The paper is a rodent feeding study, and we cite it only for that structural statement.
Food Chem Toxicol, 2014. PMID 24810469. DOI
Yu and colleagues compared cultivated Cordyceps militaris against wild Cordyceps sinensis and reported that cordycepin and adenosine content were both higher in the cultivated species. It is the reason our militaris extract discloses cordycepin and our wild Keeda Jadi does not lead with it. We cite this paper for composition only.
J Agric Food Chem, 2006. PMID 16608242. DOI
Guo and colleagues grew Cordyceps militaris fruiting bodies on two different substrates and measured cordycepin, adenosine, polysaccharides and mannitol in each. Every figure moved. Cordycepin was higher on one substrate. Adenosine, polysaccharides and mannitol were higher on the other. Nothing about the species changed. Only what it was grown on.
Which is the whole argument of this page. What a mushroom is grown on ends up in the assay. Ask what the substrate was.
Int J Med Mushrooms, 2016;18(4):327-36. PMID 27481299. DOI
Cordycepin needs chromatography. Beta-glucan needs an enzyme assay. Triterpenoids need ethanol. A brand that reports only one number has told you which test it was willing to pay for.
The Bottom Line
A beta-glucan is a fibre made of glucose. In oats it runs straight. In mushrooms it branches, and the branch is what makes fungal beta-glucan its own thing. It dissolves in hot water, which is why mushroom extracts are made with hot water.
A laboratory finds it by measuring all the glucan, then subtracting the starch. Products built on mycelium grown on grain carry that starch into the jar, which is why the polysaccharide number can be high and the beta-glucan number low.
Ask for the beta-glucan figure and the batch it came from. If a brand cannot give you both, it has told you the answer.
Five Single-Species Extracts
Lion's mane, cordyceps militaris, reishi, chaga and turkey tail. Whole fruiting body, never mycelium grown on grain, every compound figure disclosed per batch.
See the extracts →
