Beta-glucans are the active class
Functional mushrooms are studied mainly for their polysaccharides, and specifically beta-glucans — complex sugars that make up the mushroom's cell walls.
Beta-glucans are recognised by receptors on immune cells. That recognition is why they are described as immune-modulating rather than immune-boosting: the interaction adjusts activity rather than simply increasing it, which is the more accurate and less exciting description.
Because beta-glucan content is measurable, it is the honest basis for comparing mushroom products. A label that states beta-glucan percentage is telling you something. One that states only "polysaccharides" may be counting the starch from the growing substrate — which brings us to the important part.
Fruiting body versus mycelium on grain
This is the distinction that matters most, and it is worth being precise about.
The fruiting body is the mushroom itself — the part you would recognise. It is where beta-glucan concentration is highest.
The mycelium is the root-like network the fungus grows through its substrate. Mycelium is legitimate fungal tissue. The problem is commercial: mycelium is typically grown on sterilised grain, and at harvest the mycelium and the grain cannot practically be separated. The product is milled together.
The result — often labelled myceliated grain or listed with terms like "mycelial biomass" — can be substantially starch by weight. If the label reports total polysaccharides, that starch counts toward the number. Beta-glucan content can be a small fraction of what a fruiting-body extract delivers.
Fruiting body, an extract rather than raw powder, and a stated beta-glucan percentage — not "polysaccharides". Those three words on a label do more work than any claim beside them.
Why extraction matters
Mushroom cell walls are made of chitin — the same material as insect shells — and it is not readily digestible. Raw milled mushroom is largely locked inside a container the digestive system struggles to open.
Hot water extraction is the traditional and appropriate method for beta-glucans, which are water soluble; it is essentially a long, controlled simmer. Some compounds are alcohol soluble instead, which is why dual extraction exists.
The practical version: "extract" on a label is meaningfully better than "powder", and the extraction ratio tells you how concentrated it is.
The three mushrooms
Turkey tail (Trametes versicolor)
The most studied of the three. Its beta-glucan fractions have been investigated for immune modulation for decades, largely in human medicine, and it has been the subject of small veterinary research as well. Treat the veterinary literature as early rather than settled — the studies that exist are small, and immune modulation is a mechanism, not an outcome.
Reishi (Ganoderma lucidum)
Long traditional use and a substantial laboratory literature on immune signalling and stress response. Human clinical work is mixed and dog-specific research is limited. Reishi is bitter, which is a genuine formulation constraint in a product an animal has to willingly eat.
Lion's mane (Hericium erinaceus)
Studied mostly for compounds — hericenones and erinacines — investigated in relation to nerve growth factor. Nearly all of that work is cell culture and rodent research. It is an interesting mechanism at an early stage, and describing it as proven cognitive support in dogs would be getting well ahead of the evidence.
Stated plainly: research on these ingredients is not a claim about any finished product, and none of these mushrooms treat, cure or prevent disease in dogs. An animal with a diagnosed condition needs veterinary care, and mushroom supplements should be discussed with a vet before use alongside medication.
Are mushrooms safe for dogs?
The question usually carries an unspoken worry about wild mushroom poisoning, which is a real and serious danger — and entirely separate. Cultivated culinary and functional mushroom species used in supplements are not the toxic wild species that poison dogs on walks.
The species above are generally well tolerated. As with any supplement, discuss it with your veterinarian if your dog is on medication — immune-modulating ingredients in particular deserve a conversation if your animal takes immunosuppressants or has an autoimmune condition.
How this fits a formula
In our dog formula the mushroom blend is the botanical layer, sitting alongside a peptide blend as the signalling layer and an elk blend as the whole-food nutritional base. Three ingredients, three jobs.
Our cat formula does not use the same blend — cats need a different base, for reasons we cover in the piece on taurine.
Frequently asked
Powder is dried, milled mushroom. Extract has been processed — usually with hot water — to pull the beta-glucans out of the indigestible chitin cell wall and concentrate them. Extract is generally the more useful form, and the extraction ratio tells you how concentrated.
Organic certification speaks to how something was grown, not to what is in it. Organic myceliated grain is still largely grain. Fruiting body versus mycelium-on-grain is the more important axis, and the two labels are frequently confused deliberately.
They can, which is why it is worth asking. Immune-modulating ingredients warrant particular care alongside immunosuppressive drugs or with autoimmune conditions. Take the full ingredient list to your vet rather than the marketing copy.
There is no established dose for dogs, which is worth saying plainly. What you can do is compare like with like: a product that states a beta-glucan percentage can be evaluated against another that does. A product that states only "polysaccharides", or nothing, cannot be compared to anything.
Not sure it is right for your pet?
Our eligibility screener checks your animal's medications and conditions against every ingredient on the formulation sheet. One minute, eight questions, and it will tell you if we are not a fit.