The science behind functional mushrooms

Functional mushroom websites tend to go one of two ways. One tells you a mushroom has been used for thousands of years and more or less leaves it there. The other gives you a photograph of somebody in a lab coat, a handful of studies and the impression that the matter has been settled.

I do not find either especially satisfying.

Mushrooms are food, decomposers, parasites, symbionts, medicines in traditional systems, poisons, sources of drugs, laboratory organisms and occasionally the thing growing behind the shed that nobody noticed until yesterday. They have histories, names, habitats, chemistry and ways of being used long before anybody gets to a placebo-controlled trial.

That is what I want this library to keep hold of.

The clinical evidence matters, obviously. If somebody says a mushroom improves memory, lowers something, raises something or treats a disease, then eventually you have to ask what happened when people actually took it. But that is only one part of the subject, and I do not want every mushroom page to begin by pretending the organism exists mainly to answer a health claim.

Start with the mushroom

Before asking whether Reishi, Lion’s Mane or Cordyceps “works”, it helps to know what it actually is.

What species is it? What else has carried that name? Where does it grow? What does it grow on? Are we talking about the fruiting body, the mycelium, spores, a fermented culture or one purified compound? Has somebody boiled it, dried it, powdered it, fermented it, extracted it with alcohol or simply fried it in butter?

These are not bits of trivia to get through before the important science begins. They are part of the reason the science can become so confusing.

Reishi is a hard, bitter wood-rotting bracket fungus with a long Chinese cultural history and a taxonomy that has been causing trouble for decades. Lion’s Mane is a protected British fungus, a genuinely good food and a source of the hericenone and erinacine chemistry that helped create its modern brain reputation. Cordyceps starts with a fungus parasitising an insect and then somehow becomes even less straightforward once you discover that the wild caterpillar fungus, Cordyceps militaris, CS-4 and cordycepin are not the same thing.

There is quite a lot to learn before anybody needs a p-value.

Old knowledge belongs here

People were observing and using mushrooms long before PubMed existed. Chinese materia medica, Taoist writing, Japanese food and medicinal traditions, Tibetan medicine, Indian ethnomedicine, Ayurveda where we can actually source it, folklore, cultivation history and ordinary culinary use all belong in the library.

I think the important thing is to let each source be what it is.

A passage in the Bencao Gangmu is a historical source. It can tell us what somebody wrote, classified or used at the time. It does not become a randomised trial because the passage is old and interesting.

The same applies to Ayurveda. If we can identify an actual text, passage, edition, translation and organism with reasonable confidence, then it belongs here. If all we have is a modern website saying a mushroom has been “used in Ayurveda for 5,000 years”, I would rather leave the gap open than turn the sentence into history by repetition.

China creates the same problem in a different form. Historical names such as zhi, houtougu or dong chong xia cao cannot simply be translated into a modern Latin species name and carried backwards through time as though everyone had been doing molecular taxonomy for two thousand years.

None of this makes traditional knowledge less interesting. I think it makes it more interesting, because then you can actually see how different cultures understood the organism instead of forcing everything into a modern clinical argument.

Homeopathy, naturopathy and the other shelves

There is another body of mushroom literature that tends either to get ignored completely or thrown into a big bag labelled “traditional medicine”.

Homeopathy has its own fungal literature. Western herbal medicine has its own literature. Naturopathy has its own literature. They overlap sometimes, but they are not the same thing and there is no reason to pretend they are.

My 2022 fungi dissertation turned out to be a useful starting map for the homeopathic side. I used Frans Vermeulen’s Spectrum Materia Medica Volume 2, Massimo Mangliavori’s Fungi Materia Medica Clinica, Sankaran’s Schema, repertory literature and other fungal materia medica. What struck me then, and still does now, was how small the homeopathic fungal world looked compared with the size of the fungal kingdom.

In the dissertation I quoted Vermeulen’s account of repertories and encyclopaedias containing 72 fungal remedy names, with 32 carrying no symptoms and another 27 having fewer than twenty. His broader fungal materia medica was an attempt to build something much larger from toxicology, mycology, medicinal use, folklore and homeopathic symptoms, while also acknowledging that clinical verification was lacking.

I want to go back to Vermeulen and the other original sources properly rather than rely forever on my own dissertation quoting them, but the historical pattern is already interesting. Lion’s Mane and Reishi were barely represented in the homeopathic material I reviewed, while Cordyceps appeared much more clearly.

That tells us something about what one medical tradition noticed and what it largely ignored. It does not tell us whether a homeopathic preparation works.

Naturopathy needs the same treatment. At the moment my dissertation does not give us an explicitly naturopathic source I am happy to label as such, so that shelf still needs proper work. I would rather spend the time finding the actual naturopathic texts and practitioner literature than quietly relabel a general mushroom book because it would fill the section.

Then there is the chemistry

Fungi are very good chemists.

Penicillin came from fungi. Statins came from fungi. Cyclosporine came from a fungus. Ergot alkaloids, psilocybin, amatoxins and a frankly ridiculous number of other biologically active molecules come from fungi too. So the idea that a mushroom might contain interesting chemistry is hardly controversial.

The harder bit is working out what any particular compound does in a person.

Reishi contains polysaccharides, triterpenoids and a long list of other compounds. Lion’s Mane gave us hericenones from the fruiting body and erinacines from the mycelium. Cordyceps militaris gave us cordycepin. Researchers can isolate these things, expose cells to them, give them to animals and start working out what pathways or mechanisms might be involved.

I like this part of the research because it is often where the story begins. The problem comes when the beginning of the story is sold as the ending.

A compound making a cell produce more nerve growth factor is interesting. It is not the same thing as somebody remembering where they put their keys. A mouse changing weight, behaviour or inflammatory markers is useful information about that model. It is not automatically a human outcome.

We keep the laboratory and animal work because throwing it away would be daft. We just do not let it impersonate a clinical trial.

What happens when people take it?

Eventually, if you want to make a claim about people, somebody has to give the material to people and compare what happens.

This is where mushroom research becomes much less romantic.

Human studies are expensive, difficult and full of ways to make an answer look cleaner than it really is. Studies can be tiny. Products differ. Species names change. Outcomes multiply. A paper can find no difference from placebo and still lead with an improvement from baseline inside the treatment group. A subgroup can suddenly become the interesting bit. A pilot study can be cited for fifteen years until it starts to feel much larger than it ever was.

None of that requires bad faith. Research is done by people, and people like interesting results.

Our basic rule is simple enough. If a study has a control group, we care about what happened between the groups. Somebody improving after taking a mushroom is worth recording. Somebody improving more than the placebo group tells us something rather different.

Null results stay in. Negative results stay in. If the paper does not give us enough information to decide, we say so rather than helping it along.

That sounds obvious, but it is amazing how different the mushroom literature looks once you actually enforce it.

The preparation matters, but it is still the mushroom

This is another area where people sometimes disappear into arguments that are technically correct and practically useless.

A hot-water Reishi extract, a glycerin Reishi extract and Reishi powder are not chemically identical. Of course they are not. Neither are mashed potato, chips and a baked potato. They are still all potato.

Preparation matters because it changes what is present and how much of it is available. Water will move some things better than alcohol. Alcohol will move others. A powder contains material that an extract may leave behind. Fermentation changes things again.

That changes how directly one study applies to another product, but it does not turn the ingredient into a completely unrelated object.

Where I become more cautious is when we move between fruiting body, mycelium, spores and purified fractions, or when the species itself changes. A fruiting-body extract and an isolated molecule from a different fungus may both appear under the same commercial story, but they are clearly not the same research material.

So we treat relevance as a gradient. Same mushroom, same part, different preparation is still relevant with a caveat. Move further away in fungal part, species or purification and the caveat gets larger.

I find that much more useful than pretending every study is either identical to the bottle on the shelf or completely worthless.

Reviews can be messy too

Once enough studies exist, somebody writes a systematic review and the whole thing suddenly looks very authoritative.

Sometimes it deserves to.

Sometimes the review is simply a tidy summary of five tiny trials that were not especially convincing to begin with.

A review is only as useful as the studies it found, the question it asked and the way it combined them. The Lion’s Mane literature gives us a good example. One recent review sounds substantial until you notice that twenty of the twenty-three included studies were cell or animal work and only three involved people.

Cordyceps manages a different version of the same problem. Some reviews contain dozens of trials, but the material underneath them may include several different fungi and fermentation products being treated as one category.

We include reviews and meta-analyses because they are useful. We also look at what went into them, because the word “systematic” does not magically improve the studies underneath.

Safety is part of the research

“Natural” does not tell you very much about safety. Death caps are natural too, although I am not suggesting your Reishi bottle is about to kill you.

Clinical trials can record adverse events, but small short trials are poor tools for finding rare problems. Case reports can pick up unusual events, but one case report cannot tell you how often something happens.

This is why the safety sections stay quite literal. One case stays one case. A multi-ingredient product stays multi-ingredient. If a report concerns wild cicada fungus rather than Cordyceps militaris, we do not quietly turn it into a generic Cordyceps warning. If the authors of a liver-injury report blamed another ingredient rather than Lion’s Mane, we do not relabel it because it makes a better headline.

The boring details matter rather a lot here.

Anecdotes are still observations

I do not think anecdote is worthless. Most things humans investigate started with somebody noticing something.

“I ate this and felt different” is information. The difficulty is working out what caused the difference. Expectation, coincidence, natural variation, regression to the mean, whatever else changed that week and the intervention itself can all sit on top of one another.

That is why controlled trials exist, but it does not mean everybody’s personal experience needs to be sneered at until a statistician approves it.

People take Lion’s Mane and say they feel sharper. People take Cordyceps and say they have more energy. Other people take exactly the same thing and notice nothing. Those are all real reports. They are just not a clean way of establishing causation.

I am quite happy to live with both ideas at once. Anecdotes can be worth listening to, and they are not proof.

What we actually publish

Every research page is built around the mushroom rather than around a verdict.

We look at biology and taxonomy, names, ecology, cultivation, food use, historical and traditional sources, chemistry, the history of modern research, laboratory and animal work, human studies, reviews, safety and the things nobody has answered yet.

Underneath the readable page sits the research ledger. That records what we searched, what we found, which papers we actually read, what material was used, what the control was, what happened between groups, what could not be resolved and where the gaps still are.

The software is deliberately boring. I would like it to stay that way.

Its job is to stop us quietly forgetting a null result, changing a species name because the old one is inconvenient, or turning a before-and-after change into a placebo-controlled effect.

Reishi

Reishi is probably the fullest example of what I want this library to become. There is Chinese materia medica, Taoist symbolism, cultivation, spores, fruiting bodies, triterpenes, polysaccharides, decades of laboratory work and 31 verified human primary studies in the current corpus.

There is also a species-identification problem running through almost the whole modern literature, which makes even the apparently simple question “what did they test?” rather more interesting than it should be.

Read the Reishi research.

Lion’s Mane

Lion’s Mane is a completely different mushroom and has ended up with a completely different modern story. It is food, it grows wild in Europe, it is protected in Britain and the brain story grew largely from Japanese chemistry work on hericenones and erinacines rather than from some neat ancient tradition of cognitive use.

The current corpus contains 16 verified human primary studies. Some are positive, many are mixed or null, and the confidence surrounding Lion’s Mane in popular culture is still considerably ahead of the clinical evidence.

Read the Lion’s Mane research.

Cordyceps

Cordyceps is where the material problem becomes impossible to ignore. The famous wild caterpillar fungus, Ophiocordyceps sinensis, has no human trials in our current corpus. The 34 verified human studies are instead about fermentation products, Cordyceps militaris, other Cordyceps taxa or material the papers do not identify well enough for us to place confidently.

That makes the page much more interesting than another list of “Cordyceps benefits”, because the traditional reputation, the modern clinical literature and the chemistry people use to explain the product often belong to different materials.

Read the Cordyceps research.

Where the library goes next

For now, not into another ten mushroom species.

We have enough breadth to prove the idea. What I want next is more depth around the mushrooms already here.

That means going back through Chinese materia medica properly, finding the Tibetan Cordyceps sources we have only reached through secondary literature, checking Japanese and Korean material, separating Indian ethnomedicine from genuine Ayurveda, following the homeopathic fungal literature back to the original materia medicas and provings, finding actual naturopathic sources rather than guessing, and keeping the bits of folklore, food history and cultivation that normally get lost once a mushroom becomes a supplement.

Some of that work will confirm familiar stories. Some will probably kill them.

Both are useful.

There will still be papers we cannot obtain, old texts we cannot confidently map to a modern species and claims we leave unresolved because the source is not good enough. I am fine with that. I would rather have an honest gap in the library than a beautifully sourced-looking sentence that nobody has actually checked.

The point is not to finish mushrooms.

It is to keep finding out what is really there.