Key takeaways
- Mushrooms are mostly water; their dry matter is largely cell-wall carbohydrate.
- Key compound groups include polysaccharides, triterpenes, sterols and ergothioneine.
- Evidence ranges from lab and animal studies to human trials and reviews.
- Most mushroom research is lab or animal work; human evidence is more limited.
- Always ask what kind of study it was and what exactly was tested.
Mushroom science can seem daunting: long compound names, conflicting headlines and studies that appear to say opposite things. This beginner’s guide gives you the basics: what mushrooms are made of, the main groups of compounds researchers study, why the cell wall matters, and how to think about the evidence.
What is a mushroom made of?
Fresh mushrooms are mostly water, typically around 90% of their weight. Their dry matter is largely carbohydrate, especially the fibre-like polysaccharides of the cell wall, with a substantial share of protein, small amounts of fat, and minerals such as potassium. Mushrooms also provide B vitamins, and those exposed to ultraviolet light contain vitamin D. Woody bracket fungi such as Reishi are much drier and more fibrous than soft culinary mushrooms.
The main compound groups
- Polysaccharides, especially beta-glucans, found in the cell wall. See Polysaccharides and What Are Beta-Glucans?
- Triterpenes, prominent in Reishi and chaga. See Triterpenes.
- Sterols, such as ergosterol, the fungal equivalent of cholesterol. See Fungal Sterols.
- Ergothioneine, an unusual sulphur-containing compound. See Ergothioneine.
- Nucleosides, such as cordycepin in Cordyceps militaris. See Cordycepin.
- Species-specific compounds, such as hericenones and erinacines in Lion’s Mane. See Lion’s Mane Compounds.
- Pigments, such as the melanins in chaga and carotenoids in Cordyceps.
Solubility: the key to extraction
These compound groups divide roughly into two camps. Polysaccharides, ergothioneine and nucleosides dissolve in water. Triterpenes, sterols and many pigments dissolve in alcohol. That simple split explains why mushrooms are often extracted in both, and why a product’s extraction method shapes what it contains. See How Solvent Choice Changes What Is Extracted.
Why the cell wall matters
The fungal cell wall, built from chitin and polysaccharides, is tough and hard to digest. It shapes how mushrooms are processed, and why extraction is so important. See The Complete Guide to Mushroom Extraction.
Why the same mushroom can differ
Two samples of the “same” mushroom can differ chemically because of the strain, the substrate it grew on, growing conditions, the age at harvest, the part used, drying and storage. That natural variation is one reason research results can be hard to compare, and why testing matters.
Types of evidence
- In vitro (laboratory) studies test compounds on cells.
- Animal studies test them in living organisms, usually rodents.
- Human studies range from case reports and observational studies to small pilot studies and randomised controlled trials.
- Systematic reviews bring studies together.
Each has its place, but only human evidence can tell us what happens in people. See In Vitro, Animal and Human Studies.
Reading research sensibly
- What kind of study is it?
- What exactly was tested: which species, part and preparation?
- How big was it, and how long did it run?
- Was there a placebo or control group?
- Has it been repeated?
Our research literacy series goes further: How to Read Mushroom Research, How to Judge the Quality of a Mushroom Study and Correlation, Mechanism and Causation. For the research on individual mushrooms, see Lion’s Mane, Reishi, Cordyceps, Chaga and Oyster.
Why we don’t make health claims
Health claims on food supplements are strictly regulated in the UK: only claims that have been scientifically assessed and authorised can be used, and none have been authorised for these mushrooms. The evidence for most mushroom compounds in people is still developing. We explain what our products are and how they’re made, and leave the science to speak carefully for itself.