Key takeaways
- Sterols stabilise cell membranes; fungi use mainly ergosterol.
- Ergosterol converts to vitamin D2 under UV light.
- Sterols are related to triterpenes.
- They dissolve in alcohol, not water.
Sterols are a small but characteristic part of mushroom chemistry. This article explains fungal sterols, especially ergosterol.
What are sterols?
Sterols are a group of molecules built on a four-ring structure. They help keep cell membranes stable. Animals use cholesterol; plants use phytosterols; fungi use mainly ergosterol.
Ergosterol
Ergosterol is the main sterol in most fungi, including functional mushrooms. It is so characteristic of fungi that it is used in research as a marker of fungal presence.
Ergosterol and vitamin D
When exposed to ultraviolet light, ergosterol converts to vitamin D2. This is why some mushrooms are deliberately exposed to UV light to increase their vitamin D content.
Related compounds
Sterols are chemically related to triterpenes, which share a similar origin. Mushrooms such as Reishi and chaga contain both.
Extraction
Sterols are not water-soluble. They dissolve in alcohol and fats, so they are captured by the alcohol stage of a dual extract.
