Brassicasterol is a sterol found in certain plants and other foods such as seafood. Brassicaterol is found in high concentrations in brassica, also known as rapeseed oil. I am not aware of human trials examining the health benefit of brassicasterol when given as a supplement by itself, but it would make sense that brassicaterol would have similar physiological effects as other sterols such as sitosterol and stigmasterol.

Examples of phytosterols
There are a number of phytosterols including beta sitosterol often used by those with prostate issues, stigmasterol, campesterol, and brassicasterol. Certain herbs have a high concentration of phytosterols, for instance, saw palmetto. Plants are not the only ones that contain sterols. Many fish and crustaceans also have a good amount of sterols. For instance, molluscs, such as oysters, contain a number of different sterols with cholesterol present as the major sterol. trans-22-Dehydrocholesterol, brassicasterol, 24-methylenecholesterol, and campesterol.

Brassicasterol in wild coriander leaves
Eryngium foetidum is a Caribbean plant used in folk medicine for the treatment of several antiinflammatory disorders. The extract is rich in terpenic compounds alpha-cholesterol, brassicasterol, campesterol, stigmasterol (as the main component, 95%) clerosterol, beta-sitosterol, delta 5-avenasterol, delta (5)24-stigmastadienol and delta 7-avenasterol.

Brassicasterol in Snails and Slugs
Snails and slugs belong to the phylum Mollusca. The sterols of slugs include eight different sterols: cholesterol is 76-85% of the total sterols, brassicasterol accounts for 4-13%; other sterols identified are lathosterol, 24-methylene cholesterol, campesterol, stigmasterol, sitosterol and sitostanol. In contrast, snails contain two additional sterols, desmosterol and cholestanol. Of the polyunsaturated fatty acids in slugs, linoleic (18:2n-6) and arachidonic acids (20:4n-6) are the major n-6 fatty acids, while linolenic (18:3n-3) and eicosapentaenoic acids (20:5n-3) are the predominant n-3 fatty acids. Docosahexaenoic acid (22:6n-3), the end product in the n-3 fatty acid synthetic pathway and an important membrane fatty acid of mammals, fish and birds, is absent in both slugs and snails.

Brassicasterol in Fungi
Two groups of fungi isolated from human skin and nail are the dermatophytes Epidermophyton, Microsporum and Trichophyton species and the non-dermatophytes Hendersonula toruloidea and Scytalidium hyalinum. Examination of the sterol composition of these fungi by gas chromatography-mass spectrometry has identified five new sterols from dermatophytes, namely cholesterol, campesterol, episterol, fecosterol and sitosterol. These sterols, with ergosterol and brassicasterol, were also identified from extracts of H. toruloidea and S. hyalinum.

Mussel versus Flaxseed Oil and Tuna Oil
A comparison between the composition of the oil derived from the New Zealand Green Lipped Mussel (Lyprinol) and two other oils rich in omega 3 fatty acids, namely flaxseed oil and tuna oil. The main lipid classes in Lyprinol are sterol esters, triglycerides, free fatty acids, sterols and phospholipids while triglycerides are the main lipids in the other two oils. The main omega 3 fatty acids in Lyprinol is EPA and DHA, while in flaxseed oil and tuna oil the main omega 3 fatty acids are ALA and DHA, respectively. The main sterols in Lyprinol are cholesterol and desmosterol / brassicasterol, while in flaxseed oil and tuna oil the main sterols are beta-sitosterol and cholesterol, respectively.

For testing
Acta Psychiatr Scand. 2011. The plant sterol brassicasterol as additional CSF biomarker in Alzheimer's disease. Plant sterols (sitosterol, campesterol, stigmasterol and brassicasterol) are solely dietary-derivable sterols that are structurally very similar to cholesterol. In contrast to peripheral cholesterol, plant sterols can cross the blood-brain barrier and accumulate within mammalian brain. As an impaired function of the cerebrospinal fluid (CSF)-blood barrier is linked to neurodegenerative disorders, i.e. Alzheimer's disease (AD), we investigated whether this results in altered plant sterol concentrations in CSF. Brassicasterol might be a relevant additional biomarker in AD.