THE RELATIONSHIP BETWEEN DIETARY PHYTOSTEROLS AND THE STEROLS OF WILD AND CULTIVATED OYSTERS

Wild oysters (C. virginica) contained cholesterol, 24-methylcholesta-5, 22-dienol, 24-methylenecholesterol, 22-dehydrocholesterol, 24-methylcholesterol, 24-ethylcholesterol, 24-norcholesta-5, 22-dienol, 24-ethylcholesta-5, 22-dienol and fucosterol. The same species was cultivated on a defined diet of Thalassiosira pseudonana and Isochrysis sp. The dietary algae were cultured and their sterol compositions were analyzed by gas chromatography and mass spectroscopy. T. pseudonana and Isochrysis sp. had 24-methylenecholesterol and 24-methyl-cholesta-5, 22-dienol as their major sterols. The sterol composition of the cultivated oysters revealed the predominance of cholesterol (19%), 24-methyl-cholesta-5, 22-dienol (21%) and 24-methylenecholesterol (46%). Oysters must be able to bioconvert phytosterols to cholesterol, concentrate dietary cholesterol or synthesize cholesterol de novo.