Oxysterols in the Austrian diet

Research project P 13757 Oxysterols Franz ULBERTH 28.06.1999 Sterols like other unsaturated substances are vulnerable to oxidative modifications. The resulting substances are most commonly termed oxysterols (OS). It is a well understood fact, underpinned by several in vitro as well as in vivo experiments, that oxidation products derived from cholesterol (cholesterol oxidation products, COPs) exert negative biological effects. They are reported to be cytotoxic and implicated in atherogenesis, mutagenesis, carcinogenesis, change in cellular membrane properties and inhibition of enzym activities. While data regarding COPs are abundant, knowledge, about oxidation products of phytosterols, another major group of sterols in the human diet, is scarce. By analogy, conditions favouring the formation of COPs should also lead to phytosterol oxidation products (POPs). Due to the structural similarity of cholesterol and phytosterols, their oxidation products should also be similar. Virtually no information exists detailing their biological effects, nor are analytical aspects, formation kinetics, and levels of POPs in foodstuffs adequately documented. The research proposed focuses on an in-depth characterization of chromatographic and spectroscopic properties of POPs. On the basis of these data a reliable and sensitive method for the quantitative determination of OS in complex foodstuffs containing cholesterol as well as phytosterols will be developed. It is anticipated that capillary gas-liquid chromatography coupled to mass spectrometry has the greatest potential of delivering the results envisaged. Another facet of analytical development is the substitution of volatile solvents applied to isolate OS by supercritical carbon dioxide. Finally, dietary intake of OS in Austria will be estimated by analysing ready-to-eat meals from hospital and university canteens, processed foodstuffs (deep-frozen convenience food) and staple food (dairy products, meat products and bakery goods.) A databank holding relevant information about the occurrence of OS should facilitate a sound assessment of risk related to dietary intake of OS.