Sterol Oxides in Foodstuffs: A Review

The toxicological significance of oxidized cholesterol has been well documented in numerous studies. This review focuses on the analysis of dietary sterol oxides in the foodstuffs examined to date with particular emphasis on isolation and characterization techniques. Eight common oxidation products of cholesterol have been identified in certain cholesterol-rich foods subjected to oxidative stress during food processing and/or storage. These products include 25-hydroxycholesterol, α or β 5,6-epoxycholesterol, α or β 7-hydroxycholesterol, 7-ketocholesterol, cholesta-3,5-dien-7-one and cholestane-3β, 5α, 6β-triol. A limited number of studies on the biological effects of dietary phytosterol oxides indicate these products may also be of nutritional concern. Four common autoxidation products of β-sitosterol have been identified in edible oils; these include α or β 7-hydroxysitosterol, 7-ketositosterol and setosta-3,5-dien-7-one. Few quantitative data are available on the sterol oxide content of foods. Moreover, studies without apparent precautions against the artifactual formation of sterol oxides may be flawed. Additional research is necessary to adequately identify and quantify the sterol oxides which most likely exist in certain foods.