The effects of dietary oxidized phytosterol (OPS) are unknown. We investigated effects of dietary OPS on lipid metabolism in rats. The OPS contained 7-hydroxy forms of the three major phytosterol was prepared. Male Wistar rats (4 weeks) were fed an AIN76 diet (C group), the basal diet plus 0.25% PS (P group), or 0.25% OPS (O group) for 4 weeks. The rats were anesthetized and dissected, and blood and live were collected and analyzed various lipid metabolism parameters. Plasma total cholesterol (TC) and HDL-C levels were similar in C and P groups but tended to be higher or significantly higher in O group. Liver TG level tended to be lower in P group than in C group, but significantly lower in O group. Liver TC level was significantly lower in both P and O groups than in C group. The Δ6 desaturation index in O group was the highest. The enzyme activity of fatty acid synthesis and mRNA expression level of Δ6 desaturase in liver was significantly higher in both P and O groups compared to C group. These results may have led to the above results. The mRNA level of HMGCR was significantly lower in O group than in both C and P groups. The mRNA level of SREBP2 was the same in both C and P groups, but significantly higher in O group. Similar change was observed in mRNA level of ABCA1. Furthermore, mRNA level of CYP27A1 did not change between C and P groups but was significantly higher in O group. These results are associated with the decrease in liver cholesterol level by OPS consumption. Thus, dietary OPS may modulate fatty acid and cholesterol metabolism in liver after absorption from intestine.
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