Elevated circulating lipid levels are known risk factors for cardiovascular diseases (CVD). In order to examine the effects of quercetin on hepatic lipid metabolism and detailed serum lipid profiles, mice received a mild-high-fat diet without (control) or with supplementation of 0.33% (w/w) quercetin for 12 weeks. Gas chromatography and 1H nuclear magnetic resonance were used to measure quantitatively serum lipid profiles and whole genome microarray analysis was used to identify the responsible mechanisms in liver. There were no significant differences found in mean body weight, energy intake and hepatic lipid accumulation between the quercetin and control group. In serum of quercetin-fed mice, TG levels were decreased with 15%, poly unsaturated fatty acids (PUFA) were increased with 14% and saturated fatty acids were decreased. Palmitic acid, oleic acid, and linoleic acid were all decreased in quercetin-fed mice by 9-15%. Both palmitic acid and oleic acid can be oxidized by omega-oxidation. Indeed, gene expression profiling showed that quercetin increased hepatic lipid metabolism, especially omega-oxidation. At the gene level, this was reflected by the up regulation of cytochrome P450 (Cyp) 4a10, Cyp4a14, Cyp4a31 and Acyl-CoA thioesterase 3 (Acot3). Two relevant regulators, Cytochrome P450 oxidoreductase (Por, rate limiting for cytochrome P450s) and the transcription factor Constitutive androstane receptor (Car; official symbol Nr1i3) were also up regulated in the quercetin-fed mice. We conclude that quercetin intake increased hepatic lipid omega-oxidation and lowered corresponding circulating lipid levels, a process that may involve Por and Car, and results in a potential beneficial CVD preventive effect.
- human nutrition and health