Background: Emerging evidence suggested phytosterol esters (PE) exhibited an advantage over naturally occurring phytosterols in reducing atherosclerosis risk factors due to improved fat solubility and compatibility. However, the effects of dietary patterns of PE on lipid-lowering activity were limited and inconsistent. This study aimed to explore the effects of dose and frequency of α-linolenic acid rich phytosterol esters (ALA-PE) on cholesterol and triglyceride metabolism markers focused on intestinal cholesterol absorption and bioconversion of ALA in liver.
Methods: Dose-dependency study Male Syrian golden hamsters were fed high-fat diets (HFD) containing low, medium and high dose of ALA-PE (0.72 %, 2.13 % and 6.39 %) for 6 weeks. The high fat diet contained 89.5 % chow diet, 0.2 % cholesterol, 10 % lard and 0.3 % bile salt. Dose-frequency study Male Syrian golden hamsters were provided: (I) 0.4 mL/100 g peanut oil by gavage once a day; (II) 0.4 mL/100 g ALA-PE by gavage once a day; (III) 0.2 mL/100 g ALA-PE by gavage twice a day; (IV) 0.133 mL/100 g ALA-PE by gavage three times a day; (V) 0.1 mL/100 g ALA-PE by gavage four times a day for 6 weeks with a high-fat diet simultaneously.
Results: ALA-PE dose-dependently lowered plasma total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) concentrations with a maximal decrease of 42 %, 59 % and 73 %, respectively (p < 0.05). Compared to HFD, TC, LDL-C and TG concentrations were significantly lower (p < 0.01) in hamsters consumed HFD plus ALA-PE for 1-4 times per day but there were not remarkable differences among different consumption frequencies. No significant changes in plasma antioxidant capacity and lipid peroxidation levels were observed among HFD and HFD plus different doses of ALA-PE groups. The contents of hepatic α-linolenic (ALA), docosapentaenoic (DPA) and docosahexaenoic (DHA) acids were dose-dependently increased in different ALA-PE groups compared to those in HFD group. The abundance of mRNA for intestinal sterol transporters Niemann-Pick C1-Like 1 (NPC1L1), ATP-binding cassette (ABC) transporters ABCG5 and ABCG8 indicated no significant differences among all groups.
Conclusion: ALA-PE dose-dependently improved lipid profile in hamsters fed HFD independent of intestinal ABCG5, ABCG8 and NPC1L1, accompanying by increased conversion of ALA to DPA and DHA in liver. ALA-PE manifested "once a day" lipid-lowering efficacy, highlighting a promising preventive strategy for metabolic syndrome.