Nano-Encapsulated Phytosterols Ameliorate Hypercholesterolemia in Mice via Dual Modulation of Cholesterol Metabolism Pathways.

The limited bioavailability of free phytosterols restricts their clinical application in managing hypercholesterolemia. This study aimed to develop phytosterol nanoparticles (PNs) to enhance bioactivity and investigate their cholesterol-lowering efficacy and underlying mechanisms in vivo. Phytosterol nanoparticles (PNs) (93.35 nm) were engineered using soy protein isolate and administered orally at concentrations of 4.00-12.50 mg/mL to high-fat-diet-induced hypercholesterolemic mice ( = 60) over a 4-week period. Serum and hepatic lipid profiles, histopathology, gene/protein expression related to cholesterol metabolism, and fecal sterol content were evaluated. PNs dose-dependently reduced serum total cholesterol (TC: 28.6-36.8%), triglycerides (TG: 22.4-30.1%), and LDL-C (31.2-39.5%), while increasing HDL-C by 18.7-23.4% compared to hyperlipidemic controls ( < 0.01). Hepatic TC and TG accumulation decreased by 34.2% and 41.7%, respectively, at the highest dose, with histopathology confirming attenuated fatty degeneration. Mechanistically, PNs simultaneously suppressed cholesterol synthesis through downregulating HMGCR (3.2-fold) and SREBP2 (2.8-fold), while enhancing cholesterol catabolism via CYP7A1 upregulation (2.1-fold) at protein level. Although less potent than simvastatin ( < 0.05), the nanoparticles exhibited unique dual-pathway modulation absent in conventional phytosterol formulations. Fecal analysis revealed dose-responsive cholesterol excretion (36.01 vs. 11.79 mg/g in controls), indicating enhanced enteric elimination. While slightly less potent than simvastatin ( < 0.05), PNs offered unique dual-pathway modulation absent in conventional phytosterol formulations. Nano-encapsulation significantly improves the bioavailability and hypocholesterolemic efficacy of phytosterols. PNs represent a promising nutraceutical strategy for cholesterol management by concurrently regulating cholesterol synthesis and catabolism, with potential application in both preventive and therapeutic contexts.