Digestive characteristics and cholesterol-lowering effects of phytosterols-loaded nanostructured lipid carriers: Role of guar gum-based polysaccharide coatings

The digestive characteristics and in vitro cholesterol-lowering activity of phytosterols-loaded nanostructured lipid carrier (PS-NLC) modified with four guar gum variants (GG, CGG, PHGG, and PHCG) were studied to evaluate the potential of these complexes as functional food ingredients. Simulated digestion results indicated that while none of the polysaccharides significantly affected the final digestion extent of the lipid carriers, GG, CGG, and PHCG reduced the initial digestion rates. The in vitro cholesterol-lowering activity followed the order: GG-PS-NLC > CGG-PS-NLC > PHCG-PS-NLC > PHGG-PS-NLC, with activities corresponding to 1.91, 1.76, 1.55, and 1.25 times that of PS-NLC, respectively. Analysis of the in vitro cholesterol-lowering mechanism revealed that CGG and PHCG, benefiting from their positive charge, exhibited superior cholesterol micelle binding and cholesterol binding capabilities; GG extensively captured bile salts via hydrogen bonds due to its large molecular weight and high viscosity. These findings indicate that charge and molecular weight are critical factors determining the ability of polysaccharides to assist PS-NLC in lowering cholesterol. The results provide valuable insights for developing NLC multicomponent systems with polysaccharides to deliver phytosterols from food matrices to the digestive environment and apply them in functional foods.