The hypolipidaemic effects of plant sterols are well established. However, mechanisms by which plant sterols lower plasma cholesterol levels, particularly at the molecular level, have not been clearly elucidated. The objective of the present study was to determine whether different plant sterol analogues reduce plasma cholesterol levels by up regulating the sterol transporters ABCG5 and ABCG8 in the liver and/or small intestine. Male Golden Syrian hamsters were divided into eight groups. Groups 1 and 2 were fed a maize starch–casein–sucrose-based diet that did not contain cholesterol (control; Con) or the Con diet with the addition of 0·25 % cholesterol (Ch-Con). Groups 3–8 were fed the Ch-Con diet supplemented with 1 % plant sterols, 1 % plant stanols, 1 % of a plant sterol and stanol mixture (50:50), 1·76 % plant sterol–fish oil esters, or 0·71 or 1·43 % stanol–ascorbic acid esters, respectively. After 5 weeks, the Ch-Con diet up regulated the ABCG5 mRNA expression and tended (P = 0·083) to increase ABCG8 mRNA expression in the liver, but did not affect both genes’ expression in the small intestine compared with the Con diet. Hamsters fed 0·7 % stanol esters showed lower plasma cholesterol levels (P < 0·001) and also lower liver ABCG5 mRNA expression (P < 0·05) compared with the Ch-Con diet. Plant stanols, stanol esters, and sterol esters did not affect the ABCG5 or ABCG8 mRNA expressions in the liver and intestine although they reduced plasma cholesterol levels. These results suggest that plant sterols and their derivatives reduce plasma cholesterol levels independently from the mRNA expression of ABCG5 and ABCG8 transporters.
Lipid-lowering Activity of Natural and Semi-Synthetic Sterols and Stanols
