Phytosterol-mediated inhibition of intestinal cholesterol absorption is independent of ATP-binding cassette transporter A1.

An increased activity of ATP-binding cassette transporter (ABC) A1 has been proposed as a mechanism underlying the hypocholesterolaemic effect of phytosterols. In the present study, ABCA1-deficient mice (ABCA1-/- mice) were used to examine the involvement of the ABCA1 in the reduction of intestinal cholesterol absorption in response to a phytosterol-enriched diet. A decrease in intestinal cholesterol absorption of 39 and 35 % was observed after phytosterol treatment in ABCA1+/+ mice and in ABCA1-/- mice, respectively. No statistically significant changes in plasma lipoprotein profile or in intestinal ABCG5, ABCG8 and Niemann-Pick C1-Like 1 gene expression levels were found when phytosterol-treated ABCA1-/- mice and untreated ABCA1-/- mice were compared. We conclude that phytosterol inhibition of cholesterol absorption in mice is independent of ABCA1.