Enhanced hypocholesterolemic effects of interesterified oils are mediated by upregulating LDL receptor and cholesterol 7-α- hydroxylase gene expression in rats.

The concentration of LDL cholesterol in plasma is strongly influenced by the amount and type of lipid in the diet. Our studies have shown that positional changes in the fatty acids in blended oil introduced using lipase-catalyzed interesterification differentially modulate circulating LDL levels in rats compared with those observed in rats given a physical blend of oils. To investigate the molecular basis of these differences, transcriptional profiling of genes involved in cholesterol homeostasis was studied after feeding rats with a semipurified diet containing 10% fat from native oils; coconut oil (CNO), rice bran oil (RBO), or sesame oil (SESO); blended (B); CNO+RBO(B) or CNO+SESO(B) and interesterified oil (I); CNO+RBO(I) or CNO+SESO(I) for 60 d. Hepatic LDL receptor (LDL-R) expression significantly increased in rats fed interesterified oils by 100-200% compared with rats fed blended oils and by 400-500% compared with rats fed CNO. Positional alteration in fatty acids of oils used in the diet induced changes in LDL-R expression, which was accompanied by parallel changes in cholesterol-7α-hydroxylase (CYP7A1) and SREBP-2 genes. This suggested that not only the fatty acid type but also its position in the TG of dietary lipids play an important role in maintaining plasma cholesterol levels by suitably modulating gene expression for LDL-R in rat liver.