Diet supplementation with beta-carotene improves the serum lipid profile in rats fed a cholesterol-enriched diet

The present study investigated the underlying mechanism associated with the hypocholesterolemic activity of beta-carotene by examining its effects on the serum lipid profile, fecal cholesterol excretion, and gene expression of the major receptors, enzymes, and transporters involved in cholesterol metabolism. Female Fischer rats were divided into three groups and were fed either a control or a hypercholesterolemic diet supplemented or not supplemented with 0.2 % beta-carotene. After 6 weeks of feeding, blood, livers, and feces were collected for analysis, and quantitative real-time polymerase chain reaction (qRT-PCR) was performed. Dietary supplementation with 0.2 % beta-carotene decreased serum total cholesterol, non-HDL cholesterol, the atherogenic index, and hepatic total lipid and cholesterol contents. These changes were accompanied by an increase in the total lipid and cholesterol contents excreted in the feces. The qRT-PCR analyses demonstrated that the hypercholesterolemic diet promoted a decrease in the gene expression of sterol regulatory element-binding protein 2, 3-hydroxy-3-methylglutaryl CoA reductase, and low-density lipoprotein receptor and an increase in the gene expression of peroxisome proliferator-activated receptor α and cholesterol-7a-hydroxylase. The expression of these genes and gene expression of ATP-binding cassette subfamily G transporters 5and 8 were unaffected by beta-carotene supplementation. In conclusion, the decrease in serum cholesterol and the elevation of fecal cholesterol obtained following beta-carotene administration indicate that this substance may decrease cholesterol absorption in the intestine and increase cholesterol excretion into the feces without a direct effect on the expression of cholesterol metabolism genes.