Conjugated linoleic acid suppresses the secretion of atherogenic lipoproteins from human HepG2 liver cells.

Studies in healthy humans have shown that consumption of conjugated linoleic acid (CLA) significantly reduced very-low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) blood concentrations. We propose that decreased concentrations are due to the inhibition of VLDL production and secretion [measured by apolipoprotein B100 (apoB100)] from the liver. To investigate the effects of a mixture of CLA isomers on VLDL metabolism, HepG2 liver cells were incubated for 24 h with 50 micromol/L of the different fatty acids. Effects of CLA were compared to a saturated fatty acid (palmitic acid), an n-6 fatty acid (linoleic acid) and no treatment (control). HepG2-cell apoB100 levels were measured using Western blotting. ApoB100 secretion was significantly decreased in cells treated with CLA (44%, p<0.005) compared to control cells and those enriched with palmitic acid. Treatment of cells with CLA also decreased intracellular cholesterol levels. Collectively, these results demonstrate that CLA reduces apoB100 production and secretion compared to saturated and polyunsaturated fatty acids, possibly by limiting the availability of free cholesterol (required for apoB100 production). A reduction in apoB100 production in the body would decrease the levels of VLDL and atherogenic LDL and thus reduce the risk of developing cardiovascular disease.