The Effect of Long Chain Saturated Fatty Acids (12 : 0, 14 : 0, 16 : 0, 18 : 0) and Dietary Cholesterol Levels on Plasma and Hepatic Cholesterol Concentrations in the Mongolian Gerbil

In order to independently examine the effects of long-chain saturated fatty acids and dietary cholesterol levels on plasma and hepatic cholesterol concentrations, six different diets were fed to male Mongolian gerbils (14 gerbils pes grcup) for an 8-week period. Purified diets contained 36% energy as fat (each saturated fatty acid tested comprised about 20% of the total fat energy) and 0.06% (w/w) cholesterol, corresponding to typical human consumption patterns in Western diets. Fat blends were formulated with natural fat sources. To determine the effects of different saturated fatty acids on plasma and liver cholesterol levels, four of the six diets contained constant levels of all nutrients except for the amounts of lauric acid (12 0), myristic acid (14 : 0), palmitic acid (16 0), and stearic acid (18 : 0). Dietary cholesterol effects were tested using 16 : 0-enriched diets containing 0, 0.006, and 0.06% (w/w) cholesterol. None of the plasma lipids were influenced by fatty acid treatment, including triglycerides, plasma total-, VLDL+LDL-, and HDL-cholesterol. However, hepatic esterified cholesterol concentrations were increased in the palmitic and stearic arid diet groups compared to the lauric and myristic acid diet group. The molar ratios of hepatic EC/FC were the highest in the palmitic acid diet (12.2 $\pm$0.6) and the lowest in the myristic acid diet (6.4$\pm$0.2). Dietary cholesterol significantly (p<0.001) increased the plasma total cholesterol which was due to the increase of both HDL-and VLDL+LDL-cholesterol. In the absence of dietary cholesterol and compared to other species, the gerbil exhibited a high molar ratio of hepatic EC/FC, which was funker elevated by dietary cholesterol feeding (0.06%). The results from this study indicate that hepatic cholesterol concentrations are sensitive to both low levels of dietary cholesterol and saturated fatty acid chain length and also, that plasma cholesterol concentrations are sensitive to low levels of dietary cholesterol .