Effect of dietary cholesterol, trans and saturated fatty acids on serum lipoproteins in non-human primates

Nine cynomolgus monkeys were rotated randomly through four dietary treatments with each treatment lasting 6 weeks. A wash-out period of 4 weeks was maintained between each dietary rotation. The animals were fed diets containing 32% energy fat derived from palm olein (POL), lauric-myristic-rich oil blend (LM), American Heart Association (AHA) rich oil blend and hydrogenated soybean oil blend (trans). Diets were fed with (phase 1) or without (phase 2) the addition of dietary cholesterol (0.1%). In phase 1, when animals were fed without dietary cholesterol, plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) was significantly raised and high-density lipoprotein cholesterol (HDL-C) was significantly depressed by the trans diets relative to all other dietary treatments. The resulting LDL-C/HDL-C ratio was also significantly increased. The LM diet increased TC significantly relative to the AHA diet while LDL-C was significantly increased compared to both POL and AHA. Apolipoprotein (apo) B was not affected significantly by these dietary treatments. Apo A1 was significantly increased by POL relative to all other dietary treatments. The trans diet reduced apo A1 and the resulting apo B/A1 ratio was increased significantly by trans relative to all other dietary treatments. Addition of 0.1% dietary cholesterol to these diets almost doubled the plasma TC and LDL-C in all dietary treatments. However, HDL-C was only marginally higher with the addition of dietary cholesterol. The LM + C (cholesterol added) diet resulted in the highest TC and LDL-C that was significant compared to all other dietary treatments. Trans + C increased TC compared to POL + C and AHA + C diets while increases in the LDL-C did not attain significance. The addition of dietary cholesterol did not affect HDL-C between treatments whereas plasma triglycerides were significantly increased by the trans + C diet relative to all other treatments. Both the trans + C and LM + C diets increased apo B and decreased apo A1 relative to the POL + C and AHA + C diets. The resulting apo B/A1 ratio was similarly altered. These results affirm that the lauric + myristic acid combination, along with trans fatty acids, increased lipoprotein-associated coronary heart disease risk factors compared to either POL or AHA.