Although comparative studies of the cholesterolemic properties of
trans fatty acids relative to cis-unsaturates and saturates have been conducted in humans and animals, there is no recent information relating these
lipid responses to susceptibility to
atherosclerosis. Therefore, hamsters were fed diets containing equivalent amounts of
cholesterol (0.12% wt/wt) and test
fats (20% wt/wt) for 8 weeks. Each test fat contained between 50-52% of the-total
triacylglycerols as a single
fatty acid, i.e., 8:0, 14:0, 18:0, cis-18:1, or trans-18:1 while the balance consisted of 16:0, cis-18:1 and 18:2 that were the same for all groups. Plasma total
cholesterol (TC),
low density lipoprotein cholesterol (
LDL-C), and
high density lipoprotein cholesterol (HDL-C) levels were not different for 8:0, cis-18:1, and trans-18:1, whereas 14:0 caused a significant rise in plasma TC,
LDL-C, and HDL-C.
LDL oxidation measurements showed that the lag phase of conjugated diene formation was longest for the trans-18:1 and cis-18:1 groups while rate of conjugated diene formation was lowest for the trans-18:1 and cis-18:1 groups. The trans-18:1- and cis-18:1-fed animals had significantly higher levels of
LDL alpha-tocopherol relative to the 8:0- and 14:0-fed animals. Aortic fatty streak formation was highest for the 14:0- and 8:0-fed animals and lowest for the trans-18:1. In conclusion, the plasma
lipid and
antioxidant properties of trans-18:1 and cis-18:1 were comparable while the trans-18:1-fed hamsters had the least amount of early
atherosclerosis. In addition, 8:0-fed animals unexpectedly had early
atherosclerosis formation similar to the 14:0-fed animals.