Dietary fat and vitamin E have differential effects on serum lipid levels

The experiment was designed to study the effects of dietary fat and vitamin E on serum lipid status, an important indicator of risk for atherosclerosis. The influences of dietary fat and d,1-α-tocopheryl acetate (vitamin E) on serum fatty acid profiles, total cholesterol, HDL-cholesterol, LDL-cholesterol and triglyceride concentrations were studied in 40 weanling male Sprague-Dawley rats. Rats were fed semipurified diets containing corn oil or lard and graded levels (0, 100, 5000 or 15000 ppm) of vitamin E for 8 weeks. Serum vitamin E level was significantly greater in the corn oil group with 100 ppm vitamin E than in the lard group with 100 ppm vitamin E (p<0.05). Lipid status was verified by serum fatty acid profiles. Serum C18:0 (stearic acid) and C18:1 n-9 (oleic acid) of rats were significantly greater in the lard groups than in the corn oil groups with an equal amount of vitamin E except with the 100 ppm vitamin E, serum C18:2 n-6 (linoleic acid) of rats was significantly greater in the corn oil groups than in the lard groups with an equal amount of vitamin E, and C20:4 n-6 (arachidonic acid) of rats was significantly greater in the corn oil group with 15000 ppm vitamin E than in the lard group with 15000 ppm vitamin E (p<0.05). Rats fed corn oil had significantly greater serum HDL-cholesterol than rats fed lard with 100 or 15000 ppm vitamin E (p<0.05). However, serum LDL-cholesterol level was significantly greater in the rats fed corn oil with 100 ppm vitamin E compared with that in the rats fed lard with 100 ppm vitamin E (p<0.05). Both dietary fat and vitamin E had effects on serum HDL-cholesterol, however, no interaction existed between dietary fat and vitamin E on serum HDL-cholesterol. With regard to serum LDL-cholesterol, only vitamin E had a significant effect. The results suggested that both dietary fat and vitamin E can influence atherosclerosis progression via their effects on serum lipid status, but no interaction between them on serum lipid status was found.