Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/13/2000
Publication Date: N/A
Interpretive Summary: Because human studies are very expensive and strictly controlled to protect the safety of the subjects, suitable animal models are often used for nutritional or pharmacological studies. One model that is very useful for hypercholesterolemic humans is the genetically hypercholesterolemic pig, which has lipid parameters that are similar to humans. In this study we evaluated the effects of some novel compounds called tocotrienols that are prepared from rice bran on the cholesterol metabolism in these pigs. The diets were supplemented with the tocotrienols for 6 weeks, and blood was collected for analysis. Then the pigs were either sacrificed for analysis of the tissues or transferred to a normal diet for 10 more weeks and then blood was sampled. The tocotrienols caused significant reductions in total cholesterol and low-density-lipoprotein cholesterol, and these effects persisted in the pigs for 10 weeks of a normal diet. This study finds that these products of rice bran can control hereditary high cholesterol.
Technical Abstract: A tocotrienol rich fraction (TRF25) and novel tocotrienols (delta-P21-T3 and delta-P25-T3) of rice bran significantly lowered serum total cholesterol and LDL-cholesterol levels in chickens. The present study evaluated the effects of novel tocotrienols on lipid parameters in swine expressing hereditary hypercholesterolemia. Fifteen 4-month-old genetically yhypercholesterolemic swine were divided into five groups (n=3). Four group were fed the corn-soybean control diet, supplemented with 50 ppm of either TRF25, gamma-tocotrienol, delta-P21-T3, or delta-P25-T3 for 6 weeks. Fifth group was fed control diet for 6 weeks, and served as a control. Serum total cholesterol was reduced 32-36%, LDL-cholesterol 34-40%, apoliprotein B 20-28%, triglycerides 13-19%, thromboxane B2 11-18%, platlet factor 4 12-24%, glucose 22-25%, and glucagon 11-17%, in the treatment groups. Serum HDL-cholesterol increased 8-12%, apoliprotein A1 2-4%, and insulin 2-fold as compared to control. Preliminary data indicated that hepatic activity of the 3-hydroxy-3-methylglutaryl coenzymeA reductase decreased 30% in the treatment groups, and cholesterol 7alpha-hydroxylase activity remained unaffected. Cholesterol and fatty acid levels in various tissues decreased in the treatment groups. After feeding the tocotrienol-supplemented diets, two swine in each group were transferred to the control diet for 10 weeks. The lowering effect of tocotrienols in the serum lipid parameters of the four treatment groups persisted 10 weeks after the termination of feeding tocotrienols. This persistent effect may have resulted due to the high levels of tocotrienols in blood of the treatment groups, suggesting that the conversion of tocotrienols to tocopherols may not be as rapid as reported in chickens and humans.