title: Dose-dependent suppression of serum cholesterol by tocotrienol-rich fraction (TRF25) of rice bran in hypercholesterolemic humans.
abstract: Tocotrienols are effective in lowering serum total and LDL-cholesterol levels by inhibiting the hepatic enzymic activity of beta-hydroxy-beta-methylglutaryl coenzymeA (HMG-CoA) reductase through the post-transcriptional mechanism. alpha-Tocopherol, however, has an opposite effect (induces) on this enzyme activity. Since tocotrienols are also converted to tocopherols in vivo, it is necessary not to exceed a certain dose, as this would be counter-productive. The present study demonstrates the effects of various doses of a tocotrienol-rich fraction (TRF25) of stabilized and heated rice bran in hypercholesterolemic human subjects on serum lipid parameters. Ninety (18/group) hypercholesterolemic human subjects participated in this study, which comprised three phases of 35 days each. The subjects were initially placed on the American Heart Association (AHA) Step-1 diet and the effects noted. They were then administered 25, 50, 100, and 200 mg/day of TRF25 while on the restricted (AHA) diet. The results show that a dose of 100 mg/day of TRF25 produce maximum decreases of 20, 25, 14 (P<0.05) and 12%, respectively, in serum total cholesterol, LDL-cholesterol, apolipoprotein B and triglycerides compared with the baseline values, suggesting that a dose of 100 mg/day TRF25 plus AHA Step-1 diet may be the optimal dose for controlling the risk of coronary heart disease in hypercholesterolemic human subjects.
authors.affiliation: Advanced Medical Research, 8251 Raymond Road, Madison, WI 53719, USA. nqureshi@mhub.facstaff.wisc.edu
authors.forename: Asaf A
authors.initials: AA
authors.lastname: Qureshi
authors.forename: Saeed A
authors.initials: SA
authors.lastname: Sami
authors.forename: Winston A
authors.initials: WA
authors.lastname: Salser
authors.forename: Farooq A
authors.initials: FA
authors.lastname: Khan
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000008:administration & dosage / Q000627:therapeutic use*; D016632:Apolipoprotein A-I / Q000097:blood; D001055:Apolipoproteins B / Q000097:blood; D002784:Cholesterol / Q000097:blood*; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D003327:Coronary Disease / Q000517:prevention & control; D004305:Dose-Response Relationship, Drug; D005260:Female; D006358:Hot Temperature; D006801:Humans; D006937:Hypercholesterolemia / Q000178:diet therapy / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D012275:Oryza; D010936:Plant Extracts / Q000008:administration & dosage / Q000627:therapeutic use*; D024508:Tocotrienols / Q000008:administration & dosage / Q000627:therapeutic use*; D014280:Triglycerides / Q000097:blood
chemical_list: D000975:Antioxidants; D016632:Apolipoprotein A-I; D001055:Apolipoproteins B; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D010936:Plant Extracts; D024508:Tocotrienols; D014280:Triglycerides; D002784:Cholesterol