Dose-dependent suppression of serum cholesterol by tocotrienol-rich fraction (TRF 25) of rice bran in hypercholesterolemic humans

• Published in: Atherosclerosis Vol. 161; no. 1; pp. 199 - 207
• Main Authors: Qureshi, Asaf A, Sami, Saeed A, Salser, Winston A, Khan, Farooq A
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ireland Ltd 01.03.2002; Elsevier
• Subjects: Adult; Antioxidants - administration & dosage; Antioxidants - therapeutic use; Apolipoprotein A-I - blood; Apolipoproteins B - blood; Biological and medical sciences; Cholesterol - blood; Cholesterol, HDL - blood; Cholesterol, LDL - blood; Coronary Disease - prevention & control; Disorders of blood lipids. Hyperlipoproteinemia; Dose-Response Relationship, Drug; Female; HDL-cholesterol; Hot Temperature; Humans; Hypercholesterolemia - diet therapy; Hypercholesterolemia - drug therapy; Hypercholesterolemic human subjects; LDL-cholesterol; Lipid parameters; Male; Medical sciences; Metabolic diseases; Middle Aged; Novel tocotrienols (TRF 25); Oryza; Plant Extracts - administration & dosage; Plant Extracts - therapeutic use; Tocotrienols - administration & dosage; Tocotrienols - therapeutic use; Total cholesterol; Triglycerides - blood; Hypercholesterolemic human subjects; HDL-cholesterol; HDL-cholesterol, high density lipoprotein cholesterol; apo A1, apolipoprotein A1; AHA, American Heart Association; HPLC, high performance liquid chromatography; LDL-cholesterol; Novel tocotrienols (TRF 25); HMG-CoA, β-hydroxy-β-methylglutaryl coenzymeA; apo B, apolipoprotein B; Total cholesterol; Lipid parameters; LDL-cholesterol, low density lipoprotein cholesterol; TRF 25, tocotrienol-rich fraction of stabilized and heated rice bran; Human; Hypercholesterolemia; Diet therapy; Metabolic diseases; Lipids; Serum; Hyperlipoproteinemia; Supplemented diet; Dyslipemia; Cholesterol; Rice bran
• ISSN: 0021-9150; 1879-1484
• DOI: 10.1016/S0021-9150(01)00619-0

Tocotrienols are effective in lowering serum total and LDL-cholesterol levels by inhibiting the hepatic enzymic activity of β-hydroxy-β-methylglutaryl coenzymeA (HMG-CoA) reductase through the post-transcriptional mechanism. α-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 (TRF 25) 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 TRF 25 while on the restricted (AHA) diet. The results show that a dose of 100 mg/day of TRF 25 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 TRF 25 plus AHA Step-1 diet may be the optimal dose for controlling the risk of coronary heart disease in hypercholesterolemic human subjects.