Dose-dependent suppression of serum cholesterol by tocotrienol-rich fraction (TRF25) of rice bran in hypercholesterolemic humans

Atherosclerosis. 2002 Mar;161(1):199-207. doi: 10.1016/s0021-9150(01)00619-0.

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.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antioxidants / administration & dosage
  • Antioxidants / therapeutic use*
  • Apolipoprotein A-I / blood
  • Apolipoproteins B / blood
  • Cholesterol / blood*
  • Cholesterol, HDL / blood
  • Cholesterol, LDL / blood
  • Coronary Disease / prevention & control
  • Dose-Response Relationship, Drug
  • Female
  • Hot Temperature
  • Humans
  • Hypercholesterolemia / diet therapy
  • Hypercholesterolemia / drug therapy*
  • Male
  • Middle Aged
  • Oryza*
  • Plant Extracts / administration & dosage
  • Plant Extracts / therapeutic use*
  • Tocotrienols / administration & dosage
  • Tocotrienols / therapeutic use*
  • Triglycerides / blood

Substances

  • Antioxidants
  • Apolipoprotein A-I
  • Apolipoproteins B
  • Cholesterol, HDL
  • Cholesterol, LDL
  • Plant Extracts
  • Tocotrienols
  • Triglycerides
  • Cholesterol