The effect of α-tocopherol supplementation on LDL oxidation: A dose-response study

Ishwarlal Jialal, Cindy J. Fuller, Beverley A. Huet

Research output: Contribution to journalArticle

325 Scopus citations

Abstract

Because much data have accrued to support the concept that oxidatively modified LDL (Ox-LDL) can promote atherogenesis, the role of antioxidants in decreasing LDL oxidation has assumed great importance. High-dose α-tocopherol supplementation in humans decreases the susceptibility of LDL to oxidation. Hence, the aim of the present study was to ascertain the minimum dose of α-tocopherol that would decrease the susceptibility of LDL to oxidation. The effect of α-tocopherol in doses of 60, 200, 400, 800, and 1200 IU/d on copper-catalyzed LDL oxidation was tested in a randomized placebo-controlled study over 8 weeks. There were eight subjects in each group. Oxidation of LDL was monitored by measuring the formation of conjugated dienes and lipid peroxides by the thiobarbituric acid-reacting substances (TBARS) assay over an 8-hour time course at baseline and after 8 weeks of supplementation. Neither placebo nor any of the doses of α-tocopherol resulted in any side effects or exerted an adverse effect on the plasma lipoprotein profile. However, there was a dose-dependent increase in plasma and lipid-standardized α-tocopherol levels with increasing doses of α-tocopherol supplementation. LDL α-tocopherol appeared to follow a similar trend. When the time-course curves of LDL oxidation and the kinetics of LDL oxidation were examined, there was no significant effect at 8 weeks compared with baseline in the groups that received placebo or α-tocopherol 60 or 200 IU/d. However, in the groups that received at least 400 IU/d α-tocopherol, there was a decreased susceptibility of LDL to oxidation, as shown by the mean levels in the time-course curves, prolongation in the lag phase, and a decrease in the oxidation rate. Furthermore, both plasma and LDL α-tocopherol correlated significantly with the lag phase of oxidation and inversely with the oxidation rate. The results of the present study show that the minimum dose of α-tocopherol needed to significantly decrease the susceptibility of LDL to oxidation is 400 IU/d.

Original languageEnglish (US)
Pages (from-to)190-198
Number of pages9
JournalArteriosclerosis, thrombosis, and vascular biology
Volume15
Issue number2
DOIs
StatePublished - Feb 1995

Keywords

  • Antioxidants
  • Atherosclerosis
  • LDL oxidation
  • Lipid peroxidation
  • α-tocopherol

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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