Effect of dietary supplementation with alpha-tocopherol on the oxidative modification of low density lipoprotein

I. Jialal, S. M. Grundy

Research output: Contribution to journalArticle

251 Scopus citations

Abstract

Much data has accumulated supporting a proatherogenic role for oxidized low density lipoprotein (Ox-LDL). Micronutrient antioxidants such as alpha- tocopherol, the principal lipid-soluble antioxidant, assume potential significance because levels can be manipulated by dietary measures without resulting in side effects. Co-incubation of LDL in vitro with alpha- tocopherol inhibits its oxidative modification. Hence the effect of dietary supplementation with alpha-tocopherol on the time course of copper-catalyzed oxidation of LDL was tested in a randomized placebo-controlled single-blind study. Two groups of 12 male subjects were given either placebo or alpha- tocopherol (800 IU/day) for a period of 12 weeks. Alpha-tocopherol therapy did not result in any side effects or exert an adverse effect on the plasma lipid and lipoprotein profile. While the lipid standardized alpha-tocopherol levels were similar at baseline, the supplemented group had 3.3-fold and 4.4- fold higher levels compared to placebo at 6 and 12 weeks, respectively. In the 15 subjects in whom both plasma and LDL alpha-tocopherol levels were quantitated, there was a significant correlation (r = 0.79, P < 0.0001). At baseline there were no significant differences in the time course curves of thiobarbituric acid-reacting substances (TBARS) activity or conjugated diene formation between the alpha-tocopherol and placebo groups. However, at both 6 and 12 weeks the mean levels of TBARS activity and conjugated diene formation were lower in the alpha-tocopherol group; the most significant differences were manifest at the 3-h time point. Also at both 6 and 12 weeks the mean rate of oxidation was lower in the alpha-tocopherol group. There was a significant inverse correlation between both the 3-h time point and the rate of oxidation with plasma lipid standardized alpha-tocopherol levels. As this study shows that alpha-tocopherol supplementation results in an increase in plasma and LDL alpha-tocopherol levels resulting in a decreased susceptibility of LDL to oxidation, these findings could have major implications in atherosclerosis prevention.

Original languageEnglish (US)
Pages (from-to)899-906
Number of pages8
JournalJournal of Lipid Research
Volume33
Issue number6
StatePublished - 1992
Externally publishedYes

Keywords

  • antioxidants
  • LDL
  • lipid peroxidation
  • modified lipoprotein
  • vitamin E

ASJC Scopus subject areas

  • Endocrinology

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