Effect of dietary supplementation with alpha-tocopherol on the oxidative modification of low density lipoprotein.
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 less than 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.2+_
Jialal
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Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas 75235-9052.
Grundy
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SM
D000284:Administration, Oral; D000328:Adult; D002338:Carotenoids / Q000097:blood; D006801:Humans; D007700:Kinetics; D008077:Lipoproteins, LDL / Q000097:blood / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction / Q000187:drug effects; D010919:Placebos; D016037:Single-Blind Method; D013858:Thiobarbiturates / Q000097:blood; D014810:Vitamin E / Q000008:administration & dosage*; D019207:beta Carotene
D008077:Lipoproteins, LDL; D010919:Placebos; D013858:Thiobarbiturates; D019207:beta Carotene; D014810:Vitamin E; D002338:Carotenoids; C029684:thiobarbituric acid