The effect of alpha-tocopherol supplementation on LDL oxidation. A dose-response study.
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 alpha-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 alpha-tocopherol that would decrease the susceptibility of LDL to oxidation. The effect of alpha-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 alpha-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 alpha-tocopherol levels with increasing doses of alpha-tocopherol supplementation. LDL alpha-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 alpha-tocopherol 60 or 200 IU/d.(ABSTRACT TRUNCATED AT 250 WORDS)
Jialal
I
I
Center for Human Nutrition, UT Southwestern Medical Center, Dallas 75235-9052, USA.
Fuller
C J
CJ
Huet
B A
BA
D000328:Adult; D000975:Antioxidants / Q000008:administration & dosage* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005227:Fatty Acids / Q000097:blood; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008297:Male; D010084:Oxidation-Reduction / Q000187:drug effects; D014810:Vitamin E / Q000008:administration & dosage* / Q000494:pharmacology
D000975:Antioxidants; D005227:Fatty Acids; D008077:Lipoproteins, LDL; D014810:Vitamin E