A dose response comparison of the effect of natural and synthetic alpha-tocopherol on LDL oxidation

Much data support a proatherogenic role for oxidized LDL (ox-LDL). It has previously been shown that alphatocopherol (AT) can decrease the oxidative susceptibility of LDL. In this study, we tested in a dose response fashion the effect of natural (n-AT) and synthetic (s-AT) on copper-catalyzed LDL oxidation. This was a placebo controlled, randomized study in which the volunteers received either a placebo, n-AT or s-AT at doses of 100, 200, 400 and 800 international units (IU)/day. The total number of volunteers studied was 85. Copper-catalyzed LDL oxidation was monitored at baseline and following two months of AT supplementation by measurement of conjugated dienes and lipid peroxides over an 8 hour time course. Both n-AT and s-AT resulted in equivalent dose dependent enrichment in plasma and LDL AT levels. Both n-AT and s-AT significantly prolonged the lag phase at doses of 400 and 800 IU/day. There were no significant differences in plasma and LDL AT levels and LDL oxidation between synthetic and natural AT at any dose in IU or per mg AT ingested. In conclusion, both natural and synthetic alpha-tocopherol resulted in similar enrichment in LDL alpha-tocopherol levels and decreases in LDL oxidative susceptibility.