Vitamin E supplementation in elderly lowers the oxidation rate of linoleic acid in LDL

Oxidation of LDL–linoleic acid (LDL–LA), a major substrate for lipid peroxidation, may be counteracted by the antioxidant vitamin E. In a 3-month randomized double-blind placebo-controlled trial in 83 apparently healthy Dutch elderly, aged 67–85 years, the direct protective effect of 100 IU vitamin E on the rate of oxidized LDL–LA was studied. The oxidation of LDL–LA was measured by its disappearance after a 5-h in vitro Cu-oxidation of LDL isolated from 1 ml plasma. In the vitamin E group, the decrease in oxidized LDL–LA of 10.4% (p<0.05) was significantly different (p<0.05) from the smaller 4.6% (p<0.01) decrease in the control group. Moreover, within the vitamin E group the decrease was even more marked over tertiles of α-tocopherol to LDL–LA ratio with a significant difference in decrease (p<0.05) from the lowest compared to the highest tertile of, respectively, 18.4% [−24; −2%] (median and range) and 2.0% [−16; 34%]. In conclusion, supplementation with 100 IU vitamin E in elderly is beneficial in lowering the rate of oxidation of LDL–LA. The protective effect of vitamin E might best be monitored by using the ratio of α-tocopherol to LDL–LA as this reflects the degree of α-tocopherol available to protect the amount of LDL–LA present.