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 alpha-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 alpha-tocopherol to LDL-LA as this reflects the degree of alpha-tocopherol available to protect the amount of LDL-LA present.