RESUMEN
The concentrations of lipid-soluble, chain-breaking antioxidants in human plasma and in erythrocyte ghosts have been determined for the first time by an inhibited autoxidation method. The results are very similar to the concentrations of vitamin E measured for the same blood components by the HPLC method. It is concluded that vitamin E, which is largely present as α-tocopherol, is the only significant lipid-soluble, chain-breaking type of antioxidant present in human blood. The concentration of vitamin E in the plasma lipids divided by the concentration of vitamin E in the ghost membrane lipids is approximately a constant despite the large differences in vitamin E-intake and in plasma lipid concentrations in different individuals. Vitamin E/lipid ratios for plasma and ghosts were larger for subjects taking a supplement of α-to- copherol acetate of 100 IU per week, compared to nonsupplemented subjects (based on data from a limited number of subjects). A larger supplement of 2800 IU per week did not significantly increase the vitamin E/lipid ratios.