Distribution of tocopherols in human plasma and red blood cells.

The content of various tocopherols was determined in normal plasma and red blood cells. alpha-Tocopherol concentrations ranged form 6.6 to 15.0 (mean 9.6) mug/ml in plasma and from 0.9 to 1.8 (mean 1.4) mug/ml in red blood cells. gamma-Tocopherol ranged from 0.7 to 2.7 (mean 1.6) mug/ml in plasma and fron 0.1 to 0.4 (mean 0.24) mug/ml in red blood cells. Only a minute amount (smaller than 0.3 mug/ml) of each of alpha-tocotrienol, beta-tocopherol, gamma-tocotrienol and delta-tocopherol was found in plasma but none in red blood cells. No delta-tochotrienol was detected in either plasma or red blood cells. Of the total tocopherols, alpha form accounted 83 per cent in plasma and 87 per cent in red blood cells and gamma from represented 13 per cent in each system. The recovery of added 14-C-alpha-tocopherol averaged 87 per cent and 69 per cent, respectively, for plasma and red blood cells. All alpha-tocopherol in the red blood cells was found to be localized in the membrane fraction.