Determinants of plasma vitamin E concentrations.

Vitamin E, a lipid soluble antioxidant, is transported in plasma lipoproteins. This review will summarize the mechanisms for the preferential incorporation of RRR-alpha-tocopherol into lipoproteins. Special attention is devoted to the hepatic tocopherol binding protein, and to patients who are vitamin E deficient because they apparently have a genetic defect in this protein. The regulation of plasma vitamin E by the tocopherol binding protein as a determinant of the biologic activity of various forms of vitamin E is also discussed.