Measurement of vitamin E metabolites by high-performance liquid chromatography during high-dose administration of alpha-tocopherol.

Methods: alpha-Tocopherol and gamma-tocopherol are metabolized into 2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman (alpha-CEHC) and 2,7,8-trimethyl-2-(2'-carboxyethyl)-6-hydroxychroman (gamma-CEHC), respectively. We analyzed alpha- and gamma-CEHC concentrations in human serum and urine by high-performance liquid chromatography during administration of alpha-tocopherol. Fourteen healthy adult male volunteers received 1,200 IU per day of RRR-alpha-tocopherol for 28 days. Blood and urine samples were obtained on days 0, 14, 28, and 56.

Results: During alpha-tocopherol administration, the plasma gamma-tocopherol concentration decreased significantly, but there was marked elevation of the alpha-tocopherol concentration. Increased concentration of alpha-CEHC and gamma-CEHC in both serum and urine indicated the acceleration of vitamin E metabolism.

Conclusions: High-dose administration of alpha-tocopherol caused an increase of gamma-tocopherol metabolism, which might have caused a decrease of the plasma gamma-tocopherol concentration.