Original Communication
European Journal of Clinical Nutrition (2005) 59, 900–905. doi:10.1038/sj.ejcn.1602154; published online 1 June 2005
The effect of 
-tocopherol administration on 
-tocopherol levels and metabolism in humans
S Yoshikawa1, T Morinobu2, K Hamamura3, F Hirahara4, T Iwamoto4 and H Tamai1
- 1Department of Pediatrics, Osaka Medical College, Osaka, Japan
- 2Seikeikai Hospital, Osaka, Japan
- 3Section-3 Process Research Laboratories, Eisai Co Ltd, Ibaragi, Japan
- 4Division of Food Science, Independent Administrative National Institute of Health and Nutrition, Tokyo, Japan
Correspondence: S Yoshikawa, Department of Pediatrics, Osaka Medical College, Daigakumachi, 2-7 Takatsuki, Osaka, Japan. E-mail: sosuke-no1@mrj.biglobe.ne.jp
Received 6 July 2004; Revised 8 March 2005; Accepted 9 March 2005; Published online 1 June 2005.
Abstract
Background:
The bioavailability of 
-tocopherol and metabolites of vitamin E after -tocopherol administration is not well understood. We investigated the effect of -tocopherol administration on the levels and metabolism of 
- and -tocopherol in healthy volunteers.
Methods:
We measured two metabolites of vitamin E (2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman (-CEHC) and 2,7,8-trimethyl-2-(2'-carboxyethyl)-6-hydroxychroman (-CEHC)) in plasma and urine by high-performance liquid chromatography with electrochemical detection (HPLC-ECD) during administration of -tocopherol. Two groups of volunteers were enrolled. The -tocopherol group received two -tocopherol capsules (each containing 186.4 mg of -tocopherol and 5 mg of -tocopherol) for 28 days, while the control group received d--tocopherol at 5 mg/day, which was the same dose as that given to the -tocopherol group. Blood and urine samples were obtained on days 0, 14, 28, 35, 42, and 56 after the initiation of -tocopherol administration.
Results:
The plasma -tocopherol concentration increased markedly during administration of -tocopherol and the plasma -CEHC concentration increased along with that of -tocopherol. The plasma -tocopherol concentration decreased significantly during -tocopherol administration. The plasma concentration of -CEHC decreased significantly and urinary excretion of -CEHC tended to increase in the -tocopherol group. Urinary sodium secretion was significantly increased at 1 week after the cessation of -tocopherol administration, but there was no significant difference of urine volume between the two groups.
Conclusion:
Metabolism of -tocopherol is accelerated and the plasma -tocopherol concentration is decreased during -tocopherol administration.
Keywords:
-tocopherol, -tocopherol, -CEHC, -CEHC, -tocopherol supplementation
