γ-Tocopherol Is Metabolized Faster than α-Tocopherol in Young Japanese Women.

To elucidate the characteristics of gamma-tocopherol metabolism, serum concentrations of alpha- and gamma-tocopherol, and urinary excretion of their metabolites after ingestion of a-or g-tocopherol, major isoforms in our diet, were compared. Six healthy Japanese women (age 22.7 +/- 1.7 y old, BMI 21.4 +/- 0.9) ingested 134 mg of alpha- or gamma-tocopherol, and blood and urine were collected until 72 h later. After alpha-tocopherol intake, the serum concentration of a-tocopherol increased at 12-24 h, and urinary excretion of 2,5,7,8-tetramethyl-2-( 2 alpha-carboxyethyl)-6-hydroxychroman (alpha-CEHC), an alpha-tocopherol metabolite, increased at 12-36 h. However, after gamma-tocopherol intake, the serum concentration of gamma-tocopherol increased at 6-12 h, and excretion of 2,7,8-trimethyl-2(2'-carboxyethyl)-6-hydroxychroman (g-CEHC), a gamma-tocopherol metabolite, increased at 3-12 h. The area under the curve from 0 to 72 h and serum maximal concentration of gamma-tocopherol were lower than those of alpha-tocopherol. The time to maximal concentration of gamma-tocopherol was faster than that of alpha-tocopherol. The ratio of urinary excretion of carboxyethyl-hydroxychroman to tocopherol intake was 2.9% for alpha-CEHC and 7.7% for gamma-CEHC. These results revealed that g-tocopherol is metabolized faster than alpha-tocopherol in healthy young women.