Mechanism of enhancing vitamin E activity by sesame seed or its lignans

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Mechanisms enhancing vitamin E activity by sesame seed or its lignans were investigated in two experiments.In experiment 1 we examined whether or not the excretion of gamma-tocopherol (Toc) into the bile is suppressed by sesame seed intake, It has been well known that alpha-Toc content is much higher than gamma-toc in the plasma and liver of humans and rats. It has thus been assumed that gamma-Toc, which cannot bind with the alpha-Toc transfer protein is excreted into the bile. However, in a previous experiment, we observed that gamma-Toc content in the plasma and liver was higher in rats fed a sesame seed containing diet than in a gamma-Toc diet with the same gamma-Toc intake. We supposed that sesame seed suppresses gamma-Toc excretion into the bile, so we determined the gamma-Toc contents in the plasma, liver and bile. We found unexpectedly that more gamma-Toc was excreted into the bile when its concentration in the liver was high, and that less gamma-Toc was excreted when its concentration in the liver was low. The very low gamma-Toc concentrations in the liver and bile suggest that gamma-Toc was destroyed very quiclky and the sesame seed may suppress gamma-Toc destruction.In experiment 2 we examined whether or not sesaminol enhanced tocopherol adsorption. Rats were divided into three groups. Group 1 received a diet contatining 20 mg of tocopherol and tocotrienol mixture (Tmix), group 2 received a diet containing 20 mg Tmix with 0.1% sesaminol, and group 3 received either a diet containing 40 mg Tmix or the same diet alternating with 0.2% sesaminol diet without Tmix every other day. Group 1 showed vitamin E deficient status but group 2 and 3 showed significant improvement of vitamin E status. The enhancing effects of vitamin E activities in group 2 and 3 were nearly the same. These results indicated that sesaminol did not cause an enhanced absorption of tocopherol.