Recent research conducted by Japanese investigators studied the impact of orally administered α-tocopherol on γ-tocopherol and tocotrienol depletion. Rats fed either a γ-tocopherol rich diet or a tocotrienol rich diet for 6 weeks were followed by a γ-tocopherol or tocotrienol free diet with or without α-tocopherol. The results showed that dietary α-tocopherol did not influence γ-tocopherol and tocotrienol concentrations in serum as well as liver, adrenal, small intestine, heart and adipose tissue. Additionally, urinary excretion of γ-tocopherol and tocotrienol metabolites were not affected.
T. Uchida T, et al. Alpha-tocopherol does not accelerate depletion of gamma-tocopherol and tocotrienol or excretion of their metabolites in rats. Lipids. Vol. 48, No. 7, 687-695