Excess α-tocopherol decreases extrahepatic phylloquinone in phylloquinone-fed rats but not menaquinone-4 in menaquinone-4-fed rats.

Scope: The effects of vitamin E on vitamin K metabolism were elucidated by comparing the effect of tocopherol intake on vitamin K concentrations in rats fed phylloquinone (PK) or menaquinone (MK)-4. Methods and results: Initially, the dietary effect of RRR-alpha-tocopherol, but not RRR-gamma-tocopherol, in decreasing extrahepatic PK concentrations was confirmed. Subsequently, rats were fed a PK or MK-4-containing diet (0.75 mg/kg) with RRR-alpha-tocopherol (0, 10, 50, or 500 mg/kg) for 6 weeks. In rats fed PK, alpha-tocopherol consumption decreased PK in kidney, lung, heart, muscle, testis, and brain but not in serum and liver. However, in rats fed MK-4, alpha-tocopherol consumption did not decrease MK-4 in serum and tissues. Finally, vitamin K-and E-depleted rats were administered PK or MK-4 (0.2 mg) with RRR-alpha-tocopherol (0, 1, or 10 mg) by gavage. After PK administration, alpha-tocopherol was observed to decrease PK in kidney, adrenal gland, lung, testis, and brain but not in serum and liver, whereas, after MK-4 administration, alpha-tocopherol did not affect MK-4 in serum and tissues. Conclusion: Excess alpha-tocopherol decreased extrahepatic PK in rats fed PK but not MK-4 in rats fed MK-4.