Abstract
BackgroundAn adverse hematological interaction between vitamins E and K has been reported, primarily in patients on anticoagulants. However, little is known regarding circulating levels or tissue concentrations of vitamin K in response to vitamin E supplementation. The purpose of this study was to examine the effect of different levels of dietary α-tocopherol on phylloquinone and menaquinone-4 concentrations, while maintaining a constant intake of phylloquinone, in rat tissues.MethodsMale 4-wk old Fischer 344 rats (n = 33) were fed one of 3 diets for 12 wk: control (n = 13) with 30 mg all-rac-α-tocopherol acetate/kg diet; vitamin E-supplemented (n = 10) with 100 mg all-rac-α-tocopherol acetate/kg diet; and vitamin E-restricted (n = 10) with <10 mg total tocopherols/kg diet. All 3 diets contained 470 ± 80 μg phylloquinone/kg diet.ResultsPhylloquinone concentrations were lower (P ≤ 0.05) in the vitamin E-supplemented compared to the vitamin E-restricted group (mean ± SD spleen: 531 ± 58 vs.735 ± 77; kidney: 20 ± 17 vs. 94 ± 31, brain: 53 ± 19 vs.136 ± 97 pmol/g protein respectively); no statistically significant differences between groups were found in plasma, liver or testis. Similar results were noted with menaquinone-4 concentrations in response to vitamin E supplementation.ConclusionThere appears to be a tissue-specific interaction between vitamins E and K when vitamin E is supplemented in rat diets. Future research is required to elucidate the mechanism for this nutrient-nutrient interaction.
Highlights
An adverse hematological interaction between vitamins E and K has been reported, primarily in patients on anticoagulants
The naturally occurring forms of vitamin K are quinones so vitamin K is reduced to the vitamin K hydroquinone prior to catalyzing the γ-carboxylation reaction [11]
The active site for the carboxylation reaction is on the napthoquinone ring, which is identical for all forms of vitamin K, including phylloquinone and MK-4
Summary
An adverse hematological interaction between vitamins E and K has been reported, primarily in patients on anticoagulants. The purpose of this study was to examine the effect of different levels of dietary α-tocopherol on phylloquinone and menaquinone-4 concentrations, while maintaining a constant intake of phylloquinone, in rat tissues. Doses of vitamin E at the Tolerable Upper Level [5] can result in an increase in the under γ-carboxylation of prothrombin, an indicator of poor vitamin K status, in adults with normal coagulation status [6]. Doses of 600 IU of natural-source vitamin E administered on alternative days were associated with a modest increase in risk of epistaxis in the Women's Health Study [7]. These outcomes suggest an interaction between vitamin E and vitamin K in humans. The active site for the carboxylation reaction is on the napthoquinone ring, which is identical for all forms of vitamin K, including phylloquinone and MK-4
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