Response of vitamin K status to varied intakes of phylloquinone

The response of vitamin K status to known dietary intakes of phylloquinone equivalent to or greater than the current RDA was compared among 36 healthy men and women residing in a metabolic ward for three 15-d periods, with a 6-wk washout between each period. A mixed diet of moderate fat (26% of total calories) which contained 100±12 μg of phylloquinone/day was consumed in all three periods. On d6 - d10 in two of the three periods, the mixed diet was supplemented with either broccoli or corn oil fortified with phylloquinone, thereby increasing the total dietary phylloquinone intake to 380 and 420 μg/d, respectively. The plasma phylloquinone concentrations were significantly higher in the older adults (60 - 80 y) as compared to the younger adults (20-40 y). Plasma phylloquinone concentrations and urinary gamma-carboxyglutamic acid (Gla) excretion significantly decreased (p<0.05) among young adults in response to the mixed diet, whereas there were no changes in either biochemical variable among the older adults. Both younger and older adults had significantly increased plasma phylloquinone concentrations in response to the broccoli and fortified oil (p<0.05). In contrast, there were no significant changes in urinary Gla excretion in response to broccoli or fortified oil for either age group. Blood coagulation as measured by prothrombin and activated partial prothrombin times, did not change during the study. On the basis of urinary Gla excretion and plasma phylloquinone concentrations, these data support suggestions that the current RDA for younger adults may require modification.