Response of vitamin K status to different intakes and sources of phylloquinone-rich foods: comparison of younger and older adults

Background: Phylloquinone, found in dark-green vegetables and certain plant oils, is the primary dietary source of the fat-soluble vitamin K. Limited data suggest that the relative bioavailability of phylloquinone from vegeta bles is lower than that from a supplement. This finding is relevant to the maintenance of optimal vitamin K status. Objective: The objective of this study was to compare, in younger and older adults, the relative bioavailability of phylloquinone from a vegetable wit h that of a fortified oil. Design: In a crossover design with three 15-d residency periods in a metabo lic unit, younger and older men and women (n = 36) consumed a mixed diet co ntaining 100 mu g phylloquinone/d. During 2 residency periods, the mixed di et was supplemented for 5 d with either broccoli (377 mu g phylloquinone/d; broccoli diet) or phylloquinone-fortified oil (417 mu g/d; oil diet). The relative bioavailability of phylloquinone was defined by the difference in plasma phylloquinone, percentage serum undercarboxylated osteocalcin (%ucOC ), and urinary gamma-carboxyglutamic acid in response to 5 d of supplementa tion. Results: For both younger and older adults, plasma phylloquinone concentrat ions were higher (P < 0.001) and %ucOC values were lower (P = 0.001) after the broccoli and oil diets than after the mixed diet only. Overall, the res ponse to broccoli supplementation was not significantly different from the response to the fortified oil in either age group. Urinary gamma-carboxyglu tamic acid did not change in response to supplementation. Conclusions: There was no significant difference in the relative bioavailab ility of phylloquinone, as evidenced by the lack of a significant differenc e in plasma phylloquinone and %ucOC between the 2 groups after either the b roccoli or oil diets for younger and older adults.