ASSESSMENT OF DIETARY PHYLLOQUINONE INTAKE AND VITAMIN-K STATUS IN POSTMENOPAUSAL WOMEN

Objective. To examine the relationship between dietary phylloquinone i ntake and vitamin K status of postmenopausal Caucasian women. Design. Cross-sectional study, in which dietary intake was estimated using wei ghed record techniques and vitamin K status was measured by a single p lasma phylloquinone concentration and 24-h urinary gamma-carboxyglutam ic acid (Gla) excretion. Setting: The metabolic research unit at the J ean Mayer USDA Human Nutrition Research Center on Aging at Tufts Unive rsity, Boston, MA. Subjects: 402 healthy postmenopausal Caucasian wome n who were participating in a randomized trial to determine the effect of calcium supplementation on bone loss. Of the original group, 362 h ad complete weighed diet records, 358 had corresponding plasma phylloq uinone concentrations, and 346 had corresponding urinary Gla measureme nts. Results: There was a significant correlation (r = 0.13, P = 0.01) between total dietary intake of phylloquinone (geometric mean = 89 mu g/day) and plasma phylloquinone levels (mean = 1.12 nmol/l). Dietary intake was neither correlated with urinary Gla excretion (mean = 4.0 m u mol/mmol creatinine) nor did it vary by season. The ratio of intra- to interindividual variance in phylloquinone intake was 2.6, from whic h it was estimated that 5 days of independent recording is necessary t o estimate true usual dietary intake, assuming a correlation of 0.8. C onclusions: A weighed record has the potential to be a reliable method for estimating dietary intakes of vitamin K which relate to plasma ph ylloquinone levels used as an indicator of vitamin K status in postmen opausal Caucasian women.