Age group and sex do not influence responses of vitamin K biomarkers to changes in dietary vitamin K

Abstract

Inadequate vitamin K intake has been associated with abnormal soft tissue calcification. Older adults may have insufficient intakes of vitamin K and respond less to vitamin K supplementation compared with younger adults. However, little is known about the determinants that influence the response to vitamin K supplementation. Our primary objective was to assess dietary and nondietary determinants of vitamin K status in healthy younger and older adults. In a nonrandomized, nonmasked study, 21 younger (18-40 y) and 21 older (55-80 y) men and women consumed a baseline diet (200 μg phylloquinone/d) for 5 d, a phylloquinone-restricted diet (10 μg phylloquinone/d) for 28 d, and a phylloquinone-supplemented diet (500 μg phylloquinone/d) for 28 d. Changes in vitamin K status markers in response to vitamin K depletion and repletion were studied and the influences of BMI, body fat, and circulating TG were assessed by including them as covariates in the model. Despite baseline differences in measures of vitamin K status, plasma phylloquinone tended to increase (P = 0.07) and the percentage of uncarboxylated osteocalcin and uncarboxylated prothrombin both improved with phylloquinone supplementation (P < 0.007), regardless of age group or sex. Only the excretion of urinary menadione, a vitamin K metabolite, was greater among younger adults in response to depletion than in older adults (P = 0.012), regardless of sex. Adiposity measures and circulating TG did not predict response of any measures. In conclusion, poor vitamin K status can be similarly improved with vitamin K supplementation, regardless of age group or sex.

Conflict of interest statement

Author disclosures: J. T. Truong, X. Fu, E. Saltzman, A. Al Rajabi, G. Dallal, C. Gundberg, and S. Booth, no conflicts of interest.

Figures

FIGURE 1

Circulating phylloquinone (A), percentage ucOC (B), and PIVKA-II (C) in younger (20–40 y) and older (55–80 y) men and women when they consumed 200 μg/d (baseline), 10 μg/d (depletion), and 500 μg/d (supplementation) phylloquinone. Values are means ± SEM, n = 9 (younger men, older women) or 12 (younger women, older men). In all participants, plasma phylloquinone decreased in response to depletion (P < 0.001) and percentage ucOC and PIVKA-II increased (P < 0.001). All markers reversed direction in response to repletion (P < 0.001). PIVKA-II, protein induced in vitamin K absence or antagonism – Factor II; ucOC, uncarboxylated osteocalcin.

FIGURE 2

Urinary menadione (A) and Gla (B) excretions in younger (20–40 y) and older (55–80 y) men and women when they consumed 200 μg/d (baseline), 10 μg/d (depletion), and 500 μg/d (supplementation) phylloquinone. Values are mean ± SEM, n = 9 (younger men, older women) or 12 (younger women, older men). In all participants, urinary menadione decreased in response to depletion (P < 0.05). Urinary menadione and Gla reversed direction in response to repletion (P < 0.05). Labeled mean differences in response to phylloquinone depletion (d5–34) or supplementation (d34–61) without a common letter differ by age group, P < 0.05. Gla, γ-carboxyglutamic acid.

FIGURE 3

Serum NTx (A) and total OC (B) in younger (20–40 y) and older (55–80 y) men and women when they consumed 200 μg/d (baseline), 10 μg/d (depletion), and 500 μg/d (supplementation) phylloquinone. Values are means ± SEM, n = 9 (younger men, older women) or 12 (younger women, older men). There were no significant changes in either NTx or total OC in response to depletion or repletion. NTx, cross-linked N-telopeptide of type 1 collagen; OC, osteocalcin.