Dietary phylloquinone depletion and repletion in postmenopausal women: effects on bone and mineral metabolism.
BACKGROUND
Vitamin K has been implicated in increased bone fracture risk. Despite a potential role of vitamin K in bone, little is known about the effects of altered dietary phylloquinone intake on the underlying components of bone and mineral metabolism.


METHODS
A 84-day in-house dietary phylloquinone (vitamin K) depletion-repletion study was undertaken in 21 postmenopausal women (mean age: 70 years) to assess the effects of altered vitamin K status on intestinal calcium (Ca) absorption, urinary and serum Ca and phosphorus (P), serum calcemic hormones, and serum biomarkers of bone turnover [osteocalcin and N-telopeptide type 1 collagen cross-links (NTx)] and the response to 1,25-dihydroxyvitamin D treatment (1 microg/dayx7 d).


RESULTS
The group receiving calcitriol treatment (n=11) had higher Ca absorption, urinary Ca, urinary and serum P and serum osteocalcin and lower serum parathyroid hormone (PTH). There were no significant effects of acute (4-week) phylloquinone depletion on response to 1,25-dihydroxyvitamin D treatment or on measures of bone formation or mineral metabolism. However, phylloquinone treatment had a significant effect (p<0.04) on serum NTx. Phylloquinone repletion, up to five times (450 microg phylloquinone per day) the currently recommended adequate intake level of dietary phylloquinone for women, significantly reduced serum NTx (16.8+/-0.9 nmol bone collagen equivalents (BCE) per liter following repletion vs 18.4+/-1.1 nmol BCE per liter following depletion; p<0.01).


CONCLUSIONS
These findings suggest that altering vitamin K status in postmenopausal women by manipulating phylloquinone intake does not have an acute affect on intestinal Ca absorption, renal mineral excretion, or bone formation, but high phylloquinone intake may modestly reduce bone resorption. The impact of high phylloquinone intake on bone mineral density and fracture risk needs to be ascertained in randomized clinical trials.
Mineral Bioavailability Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, 711 Washington Street, Boston, MA 02111, USA.
L A
LA
Martini
S L
SL
Booth
E
E
Saltzman
M
M
do Rosário Dias de Oliveira Latorre
R J
RJ
Wood
D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000378:metabolism; D002117:Calcitriol / Q000627:therapeutic use*; D002118:Calcium / Q000378:metabolism*; D024042:Collagen Type I / Q000378:metabolism; D005260:Female; D006801:Humans; D008875:Middle Aged; D015675:Osteocalcin / Q000378:metabolism; D015663:Osteoporosis, Postmenopausal; D010281:Parathyroid Hormone / Q000097:blood; D010455:Peptides / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism*; D010837:Vitamin K 1; D014813:Vitamin K Deficiency / Q000150:complications* / Q000378:metabolism; D014815:Vitamins / Q000627:therapeutic use*
D015415:Biomarkers; D024042:Collagen Type I; D010281:Parathyroid Hormone; D010455:Peptides; D014815:Vitamins; C052929:collagen type I trimeric cross-linked peptide; D015675:Osteocalcin; D010758:Phosphorus; D010837:Vitamin K 1; D002117:Calcitriol; D002118:Calcium