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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #201731
Title: Dietary phylloquinone depletion and repletion in postmenopausal women: effects on bone and mineral metabolism

Author
item MARTINI, LIGIA - UNIV SAO PAULO, BRAZIL
item Booth, Sarah
item SALTZMAN, EDWARD - TUFTS/HNRCA
item LATORRE, MARIA - UNIV SAO PAULO, BRZAIL
item Wood, Richard

Submitted to: Osteoporosis International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2006
Publication Date: 3/18/2006
Citation: Martini, L.A., Booth, S.L., Saltzman, E., Latorre, M., Wood, R.J. 2006. Dietary phylloquinone depletion and repletion in postmenopausal women: effects on bone and mineral metabolism. Osteoporosis International. 17(6):929-35.

Interpretive Summary: 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 vitamin K intake on the underlying components of bone and mineral metabolism. This study was undertaken to assess the effects of vitamin K depletion and repletion on calcium and bone metabolism in elderly women. Twenty-one postmenopausal women participated in a 3-month in-house metabolic study that consisted of consecutive dietary phases during which they were fed a low vitamin K depletion diet fortified with varying levels of vitamin K. To assess whether vitamin K status affected vitamin D-dependent mineral metabolism, subject were randomized to receive the active hormonal form of vitamin D or no treatment for three 1-week periods during the last week of the 2-week baseline, 4-week depletion and 6-week repletion phases of the study. Dietary Vitamin K depletion resulted in a lowering of vitamin K status in the women, but there was no change in calcium or bone metabolism. Likewise, giving the active form of vitamin D changed bone and mineral metabolism as expected, but neither vitamin K depletion nor vitamin K supplementation has a marked effect on most study measures. Vitamin K supplementation did however lower bone breakdown slightly based on biomarker measures in these older women. We believe that vitamin K intervention trials will be necessary to clear delineate the influence of vitamin K status on the skeleton.

Technical Abstract: 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 vitamin K intake on the underlying components of bone and mineral metabolism. This study was undertaken to assess the effects of vitamin K depletion and repletion on intestinal calcium (Ca) absorption, urinary and serum Ca and phosphorus (P), serum calcemic hormones, and biomarkers of bone turnover (osteocalcin and N-telopeptide type 1 collagen cross-links (NTx)) in elderly women. Twenty-one postmenopausal women participated in a 3-month in-house metabolic study that consisted of consecutive dietary phases during which they were fed a low vitamin K depletion diet fortified with varying levels of vitamin K. To assess whether vitamin K status affected vitamin D-dependent mineral metabolism, subject were randomized to receive either 1,25-dihydroxycholecalciferol (1 µg calcitriol /d x 7d) or no treatment for three 1-week periods during the last week of the 2-week baseline, 4-week depletion and 6-week repletion phases of the study. A significant change in vitamin K status during the study was confirmed by an increase in blood PIVKA-II concentration (a marker of hepatic vitamin K depletion) following the dietary vitamin K depletion phase that returned to normal following 6 weeks of vitamin K repletion. The group receiving calcitriol treatment had higher Ca absorption, urinary Ca, urinary and serum P, serum osteocalcin (a marker of bone formation) and lower serum PTH. Serum NTx (a marker of bone resorption) was significantly reduced at the end of the vitamin K repletion period. There were no significant calcitriol x vitamin K treatment interactions. These findings suggest that dietary vitamin K intake does not affect intestinal Ca absorption, renal mineral excretion, or bone formation, but may influence bone resorption in elderly women.