Determinants of Vitamin K Metabolism

Official Title: “Dietary and Non-Dietary Components of Vitamin K Metabolism”

The purpose of this study is to learn how the body responds to different amounts of vitamin K in the diet in order to understand the roles that vitamin K may have in the body. We also need to determine if older adults need more or less vitamin K in their diet compared to younger adults in order to maintain normal body stores of vitamin K.

Vitamin K has a role in bone health, but little is known about vitamin K metabolism in aging and in maintenance of bone mass. The limited understanding of vitamin K metabolism impedes the establishment of dietary recommendations for vitamin K, and the interpretation of results from clinical trials on vitamin K supplementation and bone health of women in a narrow age group. This study is the first to assess the role of dietary and other factors that influence the response to vitamin K status and bone turnover to vitamin K depletion and repletion in adults. This study also compares the absorption efficiency and body retention of vitamin K relative to current vitamin K status. Men and women [21 younger (18-40y) and 21 older (55+y)] will participate in a 62-d metabolic study, with a 5d run-in period, followed by a 28d dietary vitamin K restriction period (10 ug/d), and ending with a 28d dietary vitamin K supplementation period (500 ug/d). Coagulation times will be monitored during the dietary restriction period. Serial measurements of vitamin K status markers and of bone turnover markers will show the response of vitamin K to dietary manipulation for both age groups under identically controlled dietary conditions. Deuterium-labeled vitamin K in collards will be used to compare the absorption of vitamin K during a vitamin K-deplete state to that of a vitamin K-replete state. Vitamin K is transported in triglyceride-rich lipoproteins, which may vary among individuals due to differences in adiposity and lipid homeostasis. Therefore, measurement of body composition by DXA and plasma lipids will provide insight into the role of lipids in absorption and transport of vitamin K. The findings of this study are critical for the interpretation of the epidemiologic and clinical data used to determine the protective role vitamin K may have in chronic disease prevention.

Intervention(s) in this Clinical Trial

• Drug: Vitamin K
  • phylloquinone (vitamin K1) 500 mcg daily in third month

Primary Measures

• Urinary excretion of VK metabolites at VK depletion and repletion
  • Time Frame: 2 months
    Safety Issue?: No
• Bone turnover markers at VK depletion and repletion
  • Time Frame: 2 months
    Safety Issue?: No

Secondary Measures

• Plasma triglyceride levels at VK depletion and repletion
  • Time Frame: 2 months
    Safety Issue?: No
• Glucose metabolism measures at VK depletion and repletion
  • Time Frame: 2 months
    Safety Issue?: No
• Mood assessment at VK depletion and repletion
  • Time Frame: 2 months
    Safety Issue?: No

Inclusion Criteria:

-

Exclusion Criteria:

• kidney, GI, or liver disease requiring treatment
• prescribed osteoporosis medications in the previous 3 months
• use of acid reducers more than twice per week
• blood clotting disorder and/or abnormal clotting time
• warfarin or anticoagulant use in the previous 12 months
• diabetes
• smoking
• hormone therapy in the previous 3 months
• oral contraceptive use in the previous 3 months; pregnancy
• strict vegetarian diet

Gender Eligibility for this Clinical Trial: Both

Minimum Age for this Clinical Trial: 18 Years

Maximum Age for this Clinical Trial: N/A

Are Healthy Volunteers Accepted for this Clinical Trial?: Accepts Healthy Volunteers

Lead Investigator: Tufts University Other

Overall Clinical Trial Officials and Contacts

Sarah L Booth, PhD Principal Investigator Tufts Medical Center  

Information obtained from ClinicalTrials.gov on February 09, 2012

Link to the current ClinicalTrials.gov record. http://clinicaltrials.gov/show/NCT00336232

Study ID Number: R01 DK069341

ClinicalTrials.gov Identifier: NCT00336232

Health Authority: United States: Federal Government

Jean Mayer USDA Human Nutrition Research Center on Aging site