Current Projects

  • The Vitamin K Study: This is a metabolic study of 42 adults that is focused on the factors that influence response to vitamin K intake. We are examining age, current vitamin K status, body fatness, and lipid profile in a controlled metabolic setting. Use of stable isotopes (in collaboration with ARS/CNRC) has allowed us to refine our measures. The study will give us insight into the conversion of the dietary form of vitamin K to a different form found in certain tissues. NIH-NIDDK funded.
  • Conversion of phylloquinone to menaquinone-4 – We have developed a method for detecting an intermediate in this conversion that is present in urine and serum. We have also recently determined that high intakes of vitamins A and D influence this conversion. Conversion of phylloquinone to menaquinone-4 in different tissues is of interest because it implies that vitamin K in different forms has different biological functions. NIH-NIDDK funded.
  • New roles for vitamin K – unanticipated findings in our recently completed clinical trial (452 elderly men and women receiving control or vitamin K for 3 years) include: (1) elderly who have existing calcification in their coronary arteries have less progression of calcification if they receive vitamin K in amounts attainable in the diet; (2) older men who receive vitamin K supplementation have less progression of insulin resistance over 3 years; and (3) those who have high concentrations of biomarkers of inflammation have poor vitamin K status. NIH-NIA/NIAMS funded.
  • Characterize and quantify multiple forms of vitamin K in food samples representative of the US food supply. USDA cooperative agreement.
  • To examine the roles of apolipoprotein E, vitamin K epoxide reductase, and vitamin K-dependent gamma carboxylase genotypes in modulating vitamin K status. NIH-NIA funded.
  • To determine the role of vitamin K in modulation of inflammation. HNRCA pilot grant funding.
  • To evaluate the predictive value of circulating forms of vitamin K as a biomarker of healthy diets. NIH-NHLBI funded.
  • To evaluate the interaction of vitamin K status and genetic factors in determining response to the oral anti-coagulant warfarin. NIH-NHLBI funded.
  • To determine the interrelationship among long-chain menaquinones and gut microbiota. Collaboration with Dr. Liping Zhao at Shanghai Jiaotong University.
  • To determine the association between vitamin K status and knee osteoarthritis progression in older black and white men and women. Arthritis Foundation funded.