Dietary vitamin K intake and anticoagulation in elderly patients

Curr Opin Clin Nutr Metab Care. 2007 Jan;10(1):1-5. doi: 10.1097/MCO.0b013e328011c46c.


Purpose of review: Vitamin K is an essential co-factor for the synthesis of several coagulation factors. Oral anticoagulants competitively inhibit enzymes that participate in vitamin K metabolism. The purpose of this review is to evaluate the potential interaction of dietary vitamin K and coagulation stability, particularly in the elderly patient.

Recent findings: Recent prospective evidences suggest that dietary vitamin K plays an essential role in anticoagulation stability. Vitamin K intake of more than 250 microg/day was shown to decrease warfarin sensitivity in anticoagulated patients consuming regular diets. In a randomized crossover study, brief periods of changes on vitamin K intake also had significant effects on coagulation parameters. Patients that were allocated to an 80% decrease of intake increased International Normalized Ratio (INR) by almost 30% 7 days after the intervention. Similarly, it was estimated by dietary records that for each increase in 100 microg of vitamin K intake, the INR would be reduced by 0.2. A recent study also demonstrated that over-the-counter multivitamin supplements contain enough vitamin K1 to significantly alter coagulation parameters.

Summary: Contemporary data strengthen the concept that the interaction between dietary vitamin K and coumarin derivatives is clinically relevant and plays a major role in INR fluctuations in chronic anticoagulated patients.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Aged
  • Aging / blood*
  • Anticoagulants / administration & dosage*
  • Anticoagulants / therapeutic use
  • Antifibrinolytic Agents / administration & dosage*
  • Blood Coagulation / drug effects*
  • Diet
  • Food-Drug Interactions*
  • Humans
  • Phenprocoumon / administration & dosage
  • Thrombosis / prevention & control
  • Vitamin K / administration & dosage*
  • Warfarin / administration & dosage


  • Anticoagulants
  • Antifibrinolytic Agents
  • Vitamin K
  • Warfarin
  • Phenprocoumon