Yu-Wen Wang and Chia-Hsien Chang contributed equally.
A practical approach to minimize the interaction of dietary vitamin K with warfarin
Article first published online: 28 OCT 2013
© 2013 John Wiley & Sons Ltd
Journal of Clinical Pharmacy and Therapeutics
Volume 39, Issue 1, pages 56–60, February 2014
How to Cite
Chang, C.-H., Wang, Y.-W., Yeh Liu, P.-Y. and Kao Yang, Y.-H. (2014), A practical approach to minimize the interaction of dietary vitamin K with warfarin. Journal of Clinical Pharmacy and Therapeutics, 39: 56–60. doi: 10.1111/jcpt.12104
- Issue published online: 3 JAN 2014
- Article first published online: 28 OCT 2013
- Manuscript Accepted: 23 SEP 2013
- Manuscript Received: 13 OCT 2012
- vitamin K;
What is known and objective
The many interactions between warfarin and other drugs and foods generate great challenges for clinicians and patients in maintaining stable anitcoagulation. Interactions due to variable vitamin K content of different dietary items influence the therapy of nearly all patients on warfarin. Unfortunately, there is no widely acceptable, patient-friendly strategy for managing such interactions. In this contribution, we propose a practical approach to managing this troublesome interaction, consisting of ‘maintaining constant weekly dietary vitamin K intake scores’.
Twenty-three vitamin K-rich vegetables commonly seen in Taiwanese meals were identified and classified into seven score grades according to their relative vitamin K content per serving. The scores were based on published vitamin K content of different foods.
Results and discussion
The vitamin K score was equivalent to 5 points for spinach and garland chrysanthemum per bowel, followed by (baby) bok choy, amaranth, arden lettuce (4 points); leaf mustard, edible rape, sweet potato leaf, bai cai and Chinese leek (3 points); and okra and Chinese celery (0·5 points). This classification can be used to guide patients in recording their weekly vitamin K scores with a view to maintaining it when on warfarin.
What is new and conclusion
We suggest a novel approach to patient counselling on warfarin to maintain consistent dietary vitamin K intake and achieve a more stable anticoagulation response. A prospective randomized controlled trial to validate this pragmatic approach would be useful.