Vitamin K: a practical guide to the dietary management of patients on warfarin

• Published in: Nutrition reviews Vol. 57; no. 9; pp. 288 - 296
• Main Authors: Booth, S.L, Centurelli, M.A
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-09-1999; International Life Sciences Institute
• Subjects: Anticoagulants - pharmacology; Biological and medical sciences; Diet; Drug Interactions; Food Analysis; food composition; food composition tables; guidelines; Humans; Medical sciences; Miscellaneous; nutrient content; nutrient intake; nutrient-drug interactions; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); Vitamin K - administration & dosage; Vitamin K - analysis; Vitamin K - therapeutic use; vitamin k compounds; warfarin; Warfarin - pharmacology; Human; Warfarin; Coumarine derivatives; Molecular interaction; Handbook; Feeding; Antagonism; Clinical management; Diet therapy; Diet; Chemical composition; Food; Vitamin K
• ISSN: 0029-6643; 1753-4887
• DOI: 10.1111/j.1753-4887.1999.tb01815.x

Warfarin has been successfully used in the medical management of thromboembolic disease for nearly six decades. It is widely assumed that a dietary vitamin K-warfarin interaction exists. To avoid this potential interference with the efficacy of warfarin in stable anticoagulation, patients typically receive instructions to consume a constant dietary intake of vitamin K. While dark, green vegetables are primary sources of dietary vitamin K, these foods are not commonly consumed on a daily basis in the United States. However, there still exists dietary resistance to warfarin that is attributable to vitamin K. Based on food analysis studies on vitamin K, it is now known that dietary vitamin K is found in certain plant oils and prepared foods containing these plant oils, such as baked goods, margarines, and salad dressings. The preparation of foods with vitamin K-rich oils may also contribute to a diet-warfarin interaction, although this has yet to be confirmed in a clinical trial. A dose-response of vitamin K on the effect of warfarin anti-coagulation has not yet been established. However, there are sufficient data to suggest that a constant dietary intake of vitamin K that meets current dietary recommendations of 65-80 microgram/day is the most acceptable practice for patients on wafarin therapy. Vitamin K composition data for commonly consumed foods are now available and may facilitate successful anticoagulation for patients being treated with warfarin.