Coumadin is a medication that thins out the blood and vitamin K is a nutrient that helps form blood clots. The two work against each other within the body during the production of blood clot formation. To not interfere with the effectiveness of coumadin, dietary intake of vitamin K needs to be controlled.
The Role of Vitamin K
Vitamin K is a nutrient involved in the blood clotting process by stimulating the liver to increase production of prothrombin, which is a blood protein that is part of the clotting process. If the diet contains too little or too much vitamin K, prothrombin levels are affected, which ultimately either slows down or speeds up blood clot formation.
Interaction Between Vitamin K and Coumadin
Eliminating vitamin K from the diet will not improve the effectiveness of coumadin. Vitamin K is found in many healthy foods, including many vegetables. Therefore, it is neither ideal nor realistic to avoid foods with vitamin K for as long as coumadin is required. Instead, vitamin K should be consumed consistently on a daily basis.
Daily Dosage of Vitamin K While on Coumadin
Foods that are a high source of vitamin K should be limited to ½ cup per day. These include collard greens, kale, turnip greens, mustard greens, spinach, swish chard, beet greens and raw parsley. Foods that are a moderately high source of vitamin K should be eaten in approximately the same amount every day, such as one or two cups. The same food does not have to be consumed every day, rather it can be any food from that group. These foods include Brussels sprouts, all types of lettuce, broccoli, onions, egg or spinach noodles, okra, cabbage, prunes, rhubarb, and black-eyed peas.
Additional Sources of Vitamin K
Vitamin K is found in some nonfood sources, such as multivitamin and herbal supplements. To ensure there are no other drug-nutrient or drug-herb interactions while taking coumadin, consult your doctor to review all supplements you take.
References
- "Structure and Function of the Body, 13th Edition"; Gary Thibodeau, et al.; 2008
- Clinical Center National Institute of Health Drug-Nutrient Task Force;Important Information to Know When You Are Taking Coumadin and Vitamin K; 2003
- U.S. Department of Argiculture: National Nutrient Database for Vitamin K
