Warfarin (Brand name Coumadin) an anticoagulant normally used in the prevention of blood clot formation in the blood vessels and their migration elsewhere in the body whereas vitamin K is a nutrient which boost the natural body coagulant in the body.
Warfarin therapy is highly personalized, the blood of the patients taking warfarin are adjusted so that it is not easily form clot and the bleeding time are acceptable provided that the patients maintaining a stable diet.
By ingesting the vitamin K containing foods suddenly, you will be weaken the effect of warfarin and thus help the formation of blood clot in the blood vessels, these eventually lead to diseases such as stroke and heart attack.
On the other hand, if you suddenly stop taking your normal vitamin K containing food in your stable daily diet, the effect of warfarin is strengthen, and the bleeding time is prolong, you will be having trouble such as unstopable bleed, losing excessive blood.
So, it is important for patient taking warfarin to know which food containing high vitamin K and carefully choose the suitable foods.
Some of the examples of high vitamin K containing foods are: Kale, Spinach, parsley, broccoli, turnip greens.
My Pharmacist House 