Warfarin and Vitamin K

Warfarin is a small anticoagulant drug that is used to reduce the formation of blood clots. Most commonly, it is vitally used to prevent heart attacks, strokes or any blood clots in arteries or veins. Warfarin is a vitamin K antagonist. It inhibits the actions of clotting factors II, VII, IX and X in blood. This causes depletion of vitamin K functions and slows down the rate of blood clotting. 

Patients who had been prescribed with warfarin have to be more alert and concern on their vegetables intake. Most vitamin K can be found in green leafy vegetables. Never eliminate the intake of vegetables. The right way is to maintain or consistent in taking green vegetables. If the patients took ½ small cup of vegetables everyday, then maintain ½ small cup of vegetables after taking warfarin.

In addition, oil can affect the quantity of vitamin K in food. Oils also have high vitamin K such as canola oil, soybean oil and olive oil. However, heating oil in 20 minutes can reduce the content of vitamin K in 7%. Oils are not only a significant source of vitamin K, but it increases the absorption of vitamin K in foods.

Vitamin K content in commonly used oils is shown below:

Type of oil	Vitamin K (µg/100)*
Peanut	0.65
Corn	2.91
Safflower	9.13
Walnut	15
Sesame	15.5
Olive	55.5
Canola	141
Soybean	193

         *100g of oil is equivalent to 7 tablespoons          

A decreasing of INR can be seen when patients consume excess vitamin K than usual. There are some vegetables that are not green but high in vitamin K such as brussel sprouts and cabbage. Dietitians have to be more attentive on patients’ dietary and ensure a stable warfarin regime. Keep track the quantity of vitamin K consumed by patients on a weekly basis.

Reference: 

Nutescu, E. A., Shapiro, N. L., Ibrahim, S., & West, P. (2006). Warfarin and its interactions with foods , herbs and other dietary supplements.

(Source of picture) http://www.6minutes.com.au/news/latest-news/score-predicts-anticoagulant-bleeding-risk-