Vitamin K - How much is too much?

What is the “right” amount of vitamin K for patients taking warfarin? This is a very common question. A simple answer is not possible. Every patient is different, so it is very difficult to apply a “one size fits all” recommendation. A patient’s size, age and sex affect the amount of vitamin K necessary for normal body functioning.

Vitamin K remains a difficult concept for patients to understand. The first principle is the relationship between vitamin K and warfarin. Vitamin K will reduce the effect of warfarin over time. High intake of vitamin K will lower a patient’s International Normalized Ratio (INR). The impact on warfarin is related to the amount and frequency of vitamin K consumed.

Although common in many vegetables, particularly green vegetables, vitamin K is not limited to vegetables; it is common in cooking oils, salad dressings and in some beverages. The more vitamin K and the longer a patient ingests vitamin K products, the greater the suppression of warfarin will take place.

The second principle of understanding vitamin K is the difficulty of managing or even remembering the thousands of foods that contain vitamin K. Patients are encouraged to eat a balanced, healthy meal and monitor their foods so the dose of warfarin can be adjusted to their diet preferences. A warfarin lifestyle does require patients to become educated on the vitamin K content of food. Much like a diabetic carefully monitors sugar intake, warfarin patients need to monitor vitamin K. Using of the vitamin K registry on the home page will help.

Since vegetables are the most common source of vitamin K, patients should use the vitamin K diary around the dozen or so favorite vegetables they’re most likely to consume between INR blood tests.

According to the United States Department of Agriculture, the recommended range of normal vitamin K intake ranges between 60-80 micrograms for women and 80-120 micrograms for men. Vitamin K is an important vitamin to maintain bone growth and bone density as well as support blood clotting.

The “right” amount of vitamin K is the amount consumed with a fixed dose of warfarin to produce an INR within the patient’s target range time and time again. This could include lower dose of warfarin and lower than recommended vitamin K intake or a higher dose of warfarin and higher intake of vitamin K. Your vitamin K intake amount should to be determined your doctor. The goal is to eat a healthy diet and have blood tests in their target range. When both these goals are met, the ideal vitamin K level has been reached.