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The Vitamin K Conundrum

By Margaret Martin, RD, MS, LDN, CDCES January 20, 2016Pearls of Wisdom Blog

The blood’s ability to clot or not to clot is often a challenge in cancer care. Some chemotherapy and hormonal medications can increase the risk for blood clots. Lack of physical movement, surgery, and being confined to a bed can also increase this risk. Blood clots are not good the clots can stop the flow of blood to vital organs, starving them of oxygen. Death of body tissues, stroke, and heart attack are all possible results of a blood clot.

Thankfully, there are medications, called “blood thinners” (anticoagulants), which can help manage blood clots. These medications act to slow the time it takes for blood to clot so to prevent clots from forming. Examples of these drugs are warfarin, dalteparin, and enoxaparin. Warfarin has been around since the 1950’s. It is a pill you can take by mouth and costs less than the other two drugs. Warfarin requires blood testing to manage the dosages. Dalteparin and enoxaparin do not require blood tests.

Every patient is unique when it comes to the dosing requirements for warfarin (Coumadin), and blood tests are routinely done to make certain that the blood is anti-coagulated to the appropriate level. These tests are called PT (prothrombin time) tests, which are used to calculate your INR (international normalized ration). Your INR is used to determine the dosage of warfarin you need. There are numerous drug interactions with this medication that can cause the blood to become “too thin” such as some antibiotics, cholesterol-lowering drugs (called bile acid sequestrants), and some herbal supplements. Warfarin dosing always needs to be monitored by a healthcare professional, and a patient should never alter the dose of this medication without consulting with their healthcare professional.

So, what does all this have to do with vitamin K?

Vitamin K supports blood clotting and healthy bones. Your body needs vitamin K to stay healthy. Since warfarin slows blood clotting and vitamin K supports blood clotting, there has to be a balance between vitamin K intake from food, drinks, and supplements and the warfarin medication. Some people believe this means they shouldn’t eat foods with vitamin K at all while on warfarin, but this is NOT the case. Adults still need vitamin K for vital bodily functions, bone health, and overall wellness. If you are on warfarin, you just need to make sure you eat about the same amount of vitamin K daily to keep your INR stable. Keep it consistent! (Vitamin K does not affect the other medications like enoxaparin and dalteparin.)

What foods contain vitamin K?

Foods high in vitamin-K include: leafy green vegetables, broccoli, Brussel sprouts, soybeans, edamame, watercress, and cilantro. Of course, smoothies and soups made with these vegetables contain vitamin K. Liquid supplemental beverages and bars often have extra Vitamin K, too.

Foods with moderate levels of vitamin K sources include: asparagus, green beans, red cabbage, Chinese cabbage, carrots, cauliflower, red leaf lettuce, spaghetti sauce (marinara), sundried tomatoes, blackberries, kiwi fruit, grapes, blueberries, pumpkin, bean sprouts, cashews, soybean oil, thyme, and pickles.

Green tea and cranberry juice also contain vitamin K.

How can I balance vitamin K with my anticoagulants?

  • Take your medication at the same time every day, preferably at bedtime.
  • Eat about the same amount of vitamin K sources each day.
  • Learn which foods can be swapped that carry similar vitamin K content.
  • Measure the serving size for foods high in vitamin K. Don’t just guess.
  • Keep your blood testing and medical appointments.
  • Talk to your healthcare team and pharmacist about any other medications, dietary supplements, (especially vitamin E and herbal products) or over-the-counter products before you use them.
  • Just say no to alcoholic beverages which can change the way your body uses medications.
  • Ask your prescriber what to do if you forget to take a warfarin dose. Have a plan.
  • Let your healthcare team know if you change your diet, such as for weight loss, dental procedures, or during an illness.

Sources and additional resources:

National Institutes of Health

United States Department of Agriculture (USDA)

USDA National Nutrient Database

U.S. National Library of Medicine

Margaret Martin, RD, MS, LDN, CDCES

Author Margaret Martin, RD, MS, LDN, CDCES

Nutrition Educator Margaret Martin is a Licensed Dietitian and Nutritionist in the State of Tennessee as well as a Certified Diabetes Educator. Margaret graduated from the University of Alabama with a Bachelor of Science in Dietetics and received her Master’s Degree in Nutrition Science & Public Health from the University of Tennessee. With more than 10 years of experience in Clinical Nutrition, Margaret has also worked in the insurance industry with WellPoint Inc. and Blue Cross Blue Shield providing telephonic nutrition consultations, service assistance, and web-based nutrition education. In her free time Margaret volunteers with the American Lung Association’s annual “Lung Force Walk" in Middle Tennessee. She belongs to the Oncology Nutrition & Diabetes Care and Education Dietetic Practice Groups of the Academy of Nutrition and Dietetics.

More posts by Margaret Martin, RD, MS, LDN, CDCES

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