Blood Thinning Medications (Anticoagulants) and Cancer

Blood thinning medications (also called anticoagulants) are prescribed for increased risk for developing a blood clot. Some chemotherapy medications cause an increased risk for blood clots. Having a history of previous blood clots or heart problems may also require a blood thinning medication. The medications that may be prescribed are: warfarin and enoxaparin. A blood test is used to monitor blood clotting time and determine the correct dosage. It is referred to as PT/INR (prothrombin time and international normalized ratio). The following are some tips to minimize any complications while taking a blood thinning medication:

Be familiar with Vitamin K.

  • Vitamin K is a vitamin that aids in blood clotting.
  • Vitamin K sometimes gets confused with Potassium. Potassium is a mineral.
  • The human body produces some Vitamin K. Foods, drinks, and vitamin/mineral supplements also contain vitamin K.
  • When too much vitamin K is consumed through foods, drinks, and vitamin/mineral supplements, it interferes with blood thinning medications as well as the blood test that measures clotting time.
  • It is most important to be consistent with vitamin K intake. Large variation or fluctuations in intake pose a problem when attempting to regulate clotting time and medication dosage.

Be familiar with the vitamin K content of foods, drinks, and supplements.  Foods and drinks containing vitamin K should be consumed in moderate, consistent amounts.

  • Vitamin K is most commonly found in high amounts in green vegetables such as: Broccoli, Brussels sprouts, Cabbage, Collard Greens, Endive, Kale, Leeks, Bibb Lettuce, Green Leaf Lettuce, Romaine Lettuce, Mustard Greens, Okra, Green Onions,  Green Peas, Sugar Snap Peas,  Spinach, Swiss Chard, Turnip Greens, Watercress, Soybeans (Edamame), and Cilantro.    
  • Limit high vitamin K foods to ½ cup per day.
  • Other foods to be aware of that contain a moderate amount of vitamin K 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.
  • Other beverages to avoid in large amounts are green tea and cranberry juice.
  • Avoid alcohol when taking any blood thinning medication.

It is most important to remember to eat about the same amount of Vitamin K every day.

  • Variation in Vitamin K level is what causes many problems when taking a blood thinning medication.
  • For example, it is not recommended to eat a moderately high vitamin K containing food such as blueberries at every meal. However, if this is a current dietary practice, do not abruptly discontinue doing so. It is best to keep vitamin K consumption constant while taking a blood thinning medication.

Be careful when using nutrition supplements.

  • Read the nutrition facts label for vitamin K content on liquid nutrition supplements.
  • Check the label on multivitamins for vitamin K content.
  • Do not take vitamin E or fish oil supplements while taking a blood thinning medication.
  • Avoid supplements or vitamins that have more than 100 mcg of vitamin K.
  • Once the decision to take multivitamin or supplement is made, be sure to take it every day.
  • Always get approval from your doctor or dietitian before taking any supplements or vitamins.  Any changes in multivitamin or supplement use should also be discussed.
  • According to the National Institute of Health Office of Dietary Supplements, it is best to avoid the following herbs when taking a blood thinning medication: alfalfa, arnica, bilberry, butcher’s broom, cat’s claw, dong quai, feverfew, forskolin, garlic, ginger, ginkgo, horse chesnut, inositol hexaphosphate, licorice, meililot (sweet clover), pau d’arco, red clover, St. John’s Wort, sweet woodruff, turmeric, willow bark, and wheat grass.