Food and Drug Interactions

Which foods have the greatest potential to interfere with the therapeutic effect of coumadin, statins, and diuretics?

Grapefruit, citrus fruits, mixed greens, tuna have the most potential to interfere with coumadin due to high vitamin k content. Grapefruit has the highest potential to interfere with the metabolism of statins by downregulating CYP3A4. Foods high in potassium can cause elevated potassium with potassium-sparing diuretics. If taking loop diuretics, you will need to increase your potassium, chloride, thiamin, zinc, and magnesium intake as these cause urinary losses in these nutrients (Gropper, Smith, & Carr, 2018).

Find the Food Ranking Tool Here To See Micro and Macro Nutrients in Each Food

Vitamin K Containing Food List

The American Heart Associations list of 19 foods high in vitamin K includes: (Kandola, 2019)

  • amaranth leaves
  • asparagus
  • broccoli
  • Brussels sprouts
  • coleslaw
  • collard greens
  • canned beef stroganoff soup
  • endive
  • garden cress
  • kale
  • kiwifruit
  • lettuce
  • mustard greens
  • soybeans
  • spinach
  • Swiss chard
  • tuna fish in oil
  • turnips
  • vegetable drinks

Why is this important?

Coumadin slows the production of clotting factors by decreasing the active form of vitamin k that is required for clotting factor production. So ingestion of foods high in vitamin k will counteract the blood-thinning effects of coumadin. Limiting foods containing vitamin k to 60-80 mcg per day is the goal (Kandola, 2019).

Grapefruit may increase the absorption of statin drugs without metabolism leading to elevated blood levels of the statin. This causes more side effects and potential toxicity (Gropper, Smith, & Carr, 2018). Foods high in potassium may elevate potassium levels with potassium-sparing diuretics raising the risk of cardiac arrhythmias (Health Essentials from Cleveland Clinic, 2020).

Gropper, S. S., Smith, J. L., & Carr, T. P. (2018). Advanced Nutrition and Human Metabolism (7th ed.). Cengage Learning. https://doi.org/10.1111/j.1753-4887.1997.tb01621.x

Health Essentials from Cleveland Clinic. (2020). How What You’re Eating Could Be Affecting Your Medications. https://health.clevelandclinic.org/how-what-youre-eating-could-be-affecting-your-medications/

Kandola, A. (2019). What to know about the warfarin diet. Medical News Today. https://www.medicalnewstoday.com/articles/324419#summary

*These statements are not meant to diagnose or treat. You should consult your health care provider before starting any new diet, exercise, or supplement.