Certain foods and beverages can affect how your warfarin works. This handout will help you to plan your diet when taking warfarin.

When we cut or scrape our skin, our blood forms a clot (or plug) so that we don't bleed too much. Vitamin K helps our blood to clot. Vitamin K is found in various foods that we eat. Green leafy vegetables are rich in vitamin K.

Some diseases and conditions can cause the blood to clot too much. When this happens, blood clots can form in the body and block blood flow. This can cause heart attack, stroke, deep vein thrombosis and other serious health problems.

If your blood clots too much, your doctor may prescribe warfarin.

• Warfarin is a pill that prevents blood clots.
• Warfarin makes your blood clot slower.
• Vitamin K has the opposite effect of warfarin and helps your blood to clot more quickly.
• Your warfarin dose will be balanced with the amount of vitamin K in your usual diet to make your blood clot at a safe rate.

Therefore, it is important to eat the same amount of Vitamin K each day so that your medication works at its best.

Steps You Can Take

Follow a healthy and well-balanced diet. You do not need to stop eating green leafy vegetables that are rich in vitamin K. Vitamin K is needed for good health.

To keep your warfarin working well:

• Avoid large changes in the amount of vitamin K you eat from one day to another.
• Try to prepare foods in the same way. If you normally eat cooked leafy green vegetables do not suddenly start eating them just raw. Since green leafy vegetables wilt when cooked, the cooked version can have more vitamin K than the raw version.
• Talk to your doctor before eating natto (fermented soybean), grapefruit, Seville, or tangelo oranges or their juices, pomegranate juice, cranberries or cranberry juice, avocado, fish oil, flaxseed oil, mango, papaya, soy beverage, sushi with seaweed, goji berry, and chamomile tea. These foods may change how warfarin works in your body.

Talk to your doctor before making any changes to your diet.

This includes if:

• You plan to eat more green leafy vegetables (for example, you eat more vegetables in the spring and summer).
• You get the flu and are unable to eat solid foods for a few days.
• You have been in the hospital on a limited diet (due to surgery or illness) and return home to your normal diet.
• You plan to travel to a place where the foods are different.

If you make changes to your diet, your doctor may need to check your INR (blood clotting test) more often, or change your dose of warfarin.

The chart below is a list of green leafy vegetables and their vitamin K content. You can eat any of these foods as long as the total amount (mcg) of vitamin K you eat is about the same each day.

• If your INR is stable and in safe range, keep eating the foods you normally eat.
• If your INR is unstable (sometimes too high and sometimes too low) use the chart below to add up how much vitamin K you are eating each day.

*Nutrient information taken from Canadian Nutrient File (2015)

https://food-nutrition.canada.ca/cnf-fce/index-eng.jsp

Other Tips

Alcohol

• For most people, moderate alcohol intake does not change the way warfarin works.
• If you drink alcohol, limit it to:
  • 10 drinks a week for women, with no more than 2 drinks a day
  • 15 drinks a week for men, with no more than 3 drinks a day.
• One standard drink is a:
  • 341 mL (12 oz) bottle of beer
  • 142 mL (5 oz) glass of wine
  • 43 mL (1.5 oz) serving of spirits.

Vitamin and Mineral Supplements

• If you take a vitamin or mineral supplement that contains vitamin K, take it consistently every day. Many multivitamin and some calcium and vitamin D supplements contain vitamin K.
• Supplements that don't contain vitamin K can still interact with warfarin.

Natural Health Products (e.g. plant-based supplements)

• Tell your doctor about any extracts, powders or pills that you currently take. This includes nutritional supplements (such as garlic pills, flax seed oil, and fish oils) and herbal medicines (including herbal teas).
• Many natural health products interfere with warfarin. Some may have effects on warfarin that have not yet been reported.

Talk to your doctor if you have any questions

• about alcohol use
• before starting or stopping any vitamin or mineral supplements
• starting or stopping any natural health products.

Additional Resources

For information and advice based on your specific food and nutrition needs and preferences, call 8-1-1 and ask to speak to a HealthLink BC dietitian.

For additional information, see the following resources:

• HealthLink BC www.healthlinkbc.ca – Get medically approved non-emergency health information.