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HealthInfo Waitaha Canterbury

Food choices & warfarin

Ngā kōwhiringa kai me warfarin

There is no special diet to follow if you're taking warfarin. But there are certain foods and drinks that can affect how your warfarin works.

Keep your intake of vitamin K the same each day

Vitamin K has the opposite effect of warfarin and may cause your blood to clot more quickly.

It's found in some foods and nutrition supplements.

If you're taking warfarin, continue to eat foods that are rich in vitamin K but try to eat the same amount of vitamin K every day. Warfarin works best if you avoid suddenly eating a lot more or a lot less vitamin K-rich foods than usual.

Vitamin K-rich foods include:

Aim to have at least five servings of vegetables every day:

Keep your intake of canola, olive, and soybean oil low

These oils contain small amounts of vitamin K.

Limit your alcohol intake

Having too much alcohol can affect how your warfarin works. If you drink alcohol, limit it to:

For more advice about alcohol and standard drink equivalents, see Reducing your risks from drinking alcohol.

Limit cranberry juice, grapefruit juice and green tea

Having too much cranberry juice, grapefruit juice or green tea can affect the way warfarin works. Limit yourself to a total of no more than one cup (250 ml) of these drinks per day.

Talk to your pharmacist or general practice team if you take warfarin and want to take cranberry supplements.

Talk to your doctor before starting or stopping any nutrition supplements or herbal medicines

Many nutrition supplements, such as vitamins and minerals and dried or powdered vegetable supplements (such as Super Greens or Super Foods) contain vitamin K. Some do not, but they may still affect the way warfarin works.

Talk to your general practice team:


If you know your recent food or alcohol intake has changed significantly, the safest thing is to have an extra INR blood test to check whether your warfarin has been affected.

Written by HealthInfo clinical advisers. Last reviewed February 2023.


See also:

Warfarin monitoring

Page reference: 261113

Review key: HIBTM-167196