This factsheet is intended to help those affected by atrial fibrillation
understand more about the interaction between warfarin and certain
types of food, to help patients maintain a stable INR level.
Many people with atrial fibrillation may and
that warfarin therapy is recommended to thin the blood and reduce
their risk of stroke.
Warfarin is a very affective medication. However,
it does require regular monitoring to assess how thin it makes
the blood. It works by interfering with how the liver uses the
vitamin K taken in our diet.
Warfarin’s affectiveness is thus affected
by the amount of vitamin K in the diet. If the diet is reasonably
consistent, then the amount of vitamin K in your diet will be
matched by the warfarin dose.
If your diet contains foods rich in vitamin K,
there is no need to change your diet or restrict these foods from
normal levels of consumption.
If you wish to make a more sustained change to
your diet, such as eating green leafy vegetables due to their
rich calcium content, you should discuss this with your anti-coagulation
clinic or your doctor, as they may wish to monitor your blood
a little more frequently to ensure the warfarin continues to work
If you change your diet to contain foods that
are richer in vitamin K then you will and you require more warfarin.
If the diet changes to contain more foods that are low in vitamin
K then your warfarin dose may need to be reduced.
A simple rule is that leafy green vegetables
tend to be rich in vitamin K and root vegetables, fruits and cereals
tend to be low in vitamin K.
It is always best to discuss your dietary needs
with a qualified nutritionist or medical professional.
Cranberries can affect warfarin in several different ways, and
not just due to the vitamin K content.
If you are going to start consuming cranberries
or cranberry juice on a regular basis you should let your warfarin
clinic know because your warfarin dose may need adjusting. In
some instances cranberry juice has been reported to increase your
chance of bleeding. Whilst taking Warfarin you are advised to
avoid cranberry juice.