Warfarin and Vitamin K Guide
This article is a guide for warfarin-treated patients who also take vitamin K. In recent times, people taking blood-thinning medications have been told to limit or moderate their vitamin K intake. However, current research have revealed that limiting vitamin K intake for patients taking blood-thinning medication is not the best advice.
According to these recent expects, people taking warfarin are encouraged to increase their intake of vitamin K, not decrease it.
Before now, patients taking blood-thinning drugs such as warfarin are told by doctors to reduce their intake of vitamin K. This is because doctors believed that taking too much of this vitamin can decrease the drug’s effectiveness.
This is due to the belief that the vitamin interacts with blood clotting process and can interfere with the drug’s blood-thinning properties.
But what if this advice is wrong?
A new clinical trial suggests that people taking warfarin or other blood-thinning drugs should actually be told to increase the amount of vitamin K they consume.
This clinical trial is the first randomized controlled trial testing that covers how people taking warfarin responded to dietary changes aimed at increasing vitamin K intake.
The study included nearly 50 patients with a history of anticoagulation instability, which is an inability to maintain healthy levels of blood clotting.
Half of the participants were provided dietary counseling sessions and cooking lessons that offered general nutritional advice.
Green and leafy vegetables such as spinach, broccoli and lettuce are rich in vitamin K. Also, foods such as kiwi, asparagus and soybeans are good sources of vitamin K.
Six months after the study began, 50 percent of the participants who were taught to increase their vitamin K intake were all able to maintain stable anticoagulation levels.
Only 20 percent of those receiving general nutritional counseling achieved a similar improvement.
A lead study from the Université de Montréal and the Montreal Heart Institute Research Centre, said the findings suggest patients on warfarin would significantly benefit from consuming at least 90 micrograms of vitamin K per day for women and 120 micrograms per day for men.
What is more?
Warfarin is typically used to prevent blood clots from forming. It is also often used for medical conditions such as an irregular heartbeat, clots in the veins of the body called “deep-vein thrombosis or pulmonary embolism”, and after a heart valve replacement.
Williams explained the reasoning behind the current recommendations.
“Vitamin K is part of the complex process needed for the body to make clots, and warfarin blocks this process,” she said. “So eating too many foods rich in vitamin K is believed to cause warfarin to become less effective and cause more clotting in the body.”
Warfarin-Treated patient should consistently take vitamin K
Warfarin-treated patients would benefit from increasing their daily vitamin K intake.
According to experts, given the direct interaction between dietary vitamin K and the action of the drug, it is important that [higher] daily vitamin K intakes be as consistent as possible.
Our hope is that healthcare professionals will stop advising warfarin-treated patients to avoid green vegetables which is a rich source of vitamin K.
Clinically, this may prevent patients on warfarin from having too many highs and lows on their INRs. INR is an acronym for “International Normalized Ratio”. It is a blood test used to monitor how thick or thin the blood is. This could give more consistency to the patient’s blood clotting ability.
It is however cautioned that while the information in this trial is thought-provoking for physicians, larger studies will need to be conducted before significant changes can be made in patient care.
Precautions with warfarin
Apart from the findings of this clinical trial, there are other medications and vitamins that can affect how warfarin works. These include:
#1. prescription medications, such as the common antibiotics azithromycin and ciprofloxacin
#3. vitamin preparations containing large amounts of vitamin E or vitamin C
#4. Alcohol consumption may also influence the way your body metabolizes warfarin.
The American Heart Association (AHA) recommends that men shouldn’t have more than one or two drinks per day and women should limit themselves to about one drink per day when taking warfarin.
Warfarin side effects
Like almost any prescription drug, warfarin users may experience side effects.
Symptoms that indicate you should call your doctor include:
#2. bruising easily
#3. “purple toe syndrome” a type of skin destruction (necrosis)
For patients who have been told they need to take a blood thinner and are concerned about these issues, there are newer medications available called direct-acting oral anticoagulants (DOACs).
This class of drugs includes apixaban, rivaroxaban, and others.
DOACs are shorter acting than warfarin. They also don’t require blood test monitoring for bleeding and clotting risk. Also, they have fewer drug and food interactions than warfarin.
What foods and drinks should be avoided when taking Warfarin?
Although we encourage you to take green vegetables, however, where there is high risk of bleeding problems, certain foods and drinks which can increase the effect of warfarin, leading to bleeding problems should be avoided.
Avoid or consume only small amounts of these highly risky drinks when taking warfarin. These drinks are Cranberry juice and Alcohol.
Also foods that must be avoided when taking warfarin are:
#3. Brussels sprouts.
#5. Mustard greens.
Can warfarin cause vitamin K deficiency and low bone mass?
It is reasonable that a potential role of vitamin K in bone health could be elucidated by study of patients receiving oral anticoagulants that act to produce vitamin K deficiency. However, some reports find K deficiency induced by warfarin (W) anticoagulation to be associated with low bone mass.
Warfarin is a drug prescribed to patients at risk of dangerous blood clots. It can slow the body’s production of clotting factors, which are produced using vitamin K. New research finds levels of vitamin K in a person’s diet can improve, rather than impede the effects of warfarin. However, there are other vitamins and medications that will affect people taking warfarin. So, care must be taken when using them.
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- A Patient Guide to taking Warfarin. Heart.org https://www.heart.org/en/health-topics/arrhythmia/prevention–treatment-of-arrhythmia/a-patients-guide-to-taking-warfarin
- Event Scribe. Université de Montréal and the Montreal Heart Institute Research Centre. https://www.eventscribe.com/2019/ASN/fsPopup.asp?Mode=presInfo&PresentationID=545052