Vitamin K for Patients with Blood Clots

Vitamin K supplementation may improve anticoagulation (preventing blood clots) control in patients with unexplained instability of response to the popular anticoagulant, warfarin, a new study suggests.

Researchers from Newcastle University in the UK explained that patients receiving warfarin who have unstable control of anticoagulation have a significantly lower intake of dietary vitamin K compared with their stable counterparts.

Researchers hypothesized that supplementation with oral vitamin K would improve stability in patients with previously unstable control of anticoagulation. In the study, 70 warfarin-treated patients with unstable anticoagulation control were randomly assigned in a double-blinded fashion to receive a daily amount of 150 mug oral vitamin K or placebo by mouth for six months.

Measures of stability of anticoagulation control in the six-month study period were compared with those in the six months immediately prior to it. Researchers found that vitamin K supplementation resulted in a significantly greater decrease in standard deviation of international normalized ratio (INR) compared with placebo and a significantly greater increase in percentage time within target INR range.

Additionally, anticoagulation control improved in 33 of 35 (94 percent) patients receiving vitamin K supplementation; of these, 19 fulfilled the criteria for having stable control of anticoagulation. However, only 24 of 33 (72 percent) patients receiving placebo demonstrated some degree of improvement, with only seven patients fulfilling the criteria for having stable control.

Researchers concluded that concomitant supplementation of vitamin K, perhaps through reducing the relative day-to-day variability in dietary vitamin K intake, may significantly improve anticoagulation control in patients with unexplained instability of response to warfarin.

For more information about vitamin K, please visit Natural Standard’s Foods, Herbs & Supplements database.

Comments

[J. Kathryn Bryan]

If these patients are not getting enough vitamin K, perhaps their diets are poor overall. After a bit of Web searching, I learned that vitamin K is found in most leafy green veggies, wheat bran and dairy products. But if a person’s diet is comprised of meat, potatoes and casseroles, I can imagine that overall nutrition would be poor. To this extent, perhaps vitamin K is but one of many factors influencing a patient’s failure to respond to vitamin K.

I’d imagine that a vitamin-deficient diet may influence the efficacy of many types of drugs. Surely, the usually gross hospital food couldn’t help with that situation.

[Anonymous]

Currently, there are a lot of vitamin K supplements out there on vitamin shelves as well as online. We also get vitamin K, as another poster mentioned, through diet, primarily via intake of green leafy vegetables. It is mportant for patients who are on warfarin or on anticoagulation therapy to have a consistent intake of vitamin K. That can be achieved through proper counseling and education from physicians, pharmacists, nutritionists, etc.

Studies did show that lower overall consumption of vitamin K does have greater fluctuations in INR levels. But again, consistent intake of vitamin K is important, taken at the recommended RDA values. Also, patients should also be cautious of purchasing vitamin K online or at nutrition stores. Some of the vitamin K content exceeds 5000% of RDA values. Thus, patients must always check the label prior to consumption. Monitoring how much vitamin K is taken in from food should be carefully monitored. If someone who is on warfarin therapy and consistently eating a bowl of spinach salad also takes a 200mcg tablet, he/she could potentially be at risk for blood clots.

[Woods]

I usually cook all of my vegetables. If you cook green, leafy vegetables, does it decrease the amount of vitamin K in the food?

[Leah Cohen]

Interesting point that one reader brought up on the effect of cooking foods that contain vitamin K. There is an article available about this: Bolton-Smith, 2000; Br J Nutr. 2000 Apr;83(4):389-99. - calculations supposedly account for the cooking method and changes in water and fat content.

Another article (Homma, 2006; J Nutr Sci Vitaminol (Tokyo). 2006 Oct;52(5):297-301) discusses the effect of a cooking method of natto on plasma Vitamin K levels. Based on this article there seems to be an effect of cooking methods on Vitamin K content.

[D. B. Martin]

I do not understand, nor is it explained in this abstract, why vitamin K has the paradoxical effect of enhancing anticoagulation when it is well established as an important factor in coagulation. Anyone?

[Cady B]

In response to D.B. Martin, vitamin K is a very important factor in coagulation. It is actually the emergency antidote to a warfarin (Coumadin®) overdose. However, it seems that the amount of vitamin K in the diets of these patients was so variable that their warfarin therapy could not adequately control their INR. With varying amounts of vitamin K, a patient will have varying levels of coagulation, thus, requiring varying amounts of warfarin to counteract the process.

Simply, you're a baker trying to make dough, and in order to get the perfect texture, you need the right amounts of water and flour. If each day you add different amounts of flour to the mixture, you will require different amounts of water to create the desired thickness. When applied to the blood in your body, you can imagine the importance of making sure that your blood is not over coagulated (lots of vitamin K or subtherapeutic levels of warfarin, which can lead to blood clots) or overly anticoagulated (low vitamin K or supratherapeutic levels of warfarin).

This study demonstrates the importance of how a generally consistent level of vitamin K in your diet will greatly aid anticoagulation control.

[Ceadda Wilcox]

Well explained Cady B!!! I was confused like D.B. Martin, but I really appreciate your baking analogy! So, looking at all of the posts, does that mean that another solution is for people just to make sure that have the recommended dose of vitamin K in their diets? Or is the supplementation required?

[Kalyn]

For years, vitamin K was advised not to be used with warfarin. I’m a little surprised with this study to use vitamin K supplementation with warfarin. But hey, as long as it works for unstable patients, this is great for them. But their INR should be monitored closely.

[Larry]

In 2001 I had an operation where they removed a good part of my intestines, due to Crohn's disease. They said that I am not able to absorb as much vitamin K as a normal person can. If I am taking warfarin for AFib, would eating more spinach help or hurt me? I guess something called an INR reading at the hospital said I was a 2.7, not sure what that means, but the doc said it was good.

[MV]

This study shows how a simple increase in vitamin K in the diet can drastically impact someone with anticoagulation problems. I feel as though vitamin K is very easy to get from a diet that includes lots of green leafy vegetables. I am uncertain as to whether patients will have to take vitamin K supplements to receive the necessary dose to reverse anticoagulation.

[Emily P.]

I’d be curious to know the amount of leafy greens that are needed to achieve the same effects of this supplement?

[Paul]

This is sort of bizarre, but makes a ton of sense as well. Warfarin acts by keeping vitamin K from working, which then leads to less clotting ability of platelets. As long as you have the same amount of vitamin K every day, then everything will be good with the warfarin. Getting an INR to goal of 2-3 for most patients on warfarin can be really tricky, especially since warfarin stays active in the body for several days. I will definitely keep this study in mind when I talk to patients on warfarin, especially if they have trouble maintaining their goal INR.

[P.K.]

I have thrombocytosis. My platlet count pushes a million ... blood clots are the fear. I take a baby aspirin, a CoQ10 (50mg), fish oil, and a Centrum Silver (I'm 65) every day. The latter contains 10mcg Vitamin K (label says 13%). I eat almost NO leafy vegetables. Though I love them, I live alone, and they just don't keep well. I eat tons of tomatoes and carrots - every day. Should I add Vitamin K to my daily tablets - and how much -- would it help prevent blood clots? Or is there another food? I don't drink much milk, but I eat a lot of butter (REAL butter) and cheese (saw dairy products mentioned). Should I maybe add milk and or yogurt? And, like Emily P., I'd be curious to know the amount of green leafy vegetables recommended.

[Debbie]

I have also heard that patients on warfarin who eat a lot of vitamin K-containing food have more stable INR than patients who try to avoid it altogether. I think it'™s because they have more consistent diets with less fluctuations. Another point is that many multivitamins contain different amounts of vitamin K. They can range anywhere from 10mcg up to 80mcg, which could affect patients on warfarin. It has been proved that a change of 25mcg can affect a person'€™s INR. So if you're on warfarin and decide to change your multivitamin, be sure to read the label carefully!