Tag: anticoagulants

Broccoli and Spinach are Not Likely to Affect INR Blood Test

Claus Hancke

December 10, 2004

Promising Dutch study of Vitamin K. The somewhat cryptic headline is probably nonsense to most people, but nevertheless has great importance to all those taking blood-thinning (anticoagulating) medicines such as Marevan (Warfarin) and who are doing the regular blood test control, called INR.

If you are undergoing treatment with anticoagulant drugs such as Marevan, you should regularly be tested with a blood test called INR.

This blood test is designed to estimate if the dose you receive is correct, but it should also prevent overdosing in which the blood would get “too thin”. This condition is dangerous and can result in internal bleeding.

12 healthy volunteers were included in a study in which they were given a correct dosage of anticoagulants for 13 weeks and adjusted to a maintenance dose with a constant and stable INR value that would prevent them from forming blood clots.

Then, they were given increasingly large daily doses of vitamin K from 50 mcg. to 500 mcg. during the course of one week. Not until the dose reached 150 mcg. of vitamin K a day taken as a dietary supplement, was any effect on INR observed. Even at this dose, INR was only affected in 3 out of the 12 trial subjects.

When the trial subjects were given food that is particularly rich in vitamin K, i.e. broccoli and spinach, there was no clinically relevant effect on INR because the effect was so transient, and the authors suggest that the reason might be a poor bioavailability of the vegetables. This may be surprising, as kale, spinach, and broccoli can contain up to 400 mcg. of vitamin K per 100 g.

Doses of 100 mcg. vitamin K as an easily absorbable dietary supplement had no effect on INR.

If this study on healthy, young trial subjects can be repeated with the same result on patients with a predisposition to forming blood clots, it would make life significantly easier on a great number of people who every day stare in despair at the long list of foods containing vitamin K that they are not allowed to eat while taking Marevan.

By: Vitality Council

Reference:
Schurgers LJ, Shearer MJ, et al: Effect of Vitamin K Intake on the Stability of Oral Anticoagulant Treatment. Dose-Response Relationships in Healthy Subjects. Blood 2004;104(9):2682-2689.

www.bloodjournal.org
www.iom.dk

Feel Safe to Use Ginkgo biloba

Claus Hancke

June 24, 2004

A large number of people use this natural remedy on account of its ability to improve memory. This ability has been documented in numerous studies, including British ones. According to the press, the WHO is quoted for having warned against a danger of hemorrhage when Ginkgo biloba is consumed together with anticoagulants.

There are reports of two deaths and a number of non-fatal bleedings from a total of 22 countries. The suspicion is that Ginkgo biloba enhances the effect of the anticoagulants.

Anticoagulants themselves involve a serious risk of internal bleedings, and every year, hundreds of people die as a result of taking anticoagulants. Therefore, without a scientific investigation, it is impossible to know whether it is Ginkgo biloba, the anticoagulants, or solely a combination of both that is responsible.

Every year, several hundred people – in Scandinavia alone – die from this inevitable side effect of anticoagulants, but a great many more are saved by it. The fact that some of the people who have suffered a cerebral haemorrhage have used Ginkgo biloba at the same time, in no way proves that the combination is risky.

More than 30 medicaments in general use can either fortify or weaken the effect of anticoagulants. Both situations can be highly dangerous. Examples of medicine that fortify the effect of anticoagulants are sulpha drugs used against cystitis, a number of antibiotics, and common painkillers like aspirin.

Kale, chicory, spinach, and many other vegetables also affect the treatment. That Ginkgo biloba should affect the treatment, however, has been repudiated in the only serious study performed to date. It is of Danish origin and was published in the Danish Weekly Magazine for Medical practitioners last year.

In a double-blind, randomized trial it was established that neither Ginkgo biloba nor co-enzyme Q10 had any influence on the haemorrhagic tendency in the 24 participants who were all being long-term treated with warfarin which is the most commonly used anticoagulant.

Unfortunately, anticoagulants do involve a risk of internal bleedings. This is unevitable. However, there is nothing to indicate that the this risk should be increased by taking Ginkgo biloba. On the contrary; present knowledge indicates the opposite!

Professor Ralph Edwards of the WHO Monitoring Centre in Uppsala, Sweden, feels abused by the press in this matter, as he says:
“We have NOT warned against Ginkgo biloba. There is no news in the statement of the WHO which is only a press release about new guidelines on information regarding dietary supplements and natural medicine. It is not even very likely that Ginkgo biloba should interact with anticoagulants, but it is common sense not to use a vasodilating supplement together with anticoagulants or in relation to an operation.”

By: Vitality Council

Reference:
Ugeskr Laeger. 2003;4;28;165(18):1868-71. [Effect of Coenzyme Q10 and Ginkgo biloba on warfarin dosage in patients on long-term warfarin treatment. A randomized, double-blind, placebo-controlled cross-over trial].

Also see the original press release of the WHO.

www.dadlnet.dk
www.who.int/mediacentre/news/releases/2004/pr44/en
www.iom.dk