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Grape Seed Extract — a potential preventative for dangerous blood clots?

Grape seeds contain a variety of interesting compounds with pharmacological properties. Among these are a class of compounds known as “proanthocyanidins”*. Proanthocyanidins are found not only in grape seeds, but also in the bark of pine trees, an extract of which is commercially marketed as “Pycnogenol®”.

Since the 1990s it has been known that Pycnogenol supplementation can prevent deep-vein thrombosis — the formation of blood clots in deep veins. These are the kind of clots that can break loose and get carried to other parts of the body, causing fatal strokes or lung damage. Travelers who sit for long periods in airplanes or motor vehicles are especially prone to getting such thromboses in their legs. Some physicians have drawn the obvious inference that Pycnogenol supplements may offer protection from this danger, and have been advising their patients to take Pycnogenol or some other source of proanthocyanidins (such as grape seed extract) before travelling. But until now there has been no direct proof that such supplements actually reduce the incidence of deep-vein thrombosis in travelers.

Now the evidence is in: a recent clinical study has shown a significantly decreased incidence of deep-vein thrombosis in travelers taking Pycnogenol compared to those taking a placebo.

Link to a news article:

Link to published study:

* Pronuciation: proanthocyanidins pro-ANN-tho-sigh-ANN-ih-dinz

The anti-thrombotic activity of Pycnogenol has been known about since the 1990s, and applies not only to travelers but to all of us. Smokers are particularly at risk for dangerous blood clots, as are people who take drugs with clot-promoting side effects (such as estrogens).

Grapes are a good source of the proanthocyanidins that are considered to be the active substances in Pycnogenol. And grape seed extract supplies these proanthocyanidins in a concentrated form.

Link to 2000 study on Pycnogenol and blood clotting in smokers:

Link to brief history of the discovery of Pycnogenol:

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