Cranberries have been grown in North America for centuries. Enjoyed for both their taste and their nutritional value, cranberries are thought to be beneficial for the treatment of a variety of symptoms, as well as for the prevention of certain conditions. Specifically, a link has been proposed between cranberry intake and Coumadin, a medication for blood clots. Understanding the history and the nutritive properties of cranberries, as well as Coumadin's mechanism of action, may better define any existing connection between the two.
History of Cranberries in North America
As early as the sixteenth century, cranberries were used by Native Americans for food, medicinal purposes and as a dye for clothing. The first known cultivation of the fruit was in 1816 by Captain Henry Hall of Dennis, Massachusetts. The use of sand in tandem with fresh water and acidic peat soil proved to be an effective means of growing cranberries, and others quickly adopted Captain Hall's method.
Over the next several decades, the market for cranberries slowly increased in the United States; additionally, according to the Cape Cod Cranberry Growers' Association, the international market for cranberries was established in the 1980s. At that time, the demand for cranberries soared worldwide.
Cranberry Juice and Health
As the demand for cranberries increased, other related products also became popular, including cranberry juice. First developed by early American settlers in 1683, cranberry juice is also known to have medicinal value. As early as the 1850s, sailors are reported to have used cranberry juice while at sea to prevent scurvy, or a disease related to Vitamin C deficiency.
Over the years, cranberries or cranberry juice have been used to relieve the symptoms of diarrhea and other gastrointestinal ailments, as well as urinary tract infections. More recently, the question has been raised regarding a possible interaction between cranberries and Coumadin, a medication used for the treatment of blood clots.
Coumadin as Treatment for Blood Clots
According to Medscape, Coumadin (or Warfarin, the generic name for the medication) was first discovered in the 1940s. The medicine was determined to be effective in the prevention and treatment of blood clots, a purpose for which it is still widely used at present. Coumadin prevents the activation of certain clotting factors within the body, thereby thinning blood and reducing the risk for clot formation. While this medication is very effective as prophylaxis against or treatment for blood clots, there are also several possible interactions with foods or other medications that may occur. In recent years, concerns have been raised regarding cranberry juice and its potential for interacting negatively with Coumadin.
Cranberries and Coumadin
Perhaps the greatest concern regarding cranberry intake for patients taking Coumadin is an elevation in INR (or International Normalized Ratio). The INR is used as a measure of how thin a person's blood is. In several case studies published between 2003 and 2006, patients who drank cranberry juice while taking Coumadin had an abnormally high INR level, meaning the blood was dangerously thin. The risk for hemorrhage or even death is elevated if the INR level is too high.
One possible explanation for the interaction between cranberries and Coumadin is the presence of salicylic acid within the fruit. Salicylic acid has antiplatelet properties; in other words, preventing platelet activity increases the potential for bleeding. Combining cranberry juice with Coumadin could therefore potentiate the effect of the medication, resulting in a significantly increased risk for bleeding.
Conclusions
Cranberries are an enjoyable fruit, not only for their taste, but also for their nutritional value. Although cranberries and cranberry juice have been used to treat the symptoms of several illnesses, the link between blood clots and cranberries seems less clear. Recently, studies have shown an increase in bleeding risk with cranberry juice intake for patients taking Coumadin, a medicine for blood clot prevention or treatment. As a result, current recommendations require patients taking Coumadin for the treatment or prevention of blood clots to limit or eliminate altogether the intake of cranberries and cranberry juice.
