Cranberry and Warfarin Don’t Mix
November 22, 2009
Jacob Schor ND FABNO
Most people don't want to meddle and ask questions about their dinner guests medical conditions. Perhaps we should rethink this attitude, at least when it comes to warfarin. Warfarin, aka Coumaden, aka rat poison, is the most commonly prescribed prescription blood thinner. Lots of people are taking it. These people need to be careful at Thanksgiving time. It is because that's when we eat cranberries. And we eat a lot of cranberries these days.
Domestic cranberry production was about 5 million hundred pound barrels back in 1997. Current production has increased to 6.9 million barrels in 2007.
A strong cautionary warning appeared in the British Journal of Pharmacology in August 2008. Cranberries interact with the drug warfarin, commonly sold as Coumaden. This drug is an anticoagulant and used to prevent blood clotting. It is a serious drug to take and requires routine monitoring to keep drug levels in certain specified ranges.
Abdul Mohammed and his colleagues on the Pharmacy faculty at the University of Sidney in Australia tested the effect of cranberries on warfarin in healthy volunteers. What they found was disturbing. Cranberries made the drug action stronger, about 30% stronger.
This would be ok if people taking warfarin ate the same amount of cranberries year round. Then they could get away with taking almost a third less of the drug. It doesn’t work that way though. Cranberry consumption is seasonal. The majority of the crop will be eaten between Thanksgiving and Christmas. People taking warfarin should be hesitant with cranberries, avoiding second helpings if possible. As far as drinking cranberry juice, either drink it regularly, the same amount each day, or avoid it. The later suggestion makes the most sense.