Chitosan is a polysaccharide with a number of commercial and possible biomedical uses. Purified quantities of chitosans are available for biomedical applications.
Researchers from Taipei Veterans General Hospital and National Yang-Ming University in Taiwan reported a case in which the anticoagulation (blood thinning) effect of warfarin appeared to have been increased by chitosan, probably due to interference with the absorption of vitamin K.
The study authors reported that chitosan is a positively charged polymer that binds to the negatively charged lipids and bile acids in the gastrointestinal tract. It can affect the absorption of vitamin A, vitamin D, vitamin E and vitamin K. Therefore, the anticoagulation effect of warfarin may be enhanced by chitosan through this mechanism.
The study authors concluded that although not previously reported, healthcare professionals should be aware of the potential interaction between chitosan and warfarin.
For more information about herb-drug interactions, please visit Natural Standard's Interactions database.