Anti-parasitic effects of Cranberry Extract

Cranberries, a major New England crop, contain an abundant supply of bioactive condensed tannins (CT). 

home_berriesPhoto courtesy of the UMASS Cranberry Station;


One of the most promising findings in the last 15 years in the search for alternative gastrointestinal nematode (GIN) parasite control has been the discovery that the consumption of some forages containing condensed tannins (CT) suppress GIN infection in sheep and goats.  Condensed tannins (CT), also called proanthocyanidins (PAC), are naturally occurring plant compounds that significantly affect the nutritional value of forage by forming complexes with proteins, carbohydrates and minerals.

Cranberries, a major New England crop, contain an abundant supply of bioactive condensed tannins.  Cranberry leaves are a readily available waste product of the harvesting process and contain a higher percentage of the PAC than the fruit, making it an economically attractive source of PAC.

URI Research

URI has been researching the potential of the condensed tannins in cranberry leaves to serve as a natural dewormer (anthelmintic).  The anti-parasitic effect of the cranberry leaf CT extract—PAC and of cranberry leaf powder (CLP) have been evaluated using both in vitro and in vivo methods.  The anti-parasitic properties of PAC have been researched using in vitro experimental Haemonchus contortus (barber pole worm) egg hatch and larval development assays; and of cranberry leaf powder (CLP) using in vivo experimental H. contortus infections in sheep.

The condensed tannins in cranberries may have efficacy as an alternative anti-parasitic for small ruminant producers.  Further research into the amount, form and duration of cranberry extract and dosing methods for optimal anti-parasitic effects is warranted.

Lead URI researcher:

Katherine Petersson, Ph.D. –
Dept. Fisheries, Animal and Veterinary Sciences

Manuscripts of this research are in progress and will be submitted to peer-reviewed journals.

URI presented on-going research at the 93rd and 94th Annual Conferences for Research Workers in Animal Diseases (CRWAD, Chicago, IL), December 2012 and 2013; and at several workshops and meetings conducted for farmers and veterinarians throughout the Northeast region.

This work is supported by funding from the Northeast Sustainable Agriculture Research and Education Program which is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture; and the Rhode Island Agricultural Experiment Station (RI00H-900-INT).  


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