CHAPEL HILL -- Comfrey, an herb widely available in U.S. health food stores and sometimes used as a laxative or anti-inflammatory medication, can cause severe liver damage and should be banned, according to scientists speaking Thursday (March 2) at the University of North Carolina at Chapel Hill. Pyrrolizidine alkaloids present in the plant have been linked to poisoning after people consumed them in tea and contaminated cereals.
"Therapeutic approaches include avoiding intake of comfrey and, once severe liver damage has emerged, liver transplantation," said Dr. Felix Stickel of the University of Erlangen and Salem Medical Center in Heidelberg, Germany. "Taking this into consideration, it is difficult to understand why comfrey is banned in Germany and Canada but is still freely available in the United States."
Mechanisms by which comfrey can ruin the liver are unclear, but the main injury appears to be destruction of small veins leading to cirrhosis and eventually liver failure, he said. Patients may display either acute or chronic symptoms, including abdominal pain, high blood pressure in the organ's portal vein and liver enlargement.
Stickel was one of the presenters at the first international scientific conference on "The Efficacy and Safety of Medicinal Herbs," sponsored by UNC-CH's Institute of Nutrition and schools of public health and medicine and other organizations. Speakers from Canada, England, Germany and the United States discussed what's been confirmed about eight of the world's most widely used herbs -- garlic, ginseng, Ginko biloba, comfrey, saw palmetto, feverfew, echinacea and St. John's wort.
"It's essential that health professionals know what we know about these products and what's still speculation, so that they can give informed advice," said Dr. Lenore Arab, professor of epidemiology and nutrition at UNC-CH. "Right now, the public has stopped asking, and even if people were asking, most health professionals do not feel that
Contact: David Williamson
University of North Carolina at Chapel Hill