2 results
The efficacy and safety of comfrey
- Felix Stickel, Helmut K Seitz
-
- Journal:
- Public Health Nutrition / Volume 3 / Issue 4a / December 2000
- Published online by Cambridge University Press:
- 02 January 2007, pp. 501-508
-
- Article
-
- You have access Access
- Export citation
-
Herbal medication has gathered increasing recognition in recent years with regard to both treatment options and health hazards. Pyrrolizidine alkaloids have been associated with substantial toxicity after their ingestion as tea and in the setting of contaminated cereals have led to endemic outbreaks in Jamaica, India and Afghanistan. In Western Europe, comfrey has been applied for inflammatory disorders such as arthritis, thrombophlebitis and gout and as a treatment for diarrhoea. Only recently was the use of comfrey leaves recognized as a substantial health hazard with hepatic toxicity in humans and carcinogenic potential in rodents. These effects are most likely due to various hepatotoxic pyrrolizidine alkaloids such as lasiocarpine and symphytine, and their related N-oxides. The mechanisms by which toxicity and mutagenicity are conveyed are still not fully understood, but seem to be mediated through a toxic mechanism related to the biotransformation of alkaloids by hepatic microsomal enzymes. This produces highly reactive pyrroles which act as powerful alkylating agents. The main liver injury caused by comfrey (Symphytum officinale) is veno-occlusive disease, a non-thrombotic obliteration of small hepatic veins leading to cirrhosis and eventually liver failure. Patients may present with either acute or chronic clinical signs with portal hypertension, hepatomegaly and abdominal pain as the main features.
Therapeutic approaches include avoiding intake and, if hepatic failure is imminent, liver transplantation. In view of the known serious hazards and the ban on distributing comfrey in Germany and Canada, it is difficult to understand why comfrey is still freely available in the United States.
Hepatotoxicity of botanicals†
- Felix Stickel, Gerlinde Egerer, Helmut Karl Seitz
-
- Journal:
- Public Health Nutrition / Volume 3 / Issue 2 / June 2000
- Published online by Cambridge University Press:
- 02 January 2007, pp. 113-124
-
- Article
-
- You have access Access
- Export citation
-
Objective
Hepatic impairment resulting from the use of conventional drugs is widely acknowledged, but there is less awareness of the potential hepatotoxicity of herbal preparations and other botanicals, many of which are believed to be harmless and are commonly used for self-medication without supervision. The aim of this paper is to examine the evidence for hepatotoxicity of botanicals and draw conclusions regarding their pathology, safety and applications.
DesignCurrent literature on the hepatotoxicity of herbal drugs and other botanicals is reviewed. The aetiology, clinical picture and treatment of mushroom (Amanita) poisoning are described.
ResultsHepatotoxic effects have been reported for some Chinese herbal medicines (such as Jin Bu Huan, Ma-Huang and Sho-saiko-to), pyrrolizidine alkaloid-containing plants, germander (Teucrium chamaedrys), chaparral (Larrea tridentata), Atractylis gummifera, Callilepsis laureola, and others. The frequency with which botanicals cause hepatic damage is unclear. There is a lack of controlled treatment trials and the few studies published to date do not clarify the incidence of adverse effects. Many plant products do not seem to lead to toxic effects in everyone taking them, and they commonly lack a strict dose-dependency. For some products, such as Sho-saiko-to, the picture is confused further by demonstrations of hepatoprotective properties for some components. Mushroom poisoning is mostly due to the accidental consumption of Amanita species. Treatment with silymarin, thioctic acid, penicillin and liver transplantation have been shown to be effective but require early diagnosis.
ConclusionsSevere liver injury, including acute and chronic abnormalities and even cirrhotic transformation and liver failure, has been described after the ingestion of a wide range of herbal products and other botanical ingredients, such as mushrooms. It is concluded that in certain situations herbal products may be just as harmful as conventional drugs.