Silymarin (Milk thistle)
Milk thistle (Silybum marianum) has been used since ancient times to treat a variety of liver and gallbladder diseases. Modern research has shown that a group of flavonolignans, collectively referred to as silymarin, have been shown to act as hepatoprotectants against a diverse range of toxins including acetaminophen, carbon tetrachloride, mushroom poisoning (phalloidin), radiation, iron overload, phenyl hydrazine, alcohol, cold ischemia and thiocetamide in animal studies (Jacobs, 2002). Silymarin works as an antioxidant by reducing free radical production, protects against lipid peroxidation, stabilizes cell membranes, has anti-fibrotic properties, and inhibits NF-kB activation with favorable immunomodulatory effects (Dehmlow, 1996; Saliou, 1998; Manna, 1999; Hanje, 2006).
A recent systematic review and meta-analysis by Saller, et al concluded that the use of silymarin is reasonable in Amanita phalloides poisoning, alcoholic liver disease (as an addition to abstinence) and Child’s A cirrhosis (Saller, 2008). Large controlled trials of silymarin have been performed to evaluate its effects upon liver function in chronic liver disease, with variable results, probably due to low-quality clinical trials (Hanje, 2006).
In the United States, silymarin is one of the most commonly used alternative medical agents in the treatment of liver disease, in part because of its good safety profile. Well-designed, multicenter RCTs of silymarin are required to prove its effectiveness in chronic liver disease, and NIH-sponsored trials are ongoing.