by G. Lee

Created on: September 28, 2007

Milk thistle (scientific name - Silybum marianum) is a thistle native to the Mediterranean region. The seeds are used medicinally, although the stalk and young leaves have been eaten as a salad vegetable. Milk thistle preparations have been used for over 2000 years in European medicine to treat liver and biliary diseases. Basically, milk thistle contains 1.5 to 3% of flavanolignans including silybin, silychristin, silydianin and 2,3-dehydro derivatives (collectively known as silymarin), as well as fixed oils, flavanoids, taxifolin and steroids.

Milk thistle is often used to treat liver damage. It is able to do so because the silymarin component of milk thistle protects against paracetamol-induced lipid peroxidation and liver damage. When paracetamol and silymarin are given concurrently, lipid peroxidation and liver enzyme levels remained within control levels, in contrast to when paracetamol was given alone.

In addition, milk thistle is also clinically proven to reduce the mortality of patients with alcoholic and non-alcoholic cirrhosis, with effects more pronounced in alcoholic cirrhosis. The review of the study showed that prothrombin time was improved and liver transaminase levels were lower in patients with alcoholic liver disease treated with silymarin. It was concluded from the study that silymarin may be of use as an adjuvant in the therapy of alcoholic liver disease.

Besides, a study using milk thistle in patients with chronic active hepatitis (CAH) shown that there was a statistically significant reduction in AST, ALT, gamma-GT and total bilirubin levels, all of which increases the risk for hepatitis. The results show that the treatment may reduce hepatocellular necrosis and/or increases membrane permeability in patients affected by CAH.

There is experimental evidence that silymarin-induced protection of liver function may be of benefit with regards to liver regulation of plasma lipoproteins. Some data suggests that silymarin could have a direct effect on liver cholesterol by inhibiting cholesterol biosynthesis.

Furthermore, milk thistle can be used as an antioxidant as well. Silymarin scavenges pro-oxidant free radicals and increase glutathione production in tissues of the liver, intestines and stomach. Increases in superoxide dismutase (SOD) activity in patients with liver disease has also been reported.

Milk thistle also has cholagogic and choleretic activity. Silymarin may increase bile salt biliary excretion by stimulating the production of hepatoprotective bile salts, for instance ursodeoxycholate and beta-muricholate.

Thus, these combined effects help to explain milk thistle's traditional uses as a hepatoprotective and hepatotrophorestorative herb. It is a relatively safe drug to use with only rare events of gastrointestinal upsets and mild laxative effects.

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