Overview
Milk Thistle (Silybum marianum, 肝宝) is the most commonly used herb in USA and in Europe to maintain a healthy liver function. Research has shown that standardized Milk Thistle extract provides antioxidant activity. It helps protect liver from cell damages caused by alcohol and toxic chemicals and improve symptoms of chronic liver disease or cirrrhosis.† It has few side effects.

Milk Thistle Health Benefits
Europeans have used Milk Thistle to treat liver disorders for over 2000 years. The application has been largely confirmed by modern studies in laboratories, in animals, and in human clinical trials.

How does Milk Thistle protect the liver? Liver is the organ where toxic substances from either food intake or metablism are accumulated and then detoxified. Silymarin is found to strengthen cell membranes and thus may prevent toxic chemicals from entering the cells; Silymarin also stimulates the liver detoxification pathways; Silymarin is a potent antioxidant and able to neutralize many free radicals; Silymarin can prevent cell death and tumor formation caused by UV irradiation.

In animal studies, after animals were fed with silymarin and then exposed to toxins, they showed much less severe toxic reactions, higher survival rates, lower tumor incidence. Silymarin also reduces kidney toxicity associated with chemotherapy in rats without compromising the efficacy of chemotherapy.¹

Milk Thistle is further evaluated in human clinical trials in patients with hepatitis, cirrhosis, or chronic liver disease. Although the results remain controversial among trials, many trials found that silymarin can lower the levels of liver enzymes SGOT (serum glutamic-oxaloacetic transaminase) and SGPT (serum glutamate pyruvate transaminase). As these enzymes are indicative of liver malfunction, their reduction suggests an improved liver function.² Most significantly, in a randomized, double blind, placebo-controlled trial of patients with cirrhosis (some due to alcohol) over 4 years, patients treated with silymarin showed much improved survival rate than the placebo treated patients (58% vs. 39%). ³

Active Ingredients
Research on Milk Thistle mostly uses standardized extracts made from its seeds. The standardized extracts are concentrated 40-70 times and typically contains 70-80% silymarin, the active ingredient of Milk Thistle. Silymarin is a flavonoid compound consisting of silibinin, isosilibinin, silychristin, and silydianin.

Dose and Duration
In the Milk Thistle clinical trials, patients typically took 420 mg silymarin (that is 175 mg x 3 standardized extract with 80% silymarin) per day, divided in 3 times. The trials commonly last from several months to 4 years.

Milk Thistle Side Effects
Side effects are rare in the Milk Thistle clinical trials.

Milk Thistle Drug Interaction
None is known.

Reference
1. Bokemeyer C, Fels LM, Dunn T, Voigt W, Gaedeke J, Schmoll HJ, Stolte H, Lentzen H. Silibinin protects against cisplatin-induced nephrotoxicity without compromising cisplatin or ifosfamide anti-tumour activity. Br J Cancer. 1996 Dec;74(12):2036-41.
2. http://www.nci.nih.gov/cancertopics/pdq/cam/milkthistle/HealthProfessional/page9/print
3. Ferenci P, Dragosics B, Dittrich H, Frank H, Benda L, Lochs H, Meryn S, Base W, Schneider B. Randomized controlled trial of silymarin treatment in patients with cirrhosis of the liver. J Hepatol. 1989 Jul;9(1):105-13.

by X. Li, Ph. D. (credential)