Viral Hepatitis and Milk Thistle

Native to Europe, milk thistle has a long history of use as both a food and a medicine. In the 1960s, German researchers were sufficiently impressed with the history and clinical effectiveness of milk thistle to begin examining it for active constituents. In 1986, Germany's Commission E approved an oral extract of milk thistle as a treatment for liver disease. Milk thistle has since shown some scientific promise as a treatment for both acute and chronic viral hepatitis.

Milk thistle may help treat both acute and chronic viral hepatitis, as well as alcoholic hepatitis. Standardized milk thistle extract includes many active chemicals. The most active of these chemicals is commonly known as silibinin. Silibinin is believed to work by displacing toxins trying to bind to the liver as well as by causing the liver to regenerate more quickly.⁹ It may also act as an antioxidant and also stabilize liver cell membranes.^10,11

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A 21-day, double-blind, placebo-controlled study of 57 people with acute viral hepatitis found significant improvements in the group receiving milk thistle.²⁰ A 35-day study of 151 individuals thought to have acute hepatitis found no benefit with milk thistle, but this study has been criticized for failing to document that the participants actually had acute hepatitis.^21,22

Inconsistent evidence exists regarding whether milk thistle is helpful for chronic viral hepatitis B or C.^{17-19,44,46,51} The herb does not appear to affect levels of virus in the body, but might help protect the liver from damage and improve some symptoms.

The standard dosage of milk thistle is 200 mg 2 to 3 times a day of an extract standardized to contain 70% silymarin.

There is some evidence that silymarin bound to phosphatidylcholine may be better absorbed.^34,35 This form should be taken at a dosage of 100 mg to 200 mg twice a day.

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Safety Issues

Milk thistle is believed to possess very little toxicity. Animal studies have not shown any negative effects even when high doses were administered over a long period of time. ¹ A study of 2,637 participants reported in 1992 showed a low incidence of side effects, limited mainly to mild gastrointestinal disturbance. ² However, on rare occasions severe abdominal discomfort may occur. ³ On the basis of its extensive use as a food, milk thistle is believed to be safe for pregnant or nursing women and researchers have enrolled pregnant women in studies. ⁴ However, safety in young children, pregnant or nursing women, and individuals with severe renal disease has not been formally established.

No drug interactions are known. However, one report has noted that silibinin can inhibit a bacterial enzyme called beta-glucuronidase, which plays a role in the activity of certain drugs, such as oral contraceptives. ⁵ This could theoretically reduce their effectiveness.

Interactions You Should Know About

If you are taking:

• Medications that could damage the liver, such as acetaminophen, phenytoin (Dilantin), alcohol, and phenothiazines: Milk thistle might be protective for some of these drugs.

• Oral contraceptives : Milk thistle might reduce their effectiveness.

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