Milk Thistle

Claims, Benefits: Protects the liver; treats liver disease.

Bottom Line: It may have potential as a drug, but studies have mostly been brief or flawed. Nobody knows exactly what milk thistle can do.

Full Article, Wellness Letter, December 2000

Ask the Expert

Q: Should I take milk thistle to protect my liver?
L.P., VIA THE INTERNET

A: There's no evidence that milk thistle has any benefits for healthy people. The name of this plant arises from the white markings on the leaves, and its traditional use by nursing mothers to promote lactation (we don't recommend it for that purpose).

A close relative of the artichoke, milk thistle has been used medicinally since ancient times and is today often used in Europe for treating liver diseases, such as cirrhosis and hepatitis. It may have potential as a drug, but studies of milk thistle extract as a treatment for cirrhosis and hepatitis have mostly been brief or flawed.

The chemistry of milk thistle—unlike that of most herbs—is well understood. The seedlike fruit of the plant contains about 100 compounds, including a complex called silymarin, which in turn contains silybin, which acts as an antioxidant and may help block or remove harmful substances from the liver. However, according to Varro Tyler, the well-known expert on herbs, it's difficult for the body to absorb silymarin.

Unlike most herbs, milk thistle can be bought in standardized doses. The problem is that nobody knows exactly what milk thistle can do.
Few side effects have been reported, except for diarrhea, and also sometimes a drop in blood sugar, which may be of concern to people with diabetes. The active ingredient does not dissolve in water, so milk thistle teas are not effective.

UC Berkeley Wellness Letter, December 2000