Milk thistle (Silybum marianum) is an extensively researched plant, rich in flavonoids and commonly used to treat various liver diseases.1
The active component of milk this-
tle is a lipophilic extract composed of three flavonolignan isomers—silybin, silydianin, and silychristin, which are collectively known as silymarin, as explained in Figure 1. The terms milk thistle and silymarin are often used interchangeably; silymarin is used to refer to all three flavonolignan isomers making up the milk thistle.2,3
Silymarin is concentrated
in the fruit and seeds of the milk thistle plant and works as an antioxidant capable of reducing free radical by-products of some chemical reactions.4
Few well-designed clin-
ical studies conducted to investigate the effects of milk thistle on liver diseases such as chronic hepatitis C have reported any benefit.2
A recent review of 14 randomized clin-
ical trials evaluated the effectiveness of milk thistle in the treatment of liver diseases.5 Researchers found that there was no reduction in mortality and no improvement in
Figure 1 Milk thistle compounds HO O HO O O HO O OH silybin (silybin A; silibinin; silibinin A) O HO HO O O H silydianin O O HO HO HO O OH silychristin (silychristin A; silichristin; silichristin A) O OH OH H HO O OH O OH O OH