Milk thistle

Other common names: Mary’s thistle
Latin name: Silybum marianum (L.) Gaertn. [Asteraceae]
Plant part: Seed


Milk thistle is native to southern Europe and northern Africa. The
plant part that is used medicinally is the ripe fruit (seed) with the outer
covering (pappus) removed. The seed contains about 2 to 3 percent of
the active constituent silymarin, a mixture of four isomers: silybin
(also spelled silybinin) (50 percent), isosilybinin, silydianin, and
silychristin. Studies conducted on silymarin have shown that it promotes
liver-tissue regeneration, and has antitoxic effects on the liver
(Schulz, Hänsel, and Tyler, 2001).

Legalon® is manufactured in Germany by Madaus AG. Legalon
contains a standardized extract of milk thistle seeds that is characterized
as containing 80 percent silymarin (140 mg silymarin per 173 to
186.7 mg extract). Legalon was previously distributed in the United
States by Nature’sWay Products, Inc., under the name of Thisilyn®.
Silipide, produced by Inverni della Beffa in Italy, contains a milk
thistle seed extract, IdB 1016, also known as Siliphos®, that is manufactured
by Indena S.p.A. Siliphos is a complex of silybin combined
with phosphatidylcholine containing 29.7 to 36.3 percent silybin. An
initial pilot study was conducted on a product with a molar ratio of
silybin to phosphatidylcholine of 1:1 (Buzzelli et. al., 1993). The current
product is manufactured with a ratio of silybin to phosphatidylcholine
of 1:2. Siliphos is sold in the United States under the
names UltraThistle™ and Maximum Milk Thistle™ by NaturalWellness.
Silimarina® is manufactured in Romania by Biofarm. Each 700
mg tablet contains the equivalent of 35 mg silybin. The clinical study
report claims that Silimarina is a copy of Legalon.
One trial was conducted on a product simply described as silymarin,
using a dose of 800 mg daily. No further description was available.


Milk thistle preparations have been tested for their ability to treat
symptoms of liver disease caused by alcohol, other toxins, or viral infections.
The major liver diseases are hepatitis, cirrhosis, and dysfunctions
related to bile secretion. Hepatitis is characterized as an inflammation
of the liver that can be present with or without cirrhosis.
Forms of viral hepatitis include hepatitis A, B, and C. Cirrhosis is a
state in which the tissue in the liver breaks down, becoming fatty and
fibrous. Liver disease can be acute (short term) or chronic (long term)
leading to cirrhosis and eventually to liver failure (Morazzoni and
Bombardelli, 1995; Habib, Bond, and Heuman, 2001).

 

The clinical symptoms of liver disease are jaundice (yellowing of
the skin), enlarged liver, ascites (pooling of fluid in the abdominal
cavity), and encephalopathy (breakdown of brain tissue leading to
impaired consciousness). Liver disease is characterized by a buildup
of liver enzymes in the blood. These enzymes include aspartate
aminotransferase (AST, also known as glutamic oxalacetic transaminase
or GOT), alanine aminotransferase (ALT, also know as
glutamic pyruvate transaminase or GPT), gamma-glutamyl transferase
(GGT), and alkaline phosphatase. Three laboratory parameters
are used routinely to assess liver function: serum bilirubin, serum albumin,
and plasma prothrombin time. The yellow coloring characteristic
of jaundice is caused by a buildup of bilirubin in the blood. Bilirubin
is a yellow pigment formed by the breakdown of red blood cells
that is normally secreted by the liver in bile. Plasma prothrombin time
(international normalized ratio [INR], a blood clotting index) is a useful
indicator of liver function, since it is dependent upon blood clotting
 factor VII, which is produced by the liver (Habib, Bond, and
Heuman, 2001).



 
The presence and severity of cirrhosis has been graded using an index
called the Child-Turcotte-Pugh (CTP) score. The CTP score is
the sum of five parameter scores (prothrombin time, bilirubin, albumin,
ascites, and encephalopathy). Lower CTP scores of relatively
healthy subjects are classified as Child’s Class A, moderate scores are
classified as Child’s Class B, and the high scores of subjects requiring
liver transplants are classified as Child’s Class C (Habib, Bond, and
Heuman, 2001). Milk thistle has generally been used to treat those
with cirrhosis categorized as Child’s Class A.