In
an increasingly toxic world, we place growing burdens on the body's detoxification
system, the hub of which is the liver. Millions of compounds are detoxified within
each liver cell, or hepatocyte. Inevitably, this wear and tear compromises liver
cells and surrounding connective tissue. Hepatotoxicity is fast becoming a
major health issue. In fact, many practitioners believe poor liver function caused
by toxin accumulation or by liver-function decline may contribute to other seemingly
unrelated illnesses, such as rheumatoid arthritis, eczema, migraine headaches
and premenstrual syndrome, and may manifest symptoms of its own. As a result,
milk thistle (Silybum marianum) is widely prescribed by herbalists throughout
Europe and the Americas for liver protection.
Milk thistle, also known as St. Mary's thistle and lady's thistle, is native to
Asia Minor, North Africa, southern Europe and southern Russia. It has been naturalized
to central Europe, North and South America, and South Australia. The herb has
dark-green prickly leaves mottled or streaked with white veins, blooms from June
to September and can grow to six feet tall. Its medicinal properties are found
in the small, hard fruits, sometimes called seeds but known technically as achenes,
that appear after the plant flowers.
Milk thistle fruits contain a mixture of flavonolignans--a unique group of carbohydrates
that share a common chemical structure. These flavonolignans, the plant's active
constituents, are known collectively as silymarin. Silymarin usually comprises
about 1.5 to 3 percent of the fruit and contains silybinin, the major constituent,
along with isosilybin, dihydrosilybin, silydianin, silychristin, and probably
a few flavonoids. The fruits also contain 20 to 30 percent fixed oil (a combination
of fatty acids that are solid at room temperature), mucilage, protein and taxifolin
(a chemical with unknown significance).
Although milk thistle's mechanism of action has not been fully explained, the
herb has a long history of use as a liver protectant and liver decongestant. (A
liver decongestant stimulates bile flow through the liver and gallbladder, thus
reducing stagnation and preventing gallstone formation and bile-induced liver
damage.) Pharmacological investigations have centered on silymarin, which
is most notable for its antihepatotoxic activity. This effect has been demonstrated
against a variety of potent liver toxins including those from the death cap mushroom
(Amanita phalloides).1,2 S. marianum extract works as both a preventive and antidote
for death cap mushroom poisoning. Intravenous administration up to 48 hours after
ingestion is effective.3
Finnish researchers conducted a double-blind, controlled study to look at the
effect of milk thistle fruit extract on liver inflammation. They measured levels
of serum transaminase, an enzyme released from inflamed liver cells, in 97 patients.
All subjects reportedly abstained from alcohol during the four-week study during
which they received either a 420 mg daily dose of standardized S. marianum extract
(Legalon, manufactured by Madaus AG of Germany) or placebo. Subjects who received
the extract showed a statistically significant decrease in liver enzymes compared
with those taking placebo.4
In a larger clinical trial, researchers assessed the benefits of milk thistle
extract on 170 patients, 91 of them alcoholics with liver cirrhosis. Subjects
received 140 mg silymarin three times daily for 41 months. The four-year survival
rate was 58 percent in the silymarin group and 39 percent in the placebo group--a
difference of 19 percent. The reduced death rate among those taking silymarin
was most pronounced in the alcoholic cirrhosis subgroup. There were no side effects
from silymarin.5 This study is significant for several reasons. The results
support the idea that long-term treatment with milk thistle extract is beneficial
and not likely to be harmful. These results also suggest milk thistle extract
may be particularly effective for patients with alcohol-induced liver damage.
In all, studies suggest S. marianum protects the liver. It is prescribed for
any condition of threatened or obvious hepatotoxicity including chronic daily
exposure to environmental pollutants, toxic effects of viral hepatitis, toxic
side effects of certain medications, toxicity from chronic alcohol use, cirrhosis
and fatty degeneration of the liver. Milk thistle extract should help improve
liver function, protect hepatocytes and increase bile flow for anyone with these
conditions. The antihepatotoxic effects are quite pronounced while the liver-decongesting
and bile-stimulating effects are mild and gentle. This herb is extremely well
tolerated.
Milk thistle is effective in a variety of preparations, though the traditional
one is a medicinal tea or decoction. Silymarin is poorly soluble in water but
historical use indicates its bioavailability increases if the crushed fruits are
soaked overnight before being boiled for 15 minutes. A therapeutic tea contains
1 to 3 tablespoons of crushed fruits per 8 to 10 ounces of water. Another preparation
is alcohol and water extraction, commonly known as a tincture. Encapsulated standardized
milk thistle extract is the preparation studied in clinical trials. Extracts are
typically standardized to 70 percent of the silymarin complex. The typical dose
is 200 to 420 mg daily taken in three divided doses with meals for eight weeks,
then 280 mg/day in three divided doses. There are no known side effects or contraindications,
and this herb is safe for use during pregnancy and lactation.
Milk thistle can be taken as a preventive measure, particularly if a person eats
chemically processed foods, is exposed regularly to foreign compounds that require
detoxification, has a known liver disease or family history of liver disease,
or drinks alcohol regularly. Long-term continued use has no known side effects
or contraindications. Recommend that customers discontinue use for two to seven
days every eight weeks to maintain effectiveness, as they should with any herbal
medicine.
Pollutants, toxic medications and exposure to infectious organisms underscore
the need for liver protection. Milk thistle offers a reliable and safe solution.
Lise N. Alschuler, N.D., received her degree from Bastyr University, Bothell,
Wash., where she is currently the clinical medical director. She also has a private
practice in Seattle.
References
1.Faulstich H, et al. Silybin inhibition of amatoxin uptake in the perfused rat
liver. Arzneim-Forsch Drug Res 1980;30:452-4.
2.Tuchwever B, et al. Prevention of silybin of phalloidin induced acute hepatoxicity.
Toxicol Appl Pharmacol 1979;51:265-75.
3.Hruby K, et al. Effect of the flavolignans of Silybum marianum L. on lipid peroxidation
in rat liver microsomes and freshly isolated hepatocytes. Pharmacol Res 1992;25:147-54.
4.Salmi H, Sarna S. Effect of silymarin on chemical, functional, and morphological
alterations of the liver. Scand J Gastroenterol 1982;17:517-21.
5.Ferenci P, et al. Randomized, controlled trial of silymarin treatment in patients
with cirrhosis of the liver. J Hepatol 1989;9:105-13.
6.Nassauto G, et al. Effect of silibinin on biliary lipid composition: experimental
and clinical study. J Hepatol 1991;12:290-5.
