Milk thistle: powerful antioxidant for liver protection & body detoxification

Milk thistle is "one of the most ancient known herbal medicines," Daniel B. Mowrey, Ph.D., remarks in his 1993 work, Herbal Tonic Therapies.

Called Silybum marianum in Latin, this plant is an annual, or biennial, thistle which flowers from June through September, according to A Field Guide to Medicinal Plants: Eastern and Central North America (1990) by Steven Foster and James A. Duke, Ph.D.

Native to Europe, it today grows in Europe, Africa, Asia, parts of the United States (such as California) and in Mediterranean countries.

"It is an ancient plant about which many authors have written," Frank Murray pointed out in "Milk Thistle: Ancient Herb, Modern Uses" (Better Nutrition 50:18-19, 1988).

With the spines removed, the young leaves are sometimes eaten as a vegetable. Traditionally, Foster and Duke inform us, a tea is made from the whole plant, which concoction is said to "improve appetite and allay indigestion," as mentioned above.

The leaves of milk thistle have been described as "without downe, alltogether slippery, of a light greene and speckled with white and milkie spots and lines drawne divers wales," according to Geoffrey Grigson's The Englishman's Flora (1955).

Five of milk thistle's known compounds

David Hoffmann's The New Holistic Herbal (1992) notes that milk thistle includes the following compounds: silybin, silydianin, as well as silychristin, essential oil, and mucilage.

"At some point in time, milk thistle seed has been used in the treatment of gallstones; disorders of the liver, gallbaldder and spleen; as a cholagogue to promote the flow of bile [...] as a remedy for jaundice from any cause; for indigestion, dyspepsia, lack of appetite and/or digestive disorders; and to treat: peritonitis, coughs, bronchitis, uterine congestion and varicose veins," says Herbal Tonic Therapies.

The liver is a main treatment area

The liver: the body's great detoxifier. The liver is indeed our body's great detoxifier. After skin, the second largest organ in the body, the liver, is responsible for many aspects of metabolism. Since all foods, liquids and drugs pass through the liver on their way from the intestine to the bloodstream, the liver is, therefore, vulnerable to many types of toxins.

Environmental toxins include: trichloroethylene (dry cleaning fluid); benzene; methylene chloride (used to decaffeinate coffee); pesticides, such as DDT; heavy metals including arsenic and lead; workplace toxins like styrene and vinyl chloride; and a range of products found in common air pollution.

Protects the liver. In fact, as early as the 12th century, the milk thistle plant was being used as a treatment for liver disease. In 1986, Varro Tyler, Ph.D., noted that silymarin was even then successfully being marketed as a hepatoprotective drug to shield the liver from infections, such as viral hepatitis. Very often used for treatment of cirrhosis, hepatitis, liver poisoning and from chemicals or substance abuse, it is said that "silymarin, a seed extract, dramatically improves liver regeneration" in disease and poisoning, Foster and Duke point out.

Milk thistle protects the liver from certain toxic effects

In fact, a large number of published reports "show that milk thistle seed extract protects the liver against the effects of toxins such as carbon tetrachloride, hexobarbital [...] thiocetamide and salts of rare earth metals," Mowrey adds.

Laboratory experiments have demonstrated the protective effects of silymarin against both natural toxins, like those from carbon tetrachloride, a standard hepatotoxic chemical used in laboratory evaluation of liver drugs, and from the deadly Amanita (Death Cap) mushroom.

"Cures" Amanita mushroom poisoning. According to a non-controlled (for ethical reasons) clinical study by G. Vogel, in 1981, 49 patients with Death Cap mushroom poisoning were under observation in Germany, Austria, Italy, Switzerland and France. "Silybin was administered," Vogel wrote. "The results ranged from amazing to spectacular."

What is this silymarin, anyway? Silymarin, it should be mentioned, is not a single compound, as such, but a mixture of naturally antioxidative chemicals, which used to be termed "flavonolignans," but are more often today called "flavonoids."

According to Frank Murray in "Milk Thistle Works to Keep Your Liver In Good Health" (Better Nutrition, January 1990), "meticulous research in Germany in the early 1970's isolated the active principles in milk thistle." They are: silybin, silydianin and silychristin, which together form the substance silymarin.

"Silybin is a flavonoid," explained Michael Colgan, Ph.D., in 1989. "Bioflavonoids act generally in the body to increase membrane strength and reduce membrane permeability. Silybin appears to act in this way specifically on liver cells. The flow of chemicals across membranes is the major way in which your biochemistry works. Any substance that alters this flow can have profound effects."

Strengthens and stabilizes cell membranes. "Milk thistle appears to protect and heal the liver in three primary ways," Mowrey explains.

"First, it acts directly on the cell membrane of the liver, and probably most other cells of the body by stabilizing and strengthening that structure. In support of this concept is the finding that milk thistle extract and some of the toxins actively compete for the same cell-membrane receptor sites. That toxins are unable to affect cell membranes in the presence of milk thistle extract argues for the stabilizing action of these substances."

"The observable result," Mowrey continues, "is the regeneration of liver cells," indicating that milk thistle's compounds are excellent free-radical-scavenging antioxidants.

Acts as an antioxidant. Milk thistle can act as an antioxidant with many times more antioxidant activity than vitamin E, suggested AIBR Scientific Reviews, in 1987.

Compounds in the plant interfere with the formation of liver-damaging leukotrienes, while inhibiting prostaglandin synthesis during inflammatory reactions.

Milk thistle is a free-radical scavenger

"By combining our current understanding of the physiochemical properties of milk thistle, we can better understand why it can be a therapeutic substance in the treatment of liver disorders; milk thistle is a free-radical scavenger," Murray explained in Better Nutrition (1990).

"It interferes in the production of leukotrienes and stimulates protein synthesis," Murray added.

It is suggested, in fact, that one of the ways milk thistle speeds up the regeneration of damaged liver tissue is by signalling for cellular protein synthesis.

Lessens alcohol-induced damage. "Silymarin appears to be capable of lessening alcohol-induced liver damage when taken prior to alcohol consumption and is used clinically in the treatment of alcohol-induced liver damage," Rob McCaleb explained in a Better Nutrition for Today's Living article from 1991.

In placebo-controlled experiments, silymarin has been shown useful in treating alcohol- and drug-induced liver disease. A study by H. Feher, et al., in 1990, showed that six months of treatment significantly improved liver function in 36 patients with alcohol-induced liver disease.

Compounds in milk thistle interfere with enterohepatic circulation. Since toxins are continuously cycled "between the gastrointestinal tract and the liver," Mowrey goes on, toxicity produced through what is called a "continuous enterohepatic circuit" usually takes quite a while to develop.

When milk thistle compounds are administered, the enterohepatic circuit is interrupted. The primary absorption of toxins is now blocked, and their reabsorption is mostly prevented, as well.

"Cells not yet poisoned are protected from damage from circulating toxins," Herbal Tonic Therapies says.

These damage-protected cells now "act as centers for the generation of new liver cells. With time, complete restoration of the liver is possible."

REFERENCES

American Institute for Biosocial Research. "Milk Thistle," AIBR Scientific Reviews Number 18, 1987.

Colgan, Michael, Ph.D. "Milk Thistle: Unique Protection for the Liver," Nutrition and Fitness 8 (3), 1989.

Feher, H., et al. "Hepatoprotective Activity of Silymarin Therapy in Patients With Chronic Alcoholic Liver Disease" Orvosi Hetilap, (Hungarian Journal) 130:51, 1990.

Foster, Steven, and Duke, James A. A Field Guide to Medicinal Plants: Eastern and Central North America. Boston: Houghton Mifflin Company, 1990, p. 198.

Hoffmann, David. The New Holistic Herbal. Rockport, Mass.: Element, Inc., 1992, p. 215.

McCaleb, Rob. "Milk Thistle for Liver Protection," Better Nutrition for Today's Living January 1991, pp. 32-34.

Murray, Frank. "Milk Thistle Works to Keep Your Liver In Good Health," Better Nutrition 52:20-21, 1990.

Tyler, Varro E., Ph.D. "Plant Drugs in the 21st Century," Economic Botany 40:279-288, 1986.

Vogel, G. "A Peculiarity Among the Flavonoids -- Silymarin, A Compound Active On the Liver." Proceedings of the International Bioflavonoid Symposium. Munich, West Germany, 1981.

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