Milk Thistle: Cleansing the Liver
by Steve Foster

My introduction to milk thistle came in the late 1970s, while visiting herbalists along the central California coast. In the mountains there, the plant is a familiar spring wildflower (or weed, depending upon how you look at it).

Then the plant was best known as a wild edible, not an herb product. Its young leaves emerge early in the season, and with their spiny margins removed make a tasty salad green. In the mid to late 1980's herbalists and consumers in this country began to discover what Europeans had known for two thousand years—that milk thistle has a beneficial effect on the liver.

Milk thistle, known to botanists as Silybum marianum, is a member of the aster or sunflower family (Asteraceae or Compositae). It has been used as both food and medicine in Europe since ancient times. Dioscorides, a first century Greek physician gave the name Silybum to a number of edible thistles. Now the genus name Silybum is given to two species originating from the Mediterranean region, the milk thistle (Silybum marianum) and the elephant or ivory thistle (Silybum eburneum).

Native to dry soils of the Mediterranean region of southwest Europe, milk thistle has been cultivated in many parts of Europe for centuries. By the time the first edition of John Gerarde's famous Herball was published in 1597, the plant had already escaped from gardens, establishing itself throughout the English countryside. In A Modem Herbal, Maude Grieve (1931) quotes Gerarde as saying, "My opinion is that this is the best remedy that grows against all melancholy (liver-related) diseases."

It was brought to America by early settlers, probably as a food plant, and became established in the eastern United States, as well as the west. By the turn of the century, it was already common in California, in abandoned fields, old pastures, and by roadsides. It is also naturalized in South America, and Australia, where it has become thicket forming nuisance weed.

An Edible Weed

Milk thistle is a stout, branching annual or biennial growing from three to seven feet in height. The leaves become tough as they age. They are mottled with white streaks, which is where the name "milk thistle" comes from.

Milk thistle has black shiny seeds, crowned with feathery tufts like those of dandelion seeds. The subject of interest among herbalists are these seeds, which have been roasted for use as a coffee substitute, but it is their historical and modern use in the supportive treatment of liver disease that has attracted attention.

Use of the plant as: a liver protecting agent dates at least to the first century. The first century Roman naturalist Pliny the Elder (A.D. 23-79), who died in the eruption of Vesuvius, tells us that the juice of the plant, mixed with honey, is excellent for "carrying off bile." This is probably one of the first references to the use of milk thistle for liver-related disease.

Official Recognition

A thousand years later, the plant was already well known in Germany. It is mentioned in an important medieval German manuscript, the Physica of Hildegard of Bingen, the first herbal written by a woman, composed about 1150 then published in 1533. Hildegard of Bingen wrote about the uses of the roots, whole plant and leaves of Milk Thistle, which she called Venus Thistle.

In one form or another, various milk thistle seed preparations have been associated with the treatment of liver disease for over two thousand years. Historical references on its use are particularly abundant in the herbal literature of the Middle Ages, especially German herbals. However, by the turn of the century, it had become an obscure medicinal plant at best.

In 1929, a German researcher, H. Schulz, began to reinvestigate the potential value of old herbal remedies. He found a number of references to the use of milk thistle for liver ailments, which sparked further interest in the plant.

In his 1938 Textbook of Biological Remedies, Dr. Gerhard Madaus (co-founder of Madaus, AG, Cologne), noted that milk thistle seeds were the famous liver preparation of the 18th-century German physician, Rademacher, who used it for chronic liver diseases and for other conditions. By the 1930s, interest in milk thistle preparations for liver disease had again begun to grow.

The Compound is Isolated

Intensive research into the liver protecting (hepatoprotectant) properties of the plant, the responsible chemical components, and mechanisms of action, began about 30 years ago. Attempts to isolate the active components of the seed were begun in 1958. Ten years later a research team headed by H. Wagner at the University of Munich was successful in isolating silymarin, then believed to be a single compound.

Improved chemical separation methods later revealed that silymarin was not a single component but rather, a complex of chemicals known as flavonolignans. The primary components isolated and structurally characterized from silymarin include silybinin, silydianin, and silychristin. Collectively, these isoflavonolignans are found in concentrates of four to six percent in the ripe seeds. European Milk Thistle products, some of which are available on the American market, are standardized to eighty percent silymarin.

Numerous studies conducted since the late 1960s have provided an experimental basis for the pharmacological effectiveness and safety of silymarin in a number of laboratory models. Such studies have provided a scientific basis for the use of Milk Thistle in the treatment of liver disease.

According to Rudolf Fritz Weiss in Herbal Medicine (1988), compared with silymarin, few plant principles have been exclusively research in recent years. Extensive studies using animals as models have demonstrated the liver protectant effects of various proprietary German seed extracts.

According to Weiss, the efficacy of silymarin has been confirmed by extensive laboratory, historical, and clinical data.

The German version of the FDS (BGA) has published a positive monograph on Milk Thistle seed psychomedicines which allows the clinical use of the preparation for the supportive treatment of chronic inflammatory liver disorders such as chronic hepatitis, and fatty infiltration of the liver by alcohol and other chemicals and cirrhosis of the liver; (Monograph Cardui Marie Fructus 1986). Further studies have noted that pretreatment with silymarin inhibits alcohol-induced liver damage.

Effective and Safe

It should be noted that even when given in large doses, silymarin has proven to be without toxic effects, and has no harmful actions on embryos. Widespread human use and numerous animal studies have proven the safety of milk thistle seeds and silymarin–containing preparations. According to the official German monograph the only side effect report is a mild laxative in isolated cases.

Milk thistle seed preparations have been used for the treatment of the liver disease since antiquity. At one time or another, virtually all parts of the plant have been used as both food and medicine with no reports of toxicity. The extensive chemical, pharmacological and clinical research conducted over the past 30 years has revealed its active components, mechanism of action, and its efficacy in human liver disease.

Now milk thistle is widely used, especially in Europe, for the support treatment of fatty infiltration and degeneration of the liver of alcohol and other toxic chemicals as well as the treatment of chronic hepatitis and cirrhosis. It has both a protective and restorative effect on the liver.

Milk thistle is one of those fascinating plants, whose use, supported by 2,000 years of historical use, has emerged as an important example of how traditional information can be used for the development of modern herb products.

Permission to reprint granted from Health Foods.

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