"Milk Thistle" has emerged as the most widely known English common name for the plant. Older works list it as Mary Thistle, St. Mary Thistle, Marian Thistle, Lady’s Thistle and Holy Thistle (not to be confused with Blessed Thistle Cnicus benedictus). Latin synonyms include Cardurus marianus L., and Cnicus marianus. Silybum derives from a name applied to some edible thistles by the first century Greek physician Dioscorides. The genus contains two species. The other species is S.eburneum Indigenous to the Mediterranean region. The specific name marianum preserves the legend that the white mottling of the leaves was caused by a drop of the Virgin Mary’s milk (Nicholson 1886-87). The plant is also traditionally used as a galactogogue (stimulating milk production), perhaps contributing to word origins of the common name.

In European gardens the plant has been cultivated as a vegetable. It was still grown in old-fashioned British gardens at the end of the nineteenth century (Henderson 1889). The young leaves (with spines removed) were used in spring salads and as a spinach substitute. Young stalks, peeled and soaked, are eaten like a sparagus. The roots, soaked in water overnight to remove bitterness, are eaten like salsify. Milk Thistle’s flower receplacle, resembling an artichole, was cooked and eaten like artichokes (Hedrick 1919, Grieve 1931). Roasted seeds have been employed is a coffee substitute (Uphof 1968). Adverse effects from ingesting any plant part are generally lacking from the literature. Animal experiments have shown that seed extracts are safe, even in large doses, with practically no side effects, as well as no embryo toxic effect (Weiss 1988). Adverse effects in human studies with the seed extract (silymarin) are also generally absent (Der Marderosian and Liberti 1988). A mild laxative effect has been observed in isolated cases (Monograph Cardui Mariae Frustus 1986).

In one form or another, various preparations of Milk Thistle specially the seeds, have been used medicinally for over 2,000 years. In modern research scientists often attempt to find new biologically active plant substances through random screening methods. However, Silybum is a classic example of the value of utilizing historical records for the development of modern herb products. Its usr as a liver-protecting agent dates to early Greek references. The first century Roman writer Pliny the Elder (A.D. 23-79), noted that the juice of the plant mixed with honey is excellent for "carrying off bile" (Jones 1966). Historical references on the plant are particularly abundantin the herbal literature of the Middle Ages, including the anti-liver toxic activity of the seeds (Halbach 1976).

While native to Southern Europe, the plant was found in England by the end of the sixteenth century. Grieve (1931) quotes Gerard (1597). "My opinion is that this is the best remedy that grows against all melancholy diseases" [diseases of the liver ].

Culpepper (1787 ed.) notes that it is effectual "to open the obstructions of the liver and spleen, and thereby is good against the jaundice." He also writes, "The seed and distilled water are held powerful to all the purpose aforesaid, and besides, it is often applied both inwardly to drink, and outwardly with cloths or spunges [sins], to the region of the liver, to cool the distemper there of..."

The plant is absent from most Amerian works on medicinal plants until the end of the nineteenth century. Felter and Lloyd (1898) list the seeds as Cardus marianus. They write, " It is an old remedy which had nearly passed out of use and has more recently been revived." They also state that "Congestion of the liver, spleen, and kidneys is relieved by its use."

A tincture of the whole plant is an official preparation of the first United States Homeopathic Pharmacopeia (Aron. 1878). In homeopathy the seed tincture is used for liver disorders, jaundice, gall stones, peutonitis, coughs, bronchilis, varicose veins, and congestion of the uterus (Schauerberg and Paris 1977). A 1985 German menograph on the use of Silybum marianum in homeopathy includes indications for diseases of the gall bladder and liver.

Intensive research in the hepatoproleclant (liver protecting) effects of Milk Thistle began twenty years ago. In Germany, Milk Thistle seed extracts have been marketed for many years. Attempts to isolate the primary active chemical components were under way by 1958, but there had been few attempts to characterize the chemical components prior to 1965 (Vogel 1976). Wagner et al. (1968) first isolated silymarin from the seeds, providing an opportunity for establishing a scientific basis for use in treating liver diseases. Silymarin is found in concentrations of 4 to 6 percent in the ripe seeds (Der Marderosian and Liberti 1988). Later it was found that silymarin was not a single component, but a mixture of complex compounds known as flavonolignans. The first chemical compounds isolated and struclurally characterized were silybin, silydianin and silychristin (Wagner and Seligmann 1985). A number of other flavonolignans have also been found in the seeds, in addition to apigenin, silybonol, and myristic, palmitic, stearic, and oleic acids (Der Marderosian and Liberti 1988).