For centuries, numerous hepatoprotectives originating from plant sources have been used in liver disease therapy. One such traditional herb is Silybum marianum, commonly known as milk thistle, and the extract of the seeds of S. marianum named silymarin is a component of several commercially produced hepatoprotective remedies. Milk thistle has been used medicinally for more than 2,000 years. In important medieval medical books such as Matthiolus' Book of Herbs of 1626, it is recommended “for side stitches which accompany jaundice”. In his Book of Herbs of 1679, Lonicerus writes that “it is good for an inflamed liver”. The well-known 17th-century pharmacist Nicholas Culpeper recommended the plant for the treatment of jaundice and also cited its use for opening “obstructions” of the liver and spleen. The first-century Roman author and scientist Pliny wrote of milk thistle as a wholesome food. In rural areas of Mediterranean countries, thistles are still commonly eaten as vegetables.
The most eminent and familiar member of the vast thistle family, the artichoke, also has medicinal benefits for the liver and gall bladder. Milk thistle lacks the large globular flower bud of its cousin but is just as edible and perhaps even more wholesome. What we particularly appreciate about this herb are not its petals but its seeds.
The genus name Silybum comes from the Greek “silibon” (etymologically Syllibon) = tassel. The species name marianum comes from the Latin and refers to a legend that the white spots on the leaves of this species of thistle came from the milk of the Virgin Mary nursing her child whilst fleeing to Egypt.
Milk thistle was formerly classified in the family of the Dipsacacaea, genus Carduus. The more recent botanical system puts it in the Compositae family. The pharmaceutical nomenclature is often still based on the old name Carduus, which can lead to confusion.
Milk thistle is native to the Mediterranean but is now widespread throughout the world. Usually growing in dry, sunny areas, its stem branches at the top, and reaches a height of 4 to 10 feet. The leaves are wide, waxy-lobed, toothed and thorny, with white blotches or veins. It bears red-purple spiky flowered heads (which, true to its name, resembles a thistle). The small, hard-skinned fruit is brown, spotted, and shiny.
The ripe fruit freed by the pappus is used. The commercially available remedy is derived exclusively from crops, partly in northern Germany, but it is mostly imported, mainly from Argentina and China, Romania and Hungary.
The European Commission E approved the internal use of milk thistle fruit for dyspeptic complaints. Formulations are approved for toxic liver damage and for supportive treatment in chronic inflammatory diseases and hepatic cirrhosis. Current research indicates that milk thistle fruit scavenges free radicals, increases intracellular concentration of glutathione, stabilizes the hepatocyte membrane against injury and regulates its permeability, assists in cellular generation, and increases the proliferation of Kupffer cells.1, 2, 3, 4, 5, 6
One of the major active constituents of milk thistle is silymarin, which is composed of the flavonolignans silybin, isosilybin, silychristin and silydianin. Most studies have focused on silybin and silymarin itself. Protective in vitro and in vivo effects against large numbers of toxins with different mechanisms of action have been reported for silybin and silymarin.7 The effect of flavonolignans on living systems is restricted not to one single mechanism but reflects a complex of complementary mechanisms. The essential activity of silymarin is an antioxidant effect, which is attributable to the radical scavenging ability of its flavonolignans and of other polyphenolic constituents.8 Silybin is often considered to be the substance responsible for silymarin biological activity and possesses antiinflammatory9, antifibrotic10 and antitumor11 activities in addition to liver detoxification and antioxidant activity.12, 13, 14
Antifibrotic:
Fibrosis is a process that occurs in the liver cells due to inflammation. The most common contributors to this process are environmental toxins, excess alcohol, and chronic viruses. Milk thistle not only helps maintain liver health, but slows the progression of liver fibrosis and irreversible liver damage that leads to cirrhosis.
Antioxidant:
Milk thistle has been shown to increase the production of glutathione, an important antioxidant produced by the body, as well as increase the levels of other antioxidants, such as superoxide dismutase.
Cell Protection:
Milk thistle directly aids liver cells by binding to the outside of cells and blocking the entrance of certain toxins. In addition, toxins that are already in liver cells are neutralized by silymarin. These actions also help protect against dangerous chemicals, particularly commonly prescribed medications.
Like all medicinal plants, the physiological and psychoemotional health benefits are not simply ascribed to one single component but rather the whole “essence” or “vibratory frequency” of the plant. For milk thistle, other flavonolignans and components also play roles in its unique medicinal effect.
In traditional phytotherapy, all plants have both a physiological effect and psychoemotional effect. Historically, in European phytotherapy, milk thistle’s nature is protective. From a psychoemotional perspective, this means when the psyche is confronted with emotional and physical exploitation, milk thistle promotes the ability to react to attacks and manipulations appropriately. It supports the keeping of one’s own personality and selfhood, by strengthening the active boundary of demarcation in relation to damaging psychological influences.
Psychological defense weaknesses can express themselves in opposite ways. For example, either in the inability for clearly defined boundaries and inability of saying “no”, or perhaps in an exaggerated, aggressive demarcation – such as overstepping interpersonal boundaries, interfering, meddling and attempting to control others’ interpersonal processes. Such defense weaknesses are often emotionally expressed as suppressed anger, hurt and resentment. In traditional Chinese medicine, and Ayurvedic medicine, these emotions can lead to functional disturbances of the liver, especially its process of detoxification, and thus be a root cause of many chronic diseases.
Milk thistle is sold as an oral capsule, tablet, powder and liquid extract. Dosages vary individually and for different conditions. Taken in appropriate doses, oral use of milk thistle appears to be very safe. Milk thistle can cause an allergic reaction in people who are allergic to other plants in the Asteraceae family, such as ragweed, daisies, marigolds and chrysanthemums.
References
1.Morazzoni, P., Bombardelli, E., 1995. Silybum marianum (Carduus marianus). Fitoterapia 66, 3/42.
2. Flora, K., Hahn, M., Rosen, H., Benner, K., 1998. Milk thistle (Silybum marianum) for the therapy of liver disease. Am. J. Gastroenterol. 93 (2), 139/143.
3. Kosina, P., Kren, V., Gebhardt, R., Grambal, F., Ulrichová, J., Walterová, D., 2002. Antioxidant properties of silybin glycosides. Phytother. Res. 16 (Suppl. 1), 33/39.
4. Miadonna, A., Tedeschi, A., Leggieri, E., Lorini, M., Froldi, M., Zanussi, C., 1987. Effects of silybin on histamine release from human basophil leucocytes. Br. J. Clin. Pharmacol. 24 (6), 747/752.
5. Zhao J, Sharma Y, Agarwal R. Significant inhibition by the flavonoid antioxidant silymarin against 12-O-tetradecanoylphorbol 13-acetatecaused modulation of antioxidant and inflammatory enzymes, and cyclooxygenase 2 and interleukin-1 expression in SENCAR mouse epidermis: implications in the prevention of stage I tumor promotion. Mol Carcinog 1999;26:321-333.
6. Bokemeyer C, Fels LM, Dunn T, Voigt W, Gaedeke J, Schmoll H-J, Stolte H, et al. Silibinin protects against cisplatin-induced nephrotoxicity without compromise cisplatin or ifosfamide anti-tumour activity. Br J Cancer 1996;74:2036-2041.
7. Morazzoni, P., Bombardelli, E., 1995. Silybum marianum (Carduus marianus). Fitoterapia 66, 3/42.
8. De Groot, H., Rauen, U., 1998. Tissue injury by reactive oxygen species and the protective effects of flavonoids. Fundam. Clin. Pharmacol. 12 (3), 249/255.
9. Miadonna, A., Tedeschi, A., Leggieri, E., Lorini, M., Froldi, M., Zanussi, C., 1987. Effects of silybin on histamine release from human basophil leucocytes. Br. J. Clin. Pharmacol. 24 (6), 747/752.
10. Boigk, G., Stroedter, L., Herbst, H., Waldschmidt, J., Riecken, E.O., Schuppan, D., 1997. Silymarin retards collagen accumulation in early and advanced biliary fibrosis secondary to complete bile duct obliteration in rats. Hepatology 26 (3), 643/649.
11. Katiyar, S.K., Korman, N.J., Mukhtar, H., Agarwal, R., 1997. Protective effects of silymarin against photocarcinogenesis in a mouse skin model. J. Natl. Cancer. Inst. 89 (8), 556/ 566.
12. Abenavoli L, Capasso R, Milic N, et al. Milk thistle in liver diseases: past, present, future. Phytotherapy Research. 2010;24(10):1423-1432.
13. Fried MW, Navarro VJ, Afdhal N, et al. Effect of silymarin (milk thistle) on liver disease in patients with chronic hepatitis C unsuccessfully treated with interferon therapy: a randomized, controlled trial. JAMA. 2012;308(3):274-282.
14. Loguercio C, Festi D. Silybin and the liver: from basic research to clinical practice. World Journal of Gastroenterology. 2011;17(18):2288-2301.