Milk thistle

This article is about the true milk thistles. For another plant that is sometimes referred to as a milk thistle, see Sow thistle (disambiguation).

Milk thistle
Silybum marianum
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Asterids
Order:	Asterales
Family:	Asteraceae
Subfamily:	Carduoideae
Tribe:	Cynareae
Genus:	Silybum Adans.
Species
Silybum eburneum Silybum marianum Silybum × gonzaloi

The milk thistle is a thistle of the genus Silybum Adans., a flowering plant of the daisy family (Asteraceae). They are native to the Mediterranean regions of Europe, North Africa and the Middle East. The name "milk thistle" derives from two features of the leaves; they are mottled with splashes of white and they contain a milky sap.^[1]

The seeds of the milk thistle have been used for 2,000 years to treat chronic liver disease and protect the liver against toxins.^[1][2] Increasing research is being undertaken on the physiological effects, therapeutic properties and possible medical uses of milk thistle.^[3]

Description and classification

Members of this genus grow as annual or biennial plants. The erect stem is tall, branched and furrowed but not spiny. The large, alternate leaves are waxy-lobed, toothed and thorny, as in other genera of thistle. The lower leaves are cauline (attached to the stem without petiole). The upper leaves have a clasping base. They have large, disc-shaped pink-to-purple, rarely white, solitary flower heads at the end of the stem. The flowers consist of tubular florets. The phyllaries under the flowers occur in many rows, with the outer row with spine-tipped lobes and apical spines. The fruit is a black achene with a white pappus.

Only two species are currently classified in this genus:

• Silybum eburneum Coss. & Dur., known as the Silver Milk Thistle, Elephant Thistle, or Ivory Thistle
  • Silybum eburneum Coss. & Dur. var. hispanicum
• Silybum marianum (L.) Gaertner, the Blessed Milk Thistle, which has a large number of other common names, such as Variegated Thistle.

The two species hybridise naturally, the hybrid being known as Silybum × gonzaloi Cantó , Sánchez Mata & Rivas Mart. (S. eburneum var. hispanicum x S. marianum)

A number of other plants have been classified in this genus in the past but have since been relocated elsewhere in the light of additional research.

S. marianum is by far the more widely known species. Milk thistle is believed to give some remedy for liver diseases (e.g. viral hepatitis) and the extract, silymarin, is used in medicine. Mild gastrointestinal distress is the most common adverse event reported for milk thistle. The incidence is the same as for placebo.^[4] A laxative effect for milk thistle has also been reported infrequently.^[5]

Nomenclature

Traditional milk thistle extract is made from the seeds, which contain approximately 4-6% silymarin.^[5] The extract consists of about 65-80% silymarin (a flavonolignan complex) and 20-35% fatty acids, including linoleic acid.^[6] Silymarin is a complex mixture of polyphenolic molecules, including seven closely related flavonolignans (silybin A, silybin B, isosilybin A, isosilybin B, silychristin, isosilychristin, silydianin) and one flavonoid (taxifolin).^[6] Silibinin, a semipurified fraction of silymarin, is primarily a mixture of 2 diasteroisomers, silybin A and silybin B, in a roughly 1: 1 ratio.^[1][6] In clinical trials silymarin has typically been administered in amounts ranging from 420–480 mg per day in two to three divided doses.^[7] However higher doses have been studied, such as 600 mg daily in the treatment of type II diabetes and 600 or 1200 mg daily in patients chronically infected with hepatitis C virus.^[8][9] An optimal dosage for milk thistle preparations has not been established. It is known to help hangovers.

Health benefits

Thistle flower

Dried thistle flowers at the end of summer

For many centuries extracts of milk thistle have been recognized as "liver tonics."^[6] Research into the biological activity of silymarin and its possible medical uses has been conducted in many countries since the 1970s, but the quality of the research has been uneven.^[3] Milk thistle has been reported to have protective effects on the liver and to greatly improve its function. It is typically used to treat liver cirrhosis, chronic hepatitis (liver inflammation), toxin-induced liver damage including the prevention of severe liver damage from Amanita phalloides ('death cap' mushroom poisoning), and gallbladder disorders.^[5][2]

Reviews of the literature covering clinical studies of silymarin vary in their conclusions. A review using only studies with both double-blind and placebo protocols concluded that milk thistle and its derivatives "does not seem to significantly influence the course of patients with alcoholic and/or hepatitis B or C liver diseases."^[10] A different review of the literature, performed for the U. S. Department of Health and Human Services, found that, while there is strong evidence of legitimate medical benefits, the studies done to date are of such uneven design and quality that no firm conclusions about degrees of effectiveness for specific conditions or appropriate dosage can yet be made.^[11]

Toxin-induced liver damage

Research suggests that milk thistle extracts both prevent and repair damage to the liver from toxic chemicals and medications. Workers who had been exposed to vapors from toxic chemicals (toluene and/or xylene) for 5–20 years were given either a standardized milk thistle extract (80% silymarin) or placebo for 30 days.^[12] The workers taking the milk thistle extract showed significant improvement in liver function tests (ALT and AST) and platelet counts vs. the placebo group.

The efficacy of silymarin in preventing drug-induced liver damage in patients taking psychotropic drugs long-term has been investigated.^[13] This class of drugs is known to cause liver damage from oxidation of lipids. Patients taking silymarin in the study had less hepatic damage from the oxidation of lipids than patients taking the placebo.

A clinical trial in humans showed that silymarin (140 mg orally 3 times daily) was not effective when used for 1 year in combination with ursodeoxycholic acid (UDCA) for the treatment of primary biliary cirrhosis.^[14] A study in baboons indicated that continuous intragastric infusion of silymarin retarded the development of alcohol-induced hepatic fibrosis over a 3-year period. The authors suggested that the failure of silymarin to show beneficial effects in other clinical trials may have been due to poor compliance with treatment, resulting in insufficient dosing.^[15]

In a 2009 study published in the journal Cancer, milk thistle showed promise in reducing the liver damaging effects of chemotherapy in a study of 50 children.^[16][17]

Amanita mushroom poisoning

The efficacy of thirty different treatments was analyzed in a retrospective study of 205 cases of Amanita phalloides (death cap) mushroom poisoning.^[18] Both penicillin and hyperbaric oxygen independently contributed to a higher rate of survival. When silybin [silibinin] was added to the penicillin treatment, survival was increased even more. In another 18 cases of death cap poisoning, a correlation was found between the time elapsed before initiation of silybin therapy, and the severity of the poisoning.^[19] The data indicates that severe liver damage in Amanita phalloides poisoning can be prevented effectively when administration of silybin begins within 48 hours of mushroom intake. In a recent 2007 event, a family of six was treated with milk thistle and a combination of other treatments to save them from ingested poisonous mushrooms. While five of the six made a full recovery, the grandmother showed liver recovery but was overcome by kidney failure related to the poisonous mushrooms.^[20]

Other uses

Beside benefits for liver disease, other unproven treatment claims include:

• Lowering cholesterol levels ^[21]
• Reducing insulin resistance in people with type 2 diabetes who also have cirrhosis,^[21][22][23]
• Reducing the growth of cancer cells in breast, cervical, and prostate cancers.^[24]
• Used in many products claiming to reduce the effects of a hangover^[25]
• Reducing liver damaging effects of chemotherapeutic drugs^[16]
• Clinical study has shown that liver function tests can be improved in active hepatitis patients.^[26]
• silymarin may have use, potentially, in the treatment of diabetic nephropathy.^[27]

Use as food

Around the 16th century the milk thistle became quite popular and almost all parts of it were eaten. The roots can be eaten raw or boiled and buttered or par-boiled and roasted. The young shoots in spring can be cut down to the root and boiled and buttered. The spiny bracts on the flower head were eaten in the past like globe artichoke, and the stems (after peeling) can be soaked overnight to remove bitterness and then stewed. The leaves can be trimmed of prickles and boiled and make a good spinach substitute or they can also be added raw to salads.^[28]

See also

• Cnicus (Blessed thistle)
• Silybum marianum

References

1. ^ ^{a b c} Hogan F, Krishnegowda N, Mikhailova M, Kahlenberg M. (2007). Flavonoid, silibinin inhibits proliferation and promotes cell-cycle arrest of human colon cancer. J Surg Res 143: 58-65.
2. ^ ^{a b} Tamayo C, Diamond S. (2007). Review of clinical trials evaluating safety and efficacy of milk thistle (Silybum marianum [L.] Gaertn.). Integrative Cancer Therapies. 6: 146-157.
3. ^ ^{a b} Gazák R, Walterová D, Kren V (2007). "Silybin and silymarin--new and emerging applications in medicine". Curr. Med. Chem. 14 (3): 315–38. doi:10.2174/092986707779941159. PMID 17305535. 
4. ^ Rainone F. (2005). Milk thistle. American Family Physician72: 1285-1288.
5. ^ ^{a b c} Greenlee H, Abascal K, Yarnel E, Ladas E. (2007). Clinical applications of Silybum marianum in oncology. Integrative Cancer Therapies 6: 158-165.
6. ^ ^{a b c d} Kroll DJ, Shaw HS, Oberlies NH.(2007). Milk thistle nomenclature: why it matters in cancer research and pharmacokinetic studies. Integrative Cancer Therapies. 6: 110-119.
7. ^ Rainone F. (2007). Milk thistle. American Family Physician. 72: 1285-1288.
8. ^ Huseini HF, Larijani B, Heshmat R et al. (2006). The efficacy of Silybum marianum (L.)Gaertn. (silymarin) in the treatment of type II diabetes: a randomized, double-blind, placebo-controlled, clinical trial. Phytother Res. 20: 1036-1039.
9. ^ Gordon A, Hobbs DA, Bowden DS et al. (2006). Effects of Silybum marianum on serum hepatitis C virus RNA alanine aminotransferase levels and well-being in patients with chronic hepatitis C. J Gastroenterol Hepatol 21: 275-280.
10. ^ Rambaldi A, Jacobs BP, Iaquinto G, Gluud C (2005). "Milk thistle for alcoholic and/or hepatitis B or C liver diseases--a systematic cochrane hepato-biliary group review with meta-analyses of randomized clinical trials". Am. J. Gastroenterol. 100 (11): 2583–91. doi:10.1111/j.1572-0241.2005.00262.x. PMID 16279916. 
11. ^ Lawrence, Valerie MD, MSc et al. (2000). "Milk Thistle: Effects on Liver Disease and Cirrhosis and Clinical Adverse Effects". AHRQ Publication No. 01-E025. 
12. ^ Szilard S, Szentgyorgyi G, Dhanalakshmi S et al. (1988). Protective effect of Legalon in workers exposed to organic solvents. Acta Med Hung. 45: 249-256.
13. ^ Palasciano G, Portincasa P, Palmieri V et al. (1994). The effect of silymarin on plasma levels of malon-dialdehyde in patients receiving long-term treatment with psychotropic drugs. Curr Ther Res Clin Exp. 55: 537-545.
14. ^ Angulo P, Patel T, Jorgensen RA, Therneau TM, Lindor KD (2001). "Silymarin in the treatment of patients with primary biliary cirrhosis with a suboptimal response to ursodeoxycholic acid". Hepatology. 2001 Feb;33(2): 483-4. 32 (5): 897–900. doi:10.1053/jhep.2000.18663. PMID 11050036. 
15. ^ Lieber CS, Leo MA, Cao Q, Ren C, DeCarli LM. (2003). "Silymarin retards the progression of alcohol-induced hepatic fibrosis in baboons". Journal of Clinical Gastroenterology 37 (4): 336–9. doi:10.1097/00004836-200310000-00013. PMID 14506392. 
16. ^ ^{a b} Reuters.com
17. ^ http://www.sciencedaily.com/releases/2009/12/091215172325.htm
18. ^ Floersheim GL, Weber O, Tschumi P et al. [Clinical death-cap (Amanita phalloides) poisoning: prognostic factors and therapeutic measures. Analysis of 205 cases]. Schweiz Med Wochenschr. 112: 1164-1177.
19. ^ Hruby K, Fuhrmann M, Csomos G et al. [Pharmcotherapy of Amanita phalloides poisoning using silybin].Wein Klin Wochenschr. 95: 225-231.
20. ^ American Botanical Council (2007). "Intravenous Milk Thistle Compound Used to Save Victims of Poisonous Mushrooms". HerbalGram (74): 16. 
21. ^ ^{a b} Webmd.com
22. ^ Chiro.org
23. ^ Antimetastatic efficacy of silibinin: Molecular mechanisms and therapeutic potential against cancer Deep G., Agarwal R. Cancer and Metastasis Reviews 2010 29:3 (447-463)
24. ^ National Center for Complementary and Alternative Medicine. "Milk Thistle". National Institutes of Health. http://nccam.nih.gov/health/milkthistle/.  - General information on milk thistle
25. ^ Femalefirst.co.uk
26. ^ Buzzelli, G; Moscarella, S; Giusti, A; Duchini, A; Marena, C; Lampertico, M (1993). "A pilot study on the liver protective effect of silybin-phosphatidylcholine complex (IdB1016) in chronic active hepatitis". International journal of clinical pharmacology, therapy, and toxicology 31 (9): 456–60. PMID 8225695. 
27. ^ Soto C, Pérez J, García V, Uría E, Vadillo M, Raya L"Effect of silymarin on kidneys of rats suffering from alloxan-induced diabetes mellitus." Phytomedicine. 2010 Dec 1;17(14):1090-4
28. ^ Edible-plants.com

External links

• Clinical study with 50 children shows milk thistle may limit liver damage from chemotherapy drugs
• Intravenous Milk Thistle Compound Used to Save Victims of Poisonous Mushrooms
• Milk thistle (Silybum marianum (L.) Gaertn.) - information at the site of Washington State Noxious Weed Control Board
• Flora K, Hahn M, Rosen H, Benner K (1998). "Milk thistle (Silybum marianum) for the therapy of liver disease". Am. J. Gastroenterol. 93 (2): 139–43. doi:10.1111/j.1572-0241.1998.00139.x. PMID 9468229. 
• Hepatitis C Treatment Conclusions by various referenced studies on the potential use of milk thistle in treating Hepatitis C and other liver health issues.