Natural Products

Milk Thistle

Silybum marianum, Chardon-Marie

Efficacy

• Indications with proven efficacy:
  None
• Indications with possible, but poorly documented efficacy - the use of this product cannot be recommended:
  Amanita (mushroom) poisoning (intravenously)
  Dyspeptic symptoms
  
• Also used for these other indications, but with no proof of efficacy:
  Alcoholic liver disease
  Chronic inflammatory liver disease
  Iatrogenic liver disease
  Lactation stimulation
  Psoriasis

Security

• Risk of Drug Interactions: Low
• Adverse Effects: Rare

What is it?

Milk thistle grows extensively in every part of the world. Because it can grow easily in many habitats, it is often found along the edge of our roads. This tall plant, 5 to 10 feet high, has thorny leaves and purple flowerheads. The seeds obtained from dried flowerheads are used for their medicinal properties. Milk thistle has been used by man for over two thousand years. It apparently has antioxidant properties as well as a protective effect on the liver. These effects are attributed to silyramine, a mix of three isomers (silibilin, silichristin and silidianin) found in the seeds. Silyramine is weakly soluble in water, which explains why water-based products, such as tea, are ineffective. Oral use requires a concentrated product. The mechanisms of action of milk thistle are still not clearly established. Milk thistle appears to improve liver regeneration, stop liver toxins from penetrating into liver cells and impair the oxydative action of free radicals.

Warning

In 2004, Canada adopted new regulations that control the manufacturing, packaging, labeling and importing of natural health products. The new regulations also include an adverse reaction reporting system. Products that conform to the regulation's criteria are identified with a natural product number (NPN) or homeopathic medicine number (DIN-HM) and can be legally sold in Canada. This number indicates that the product meets specific criteria for safety and purity, not that it is effective for any indication.

Medicinal plants content varies naturally from plant to plant – just as fruits from the same package may vary in taste and texture. There is no standard to measure the active content of each plant. Thus, efficacy of natural products should be expected to vary from brand to brand as well as from bottle to bottle of the same brand.

For more information about the Natural Health Products Regulations, or to check if a product has been assessed, visit the Health Canada website at http://www.hc-sc.gc.ca/dhp-mps/prodnatur/index-eng.php.

Does it work?

There is no evidence that milk thistle is effective in any indication. However it is used to treat certain medical conditions in which it may be of some benefit:

• Amanita poisoning:
  Used for amanita poisoning when administered intravenously within 48 hours of ingestion of Amanita phalloides. A common dose is 20 to 50 mg/kg/day of silibin.
• Dyspeptic symptoms:
  A typical dose is 12 to 15 grams of milk thistle seeds or 420 to 630 mg daily of a 70 to 80% silyramine extract is recommended.
• Chronic inflammatory, iatrogenic or alcoholic liver diseases:
  Milk thistle might be effective. Doses from 420 to 630 mg daily of a 70 to 80% silyramine extract have been used.

There is insufficient reliable information to conclude that milk thistle is effective in any other indication.

Is it safe?

• Milk thistle is not associated with any particular toxicity. No precise adverse effects have been attributed to this product. However, since syliramine can stimulate the liver and biliary functions, some individuals may experience mild, transient diarrhea.
• Even though some authors claim that milk thistle can be used safely by pregnant and breast-feeding women, no safety data are available concerning its use during pregnancy and breast-feeding. Pregnant and lactating women should be prudent and avoid milk thistle products.
• No drug interactions are known.
• Some people allergic to plants from the Asteraceae/Compositae family (ragweed, chrysanthemums, daisies, etc.) may be allergic to milk thistle.

Clinical notes

• Milk thistle extract has been found effective in the treatment of dyspeptic disturbances and amanita poisoning. Studies have shown very few adverse effects related to milk thistle use. This plant, which has been used by man for over 2000 years, appears to be very promising. A standardized silibin preparation is commercially available in Europe under the trade name Legalon

References

1. Blumethal M and al. The Complete German Commission E monographs, 1998
2. Natural Medicines Comprehensive Database, Therapeutic Research Faculty, 2007
3. Lininger S. and al. The Natural Pharmacy, Prima Health, 1998
4. Facts and Comparisons, The review of Natural Products, 2000
5. Lexi-comp, Natural Therapeutics Pocket Guide, 2000-2001
6. Passeportsanté.net. Chardon-Marie. http://www.passeportsante.net
7. Barnes J. and al. Herbal Medicines, 2nd edition, Pharmaceutical Press, 2002
8. Herbal Companion to AHFS DI, American Society of Health-System Pharmacists, 2001
9. Rotblatt M. and Ziment I. Evidence-Based Herbal Medicine, Hanley & Belfus, 2002