Milk Thistle (Silybum marianum) is an important herb for protecting and maintaining function of
the liver, our largest gland and a powerful organ responsible for multiple metabolic functions and physiological processes.
The liver produces bile, metabolizes carbohydrates, proteins and lipids, stores vitamins and minerals, and filters blood coming from our digestive tract, guiding it back into circulation.2,3
The liver’s main role is to detoxify, destroy disease-causing agents, metabolizing drugs and removing chemicals from our blood stream[1,3]. Liver cells, known as hepatocytes, have the power to regenerate, but this mechanism is impaired when the cells are infected or damaged. Without a properly functioning liver, many biological processes will be compromised, and conditions can be life-threatening.
Milk Thistle seed is curative and protective to hepatocytes, and therefore the liver. Liver disease and impairment is common due to over-indulging and frequent pharmaceutical use. Free-radicals, potentially harmful reactive molecules, are produced from metabolizing toxic substances, including alcohol, acetaminophen (and other medications), and carbon tetrachloride (often found in cleaning products).
These free-radicals damage liver cell membranes by stealing the electrons from the membrane lipids[2,4]. Damage to the liver from free-radicals and other toxic alkaloids and viruses can lead to impairment of the many functions that the liver is meant to perform, and can be harmful to human life[1,3]. Thankfully, nature provides us with what we need to protect our livers and combat the damage we may unknowingly cause ourselves.
Milk Thistle is also anti-inflammatory, anti-viral, antioxidant, and immunomodulating (supports the immune system), which are all actions related to its hepatoprotective quality. Milk thistle seed is also curative to the liver, actively aiding in regeneration of hepatocytes and stimulating the liver’s normal processes, like protein synthesis, enabling the liver function optimally.
When the liver is unable to regenerate its cells due to toxic interference, Milk thistle can stimulate the regeneration process. Thus, Milk thistle seed prevents damage from toxins and facilitates faster repair when damage is done, making it an effective herb in today’s society.
The whole Milk thistle seed includes multiple chemical particles that all act together to provide synergistic therapeutic actions. Though the whole seed has a natural ability to function as one,
its also important we are familiar with the chemical makeup of the plant, so we understand how each constituent biologically functions. Milk thistle seeds are made up of constituents called flavanolignans, fixed oils (oleic and palmitic acid), sterols, and mucilage[3,5].
Most of the research done on this plant focuses on the flavanolignans, collectively called silymarin. Silymarin is a combination of 8 flavanolignans, most notably silybin.
Flavanolignans are natural phenols composed of flavonoids and lignans.
Flavanoids are polyphenol compounds, considered essential nutrients, made up of two benzene rings bound by three atom heterocyclic carbon chains. Flavanolignans are all found to be protective to liver cells, and this is apparent in silymarin.
Silymarin acts in multiple ways to protect and repair the liver, and enhance its functions. It is
considered an antioxidant in defense of the liver because it enhances hepatic glutathione, an
antioxidant critical in protection of liver cells[2,4]. Because it is a phenolic constituent, it donates electrons to stabilize the reactive oxygen of free radicals, thus preventing their damaging action.
Silymarin forms a complex around the hepatocyte and maintains the integrity of the cell
membrane to impede the entrance of toxic substances, including viruses, into the interior of the
cell[4,6]. It also protects the liver cells by stabilizing biological membranes, protecting against gene injury and increasing hepatocyte protein synthesis.
Silymarin assists the liver’s role in protein synthesis by directly stimulating the protein synthesizing enzyme, RNA polymerase 1. Silymarin is not only protecting liver cells, but is chemically combating the damage done by toxins, repairing and rebuilding the hepatocytes, driving the liver more effective.
When there is danger to the cell, silymarin interferes with the cell-cycle-regulators and proteins involved in apoptosis (cell death), helping the cells to survive. Silymarin also is involved in blocking activation of transcription factors in liver cells, decreasing activity of tumour promotors.
Through the therapeutic actions of silymarin, Milk thistle is useful in various conditions, mainly liver disorders or anywhere liver assistance may be needed. Milk thistle is helpful in treating are hepatitis, cirrhosis, and certain cancers[3,4,6]. Whenever potentially damaging chemicals are present in the body, even those we introduce deliberately, including pharmaceuticals, Milk thistle is one of the first herbs I think of to use.
Milk thistle seed, in my opinion, is the best medicine out there for the liver, protecting and even restoring hepatocytes from toxic damage. I use Milk thistle seed frequently in my practice, as it is safely combined with most other medicines and conditions, and is safe and effective in high doses[3,4].
It is easily introduced into a client’s daily routine, as a powder, capsule, or tincture.
I recommend this herb to almost anyone who regularly takes medication, is exposed to
environmental toxins, excessively consumes alcohol or drugs, or has had any sort of potential
(*always consult a Medical Herbalist or Physician if you have any health conditions or are pregnant)
Lauren Truscott Waddell, RHT, CHHC
Picture credit: @photosbyashlenenairn
1. Gould, Barbara (2006). Pathophysiology for the Health Professions. Philadelphia, PA:
2. Vargas-Mendoza, N. et. al. (2014, Mar 27). Hepatoprotective effect of silymarin. World
Journal of Hepatology. 6(3): 144–149. Retrieved from:
3. Hoffmann, David (2003). Medical Herbalism; The Science and Practice of Herbal Medicine.
Rochester, Vermont: Healing Arts Press.
4. Loguercio, C & Festi, D. (2011, May 14). Silybin and the liver: from basic research to clinical
practice. World Journal of Gastroenterology. 17(18): 2288–2301. Retrieved from:
5. Shin, JH & Jung, JH. ( ). Non-alcoholic fatty liver disease and flavanoids: current perspective.
Clinical Research on Hepatology and Gastroenterology. 41(1):17-24. Retrieved from:
6. Polyak, S. J. et al. (2010, Mar 30). Identification of hepatoprotective flavonolignans from
silymarin. Proceedings of the National Academy of Sciences of the United States of America.
107 (13) 5995-5999. Retrieved from: http://www.pnas.org/content/107/13/5995