Milk Thistle

Research Library

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Milk thistle is a popular supplement in Germany, which is where many of the clinical studies on the herb have been performed. It is the most studied herb in the world for liver health, and has been used in traditional medicine for over 2,000 years. The Roman naturalist, Pliny the Elder, even spoke about the beneficial effects in the first century. Silymarin is the active constituent of milk thistle, and it can be found in the plant’s seeds, leaves, and flowers. Found in Europe and the United States, it can be recognized by its beautiful purple flower and sharp spine.

Liver Health

Human Studies

A 1989 study published in the Journal of Hepatology examined the effect on milk thistle on 170 patients with cirrhosis of the liver. It examined the survival rate of patients given milk thistle or a placebo over a 41-month period. The results show a significant improvement in survival rate for milk thistle patients with fewer overall deaths and deaths related to liver disease. Milk thistle was especially effective in patients with alcoholic cirrhosis.

Human studies on milk thistle tend to center around people who are already suffering with liver problems. Some chemotherapy drugs have a damaging effect on the liver; a 2015 study attempted to examine whether milk thistle could help people receiving chemotherapy. The study observed levels of harmful liver-damaging enzymes in a group taking a placebo and a group taking milk thistle. The milk thistle patients exhibited lower levels of liver enzymes detecting damage: SGOT, SGPT, and bilirubin.

Animal Studies

There have been many animal studies performed to try to prove the efficacy of milk thistle. One study on wistar rats showed that milk thistle protects against liver damage. Rats were given CCl4 or CCl4 and milk thistle. The rats given milk thistle group showed a decrease in MDA, a harmful oxidative stress marker in the liver. A mouse study found milk thistle to have a preventative effect against acute liver injury, in part due to its antioxidant and anti-inflammatory properties.


In 2008, a meta-analysis on the effect of milk thistle in liver disease was published in “Research in Complementary Medicine”. The analysis found 19 clinical studies, all of which were double-blind or single-blind human studies. Lower mortality rates, and liver failures were found in the milk thistle patients when compared to placebo; however, results regarding milk thistle’s ability to treat alcoholic liver disease were mixed and inconclusive. Additionally, the researchers determined that milk thistle has no effect on liver disease caused by viral hepatitis.

  1. Milk Thistle impedes the development of carbontetrachlorid-induced liver damage in rats through suppression of bcl-2 and regulating caspase pathway

    Aslan A, Can MI., Life sciences, 2014

  2. Randomized controlled trial of silymarin treatment in patients with cirrhosis of the liver.

    Ferenci P, Dragosics B, Dittrich H, Frank H, Benda L, Lochs H, Meryn S, Base W, Schneider B., Journal of hepatology, 1989

  3. Silymarin (Milk Thistle) can revoke liver enzyme changes during chemotherapy of breast cancer with Taxanes

    Mohaghegh F, Solhi H, and Kazemifar AM. , European journal of integrative medicine, 2015

  4. Silymarin Prevents Restraint Stress-Induced Acute Liver Injury by Ameliorating Oxidative Stress and Reducing Inflammatory Response.

    Kim SH, Oh DS, Oh JY, Son TG, Yuk DY, Jung YS., Molecules, 2016

  5. An updated systematic review with meta-analysis for the clinical evidence of silymarin.

    Saller R, Brignoli R, Melzer J, Meier R., Forsch Komplementärmed, 2008