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Weed Power: Milk Thistle, Liver Disease & the Endocannabinoid System

What do Cannabis and Milk Thistle (Silybum marianum) have in common? Both of these versatile “weeds” have a rich history of medicinal use going back thousands of years. And both convey significant therapeutic benefits that are mediated by the endocannabinoid system.

Indigenous to the Mediterranean region but today found throughout the world, the prickly Milk Thistle is well known among herbalists as a liver tonic and a promoter of kidney and gall bladder health. Considered an invasive plant species in some areas, Milk Thistle has been used by folk healers to treat a wide range of ailments.

Dioscorides, the Greek botanist-physician, in his Materia Medica identified the plant as a remedy for snakebite. Fast forward two millennia: In 2010, Iranian scientists reported that cortisol-lowering Milk Thistle shows promise as a therapy for obsessive-compulsive disorder.

A member of the daisy family, Milk Thistle is also given to under-lactating moms to increase breast milk production. When the white-veined leaves of Milk Thistle are crushed, they exude a milky sap; hence the plant’s name. According to legend, the unctuous white sap is the Virgin Mother’s milk. Today Milk Thistle is one of the top-selling herbs available for purchase in U.S. retail markets.

The main active component of Milk Thistle is silymarin, a well-tolerated, polyphenolic flavonoid complex that lowers insulin resistance and neutralizes health-damaging free radicals. A strong antioxidant, silymarin is also present in artichokes, cilantro and coriander, but Milk Thistle extract is the richest known source of this feisty phytopharmaceutical. Silymarin actually contains three anti-inflammatory components, including silibinin, which inhibits the growth of many types of cancer cells in preclinical research.

Animal studies indicate that silymarin exerts anti-carcinogenic and anti-inflammatory effects on the skin. Topical application of silymarin may provide relief from skin disorders, such as psoriasis, which are indicative of an overtaxed liver. Silymarin can reduce liver toxicity caused by Big Pharma drugs that dermatologists prescribe to treat skin conditions.

Chronic liver disease is a major public health problem throughout the world. An estimated 200 million people, including 3.2 million in the United States, are infected with the Hepatitis C virus, the leading cause of liver failure after cirrhosis. Twenty-five thousand Americans die each year from liver cirrhosis primarily due to alcohol abuse, prescription meds (acetaminophen, for example), and other toxic chemical exposures.

Numerous clinical studies have demonstrated the hepatoprotective properties of Milk Thistle and its positive effects for patients with liver disease. Researchers continue to discover various ways that Milk Thistle is able to improve liver function and mitigate toxic overload. Silymarin stimulates the synthesis of liver-protective bile salts and it alters hepatic cell membrane permeability to prevent toxins from infiltrating and damaging liver cells. Silymarin also increases the body’s production of glutathione, a super-antioxidant that is crucial for liver detoxification. 1

In 2015, a team of Egyptian scientists shed new light on silymarin’s mechanism of action in a study on liver fibrosis in rats. The scientists concluded that silymarin conveys anti-fibrogenic effects by modulating cannabinoid receptor activity in the liver. Both types of cannabinoid receptors, CB1 and CB2 , are expressed in the liver, where they mediate opposing functions. Activating CB1 has a pro-fibrogenic effect; activating CB2 has the opposite effect, reducing fibrosis. Silymarin blocks CB1 while turning on CB2 —a perfect combination for treating hepatic fibrosis and chronic liver disease. The Egyptian study concludes that silymarin “strongly upregulates CB2 expression and downregulates CB1 expression. These effects may be partially responsible for the strong hepatoprotective effect of silymarin.”

Tetrahydrocannabivarin ( THCV ), an intriguing compound unique to the cannabis plant, interacts with the cannabinoid receptors in a similar way, blocking CB1 while boosting CB2 . THCV -rich cannabis would likely benefit people with liver disease by working through some of the same molecular channels as Milk Thistle. Pharmaceutical researchers, meanwhile, are seeking to develop synthetic, receptor-selective drugs that differentially engage both CB1 and CB2 , much like THCV and silymarin.

Liver-Friendly Health Tips

For chronic conditions, Milk Thistle must be taken over an extended period for efficacy, perhaps as long as two years. Several other herbs support liver health, such as yellow dock, chicory, nettle, and all parts of dandelion (roots, leaves, stalks & flowers). Other liver-friendly health tips:

  • Restrict alcohol consumption, avoid Tylenol and acetaminophen.
  • If possible, buy food products in glass, rather than plastic containers to limit your exposure to lipophilic industrial toxins (parabens, phthalates, flame-retardants, BPA and BPS , etc.), which wreak havoc on the liver and the endocannabinoid system.
  • Increase consumption of fermented foods, dark leafy greens and cruciferous vegetables. Other recommended foods include artichokes, garlic, onions, beats, avocados, berries, sprouts, and organic eggs.
  • N-Acetyl L-Cysteine, a potent antioxidant, is an excellent supplement for liver conditions.

Sarah Russo is a contributor to Project CBD , a self-taught lover of herbs, and an avid globetrotter. She is currently based in Granada, Spain.

Copyright, Project CBD . May not be reprinted without permission.

1 It appears that silymarin is less able to repair liver injury and generate new liver cells during the late stages of cirrhosis and hepatitis. Whereas silymarin can reduce liver inflammation, chronic Hepatitis C viral infection may weaken the liver to such an extent that it can’t process silymarin’s constituents for liver repair and regeneration. The extraction of silymarin from Milk Thistle is another factor that may account for inconsistent clinical findings. Silymarin does not include several key components, such as dihydroquercetin, that are present in whole plant Milk Thistle; without these components, silymarin’s efficacy as a therapeutic agent may be compromised.


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  • El Swefy S, Hasan RA , Ibrahim A, Mahmoud MF . Curcumin and hemopressin treatment attenuates cholestasis-induced liver fibrosis in rats: role of CB1 receptors. Naunyn Schmiedebergs Arch Pharmacol. 2016 Jan;389(1):103-16. PubMed PMID : 26475620.
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  • Kalantari H, Shahshahan Z, Hejazi SM , Ghafghazi T, Sebghatolahi V. Effects of silybum marianum on patients with chronic hepatitis C. J Res Med Sci. 2011 Mar;16(3):287-90. PubMed PMID : 22091246; PubMed Central PMCID : PMC3214335 .
  • Kang JS , Yoon WK , Han MH , Lee H, Lee CW , et al. Inhibition of atopic dermatitis by topical application of silymarin in NC /Nga mice. Int Immunopharmacol. 2008 Oct;8(10):1475-80. PubMed PMID : 18593606.
  • Li F, Ma Z, Guan Z, Chen Y, Wu K, et al. Autophagy induction by silibinin positively contributes to its anti-metastatic capacity via AMPK /mTOR pathway in renal cell carcinoma. Int J Mol Sci. 2015 Apr 15;16(4):8415-29. PubMed PMID : 25884331; PubMed Central PMCID : PMC4425089 .
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See also:

  • HerbalGram for Milk Thistle – American Botanical Council
  • Magnificent Milk Thistle – Dr. Mercola, September 14, 2015
  • Nourishing the Liver the Wise Woman Way – Wise Woman Herbal Ezine with Susan Weed, June 2006.
  • A Desktop Guide to Herbal Medicine. Mars, Brigette (2007).

*Cover photo taken by Sarah Russo in Berkeley, California.

Both milk thistle and cannabis convey therapeutic benefits that are mediated by the endocannabinoid system. The active component in milk thistle, silymarin, is responsible for its liver protective qualities and influence both CB1 and CB2 receptors throughout the body.

Does Milk Thistle Help Your Liver?

Articles On Supplements & Your Liver

Supplements & Your Liver
Supplements & Your Liver – Does Milk Thistle Help Your Liver?
  • Milk Thistle for Your Liver
  • Natural Treatment for Hep C
  • How to Keep Your Liver Healthy

Prickly yet pretty, milk thistle is a plant with a long, thin stem, spiny leaves, and a purplish-pink thistle at the top. Often considered a weed, it has been used for hundreds of years as a natural, herbal way to treat liver and gallbladder diseases. But is it really good for you, and can it really help your liver?

What Is Milk Thistle?

This plant is named for the white lines that streak across its green leaves. If the leaves are ripped or crushed, a milky white liquid oozes out. You might also hear it called Mary thistle or holy thistle.

Milk thistle is native to Europe’s Mediterranean region. It now grows all over the world, including northern Africa, South Australia, and parts of North and South America.

It’s sometimes called silymarin, which is one of the main components of the plant’s seeds. The terms milk thistle and silymarin are often used interchangeably, even though they aren’t exactly the same thing.

Silymarin is considered an antioxidant and an anti-inflammatory. In the United States, it’s one of the most commonly used herbal supplements for liver issues.

What Can It Do for the Liver?

Silymarin is said to keep toxins from attaching to liver cells. It also holds free radicals in check. These unstable molecules are byproducts of your body’s functions. But they can harm healthy cells and lead to health issues.

Medical research on milk thistle and liver health has led to mixed results. Studies show that silymarin may helpВ ease inflammation and promote cell repair. This may help ease symptoms from liver diseases like jaundice, cirrhosis, liver cancer, and fatty liver disease.

However, other studies don’t show any effect against another liver disease: hepatitis C, which is a viral infection. A major study found that people with hepatitis C didn’t benefit even from higher-than-normal doses of silymarin. Researchers found no changes in virus levels or quality of life in people who took the milk thistle, compared with those who took a placebo.

So far, no herbal supplement has been proved to be effective against hepatitis C.


While more research is needed in that area, silymarin does have a good track record when it comes to treating a certain kind of mushroom poisoning.

Amanita phalloides is better known as the death cap for good reason. It’s responsible for most of the deaths from eating foraged mushrooms worldwide each year. Eating it can lead to liver damage and even liver failure. But silymarin has been helpful, and at least one clinical trial is underway.

Are There Side Effects?

Generally, it’s safe to take milk thistle in recommended doses. Some people have reported nausea, gas, diarrhea, or loss of appetite. Other people have reported a headache or itchiness after they take it.

Milk thistle can cause an allergic reaction, especially if you’re allergic to other plants in the same family. These include ragweed, daisies, marigolds, and chrysanthemums.

People who have diabetes should talk to their doctor before they take milk thistle because it may lower blood sugar.

Don’t take it if you have breast, uterine, or ovarian cancer; endometriosis; or uterine fibroids. It can mimic estrogen. If you’re pregnant or breastfeeding, talk to your doctor before you take milk thistle or any herbal supplement.

Are There Known Drug interactions?

Talk to your doctor before you take milk thistle. It may affect how some medications work, including

  • Diabetes medications
  • Hepatitis C medications
  • Metronidazole (an antibiotic)
  • Diazepam (Valium)
  • Warfarin (Coumadin, Jantoven)
  • Sirolimus (an immunosuppressant)

How Do You Take Milk Thistle?

Milk thistle comes in powder, capsule, pill, or liquid extract forms. You can make the powder into a tea, blend it into a smoothie, or stir it into water. Swallow the capsule or pill with a glass of water. Add the liquid extract to water or tea.

Always talk to your doctor before you take any herbal supplements.


University of Rochester Medical Center: “Milk Thistle.”

Mayo Clinic: “Milk thistle.”

National Center for Complementary and Integrative Health: “Hepatitis C and Dietary Supplements,” “Milk Thistle.”

Lancet Oncology: “Milk thistle: early seeds of potential.”

Huntington’s Outreach Project For Education, at Stanford: “About Free Radical Damage.”

Journal of Natural Products: “Silymarin Suppresses Cellular Inflammation By Inducing Reparative Stress Signaling.”

Journal of the American Medical Association: “Effect of silymarin (milk thistle) on liver disease in patients with chronic hepatitis C unsuccessfully treated with interferon therapy: a randomized controlled trial.”

Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report: “Amanita phalloides Mushroom Poisonings — Northern California, December 2016.”

News Release, University of California Santa Cruz.

Milk thistle, also known as silymarin, has been used for hundreds of years as an herbal remedy for liver problems. What is it? And can it really help your liver? ]]>