How does milk thistle work to support liver function and general health? Since Ancient Greece, the plant (Silybum marianum) has been used for liver and gallbladder disorders.
In the 1800s milk thistle was often administered for menstrual and vascular disorders.
Today, the supplement is used for a wide variety of purposes, including allergic rhinitis, depression, liver and kidney disorders, prostate cancer and hangover.
Contemporary research into the therapeutic effects of milk thistle began in the 1970s. It has particularly focused on the supplement’s antioxidant and hepatoprotective (liver protecting) qualities.
Milk thistle extract may work to reduce damage to the liver caused by some forms of toxins, alcohol and oxidative free radicals. However, the best way to support liver function is to prevent these sources of damage from entering the body in the first place.
While the liver protecting actions of S. marianum have been well researched, other potential therapeutic actions are relatively new subjects for clinical study. This article will discuss the mechanisms of action attributed to milk thistle extract and the ways it is commonly used today as a supplement.



- Supports liver health & detox
- Anti-oxidant & anti-inflammatory properties
- Improves insulin sensitivity & cholesterol
Does Milk Thistle Work?
Related Topics
- Milk Thistle
- Silybum Marianum
- Silymarin
- Benefits & Uses
- User Reviews
- Use for Diabetes
- Use for Hangovers
- Use for Psoriasis
- Use for Liver Health
- Use for Weight Loss
- Milk Thistle Tea
- Milk Thistle Extract
- Dosage Guide
- How to Take
- Reported Side Effects
- Safe Usage
- Best Supplements
- Combo with Dandelion Extract
- Milk Thistle Tincture
Milk Thistle has a long history of traditional use as a detoxifying agent. The seeds of this herb contains a flavonoid complex called “silymarin”.
Silymarin is believed to be the active component of Milk Thistle extract; most of the mechanisms of action for this herb are attributed to this flavonoid complex.
In research studies, milk thistle extract has found to improve liver function tests, help control blood sugar levels, reduce menopause symptoms and improve symptoms of dyspepsia. It is also used to improve skin health and as a general anti-aging supplement.
We know that components of milk thistle work to limit the damage to the liver after exposure to certain forms of toxins. In preliminary trials, it also is showing some promise as an anti-diabetic, cardioprotective, renoprotective, antioxidant and anti-inflammatory agent.
It has been hypothesized that milk thistle extract may work against some cancer cell lines. While there have been promising results in laboratory studies, clinical research is lacking to indicate whether or not these same effects will take place in the human body.
Studies of milk thistle have often focused on its use as a complement to conventional treatments (such as in studies of allergic rhinitis or diabetes). This is opposed to a replacement or alternative to conventional therapies.
In the following sections, we will discuss the research regarding the mechanisms of silymarin and milk thistle extract for liver health, diabetes and cancer. These are three of the most active areas of research into this herbal extract.
Milk Thistle and Liver Function
Several studies indicate milk thistle may help in addressing symptoms of cirrhosis (scarring) of the liver. In studies lasting as long as 60 months, milk thistle supplementation has been observed to enhance overall liver function and reduce the mortality rate of patients with liver disease.
Also, S. marianum has been observed to improve the symptoms of chronic liver disease caused by either virus or excessive alcohol consumption.
Milk thistle has been observed to act against viral hepatitis and/or virus-induced liver inflammation. Further, animal studies indicate milk thistle may lower LDL (so-called “bad”) cholesterol production.
Finally, milk thistle may work to protect against liver damages incurred by exposure to toxic environmental chemicals, and may help reduce the effects of pre-existing exposure.
Although many studies relating to the liver protecting and repairing qualities of milk thistle have been conducted, the current state of research is not conclusive. Further standardized clinical trials are warranted.
Milk Thistle for Type II Diabetes?
Clinical research indicates milk thistle may be helpful as a complement to conventional therapy for Diabetics. Milk thistle has been observed to reduce symptoms of type II diabetes mellitus and/or diabetic nephropathy.
S. marianum has also demonstrated hypolipidemic (lipid-lowering) and hypoglycemic (blood-sugar-lowering) properties. Research continues to indicate that milk thistle helps lower blood sugar levels in patients with type II diabetes (in conjunction with conventional treatment).
Milk thistle has also been observed to reduce urine and blood markers indicative of diabetic kidney disease.
Milk Thistle and Cancer
Research into the anticancer effects of milk thistle is in the preliminary stages.
One of the most attractive characteristics of the plant to cancer researchers is its apparent antioxidant activity. S. marianum possesses properties that suggest it may help increase antioxidant levels in blood plasma.
In preclinical studies, milk thistle has been observed to significantly increase the levels of the antioxidant superoxide dismutase (SOD). SOD helps reduce free radical damage and is one of the most prevalent antioxidant in the human body.
Silybin, a constituent of S. marianum, has demonstrated in-vitro and in-vivo actions against some cancer cell cells. Silybin’s observed anticancer effects may be caused by its interruption of important cancer cell signaling pathways, particularly the suppression of STAT3 (signal transducers and activators of transcription pathways 3).
STAT3 moderates a number of pathways that are important for cancer cell progression, which includes angiogenesis, invasion, metastasis and apoptosis. Suppressing STAT3 may compromise the ability of tumors to grow and spread.
Recent research also indicates that silybin supplementation reduces toxic skin reactions after radiation treatments in breast cancer patients.
Further Uses for Milk Thistle Extract
Milk Thistle is used for a number of additional health indications. Many of these additional uses have not yet received sufficient clinical research attention, but may be supported by the ways that Milk Thistle is traditionally thought to work.
Some of these uses include:
- Supporting fertility in women, especially when undergoing in-vitro fertilization (IVF);
- Alleviating heartburn;
- Decreasing the prevalence of menopausal symptoms;
- Treating painful PMS symptoms;
- Improving the cognitive function of patients with neurodegenerative disorders, including Parkinson’s, Alzheimer’s and multiple sclerosis;
- Easing the symptoms of obsessive compulsive disorder;
- Decreasing pain associated with osteoporosis and osteoarthritis via anti-inflammatory activity;
- Decreasing the severity of allergic reactions, especially nasal symptoms;
- Treating Amanita phalloides (Death Cap) mushroom poisoning.
Silybum marianum supplementation has also been used for asthma, biliary colic, bleeding, constipation, depression, weight loss, hemochromatosis, hemorrhoids, gestational hypertension, hyperthyroidism, psoriasis, snakebites, uterine disorders, varicose veins and vasculitis.
Is Milk Thistle Safe to Use?
Milk thistle is generally well tolerated when used properly. Studies indicate this supplement may be safe for long-term use up to 44 months. Mild and temporary side effects may include headache and upset stomach.
Because of the way that milk thistle works in the liver, it may interact with drugs or supplements that are metabolized by the liver. A number of common pharmaceuticals used today fall into this category. Milk thistle may affect the way these drugs work by either increasing or decreasing their bioavailability.
Use cautiously if you are taking Cytochrome p450 substrate medications and/or antidiabetic medications. Other drug interactions are possible. Speak with your doctor before beginning Silybum marianum supplementation.
- Kazazis CE, Evangelopoulos AA, Kollas A, Vallianou NG. The therapeutic potential of milk thistle in diabetes. Rev Diabet Stud. 2014 Summer;11(2):167-74.
- Bosch-Barrera J, Menendez JA. Silibinin and STAT3: A natural way of targeting transcription factors for cancer therapy. Cancer Treat Rev. 2015 Jun;41(6):540-6.
- Huang C, Huang R, Chang W, Jiang T, Huang K, Cao J, Sun X, Qiu Z. The expression and clinical significance of pSTAT3, VEGF and VEGF-C in pancreatic adenocarcinoma. Neoplasma. 2012;59(1):52-61.
- Ebrahimpour Koujan S, Gargari BP, Mobasseri M, Valizadeh H, Asghari-Jafarabadi M. Effects of Silybum marianum (L.) Gaertn. (silymarin) extract supplementation on antioxidant status and hs-CRP in patients with type 2 diabetes mellitus: a randomized, triple-blind, placebo-controlled clinical trial. Phytomedicine. 2015 Feb 15;22(2):290-6.
- Deep, Gagan et al. "Angiopreventive Efficacy of Pure Flavonolignans from Milk Thistle Extract against Prostate Cancer: Targeting VEGF-VEGFR Signaling." Ed. Surinder K. Batra. PLoS ONE 7.4 (2012): e34630. PMC. Web. 10 Aug. 2015.
- Post-White J, Ladas EJ, Kelly KM. Advances in the use of milk thistle (Silybum marianum). Integr Cancer Ther. 2007 Jun; 6(2):104-9.
- Brantley, Scott J. et al. "Two Flavonolignans from Milk Thistle (Silybum Marianum) Inhibit CYP2C9-Mediated Warfarin Metabolism at Clinically Achievable Concentrations." The Journal of Pharmacology and Experimental Therapeutics 332.3 (2010): 1081–1087.
- Rosso N, Marin V, Giordani A, Persiani S, Sala F, Cavicchioli L, Rovati LC, Tiribelli C. The pros and the cons for the use of Silybin-rich oral formulations in treatment of liver damage (NAFLD in particular). Curr Med Chem. 2015 Jul 29.
- Abenavoli L Non-alcoholic fatty liver disease and beneficial effects of dietary supplements. World J Hepatol. 2015 Jun 28;7(12):1723-4.
- Bosch-Barrera J, Menendez JA. Silibinin and STAT3: A natural way of targeting transcription factors for cancer therapy. Cancer Treat Rev. 2015 Jun;41(6):540-6.
Article last updated on: April 1st, 2018 by Nootriment