Blackmores Institute

<h3>Key highlights</h3><ul><li>Milk thistle (Silybum marianum) and its extract, silymarin, are traditionally used to support and protect liver function, especially during times of dietary excess and high alcohol intake.</li><li>Research shows milk thistle benefits extend beyond liver health, with evidence of improvements in cholesterol, metabolic dysfunction-associated fatty liver disease, insulin resistance, obesity, and overall cardiovascular health.</li><li>Silymarin is generally safe and well-tolerated.</li><li>For maximum benefit, silymarin should be used as early as possible in patients with fatty liver disease when the regenerative potential of the liver is still high.</li></ul><h3> Introduction</h3>Milk thistle (Silybum marianum), a traditional herbal remedy, is gaining renewed attention for its potential to support liver function and improve cardiometabolic outcomes, including dyslipidaemia, metabolic dysfunction-associated fatty liver disease (MAFLD), obesity, insulin resistance, and cardiovascular health.1–3<h3> History and key actions of milk thistle</h3>Milk thistle has been used for over 2,000 years for liver and gallbladder disorders.4 Its main active compound, silymarin, is a complex of flavonolignans with potent antioxidant and anti-inflammatory properties.5 Silymarin and its key component, silybin, are recognised for their hepatoprotective effects, helping to protect hepatocytes from toxins and oxidative stress (see Figure 1).1,6,7
<img src="https://images.contentstack.io/v3/assets/blt948bd74310fc0ad0/bltcb32e4018039fc8d/69f296d0207e6912553c5033/bi-milk-thistle-from-liver-support-to-metabolic-balance-figure1.jpg" alt="bi-milk-thistle-from-liver-support-to-metabolic-balance-figure1.jpg" class="embedded-asset" />Figure 1: The hepatoprotective effects of silymarin.7<h3> Supporting liver health with milk thistle</h3>The hepatoprotective action of milk thistle is well-documented, with studies showing its role in supporting liver cell regeneration and liver fibrosis and fatty liver protection.4,5,8–14 A 2025 meta-analysis of randomised controlled trials (RCTs = 55; n = 3,545) demonstrated significant reductions in key liver enzymes (AST, ALT), particularly in patients with MAFLD, which often coexists with obesity and poor diet.15<h3> Table 1: Silymarin actions to promote liver health</h3><table><tbody><tr><th>Action</th><th>Description</th></tr><tr><td>Antioxidant</td><td> • Inhibits lipid peroxidation and reduces oxidative stress produced during liver detoxification and everyday metabolic reactions.2,15
 • Acts as a free radical scavenger, helping the liver to maintain its key antioxidant glutathione, which protects the liver, increasing detoxification capacity.15–17 </td></tr><tr><td>Antitoxin and hepatoprotective</td><td> • Protects against liver injury from various toxic chemicals (including alcohol) by inhibiting toxins from binding to hepatocyte cell membrane receptors.18
 • Inhibits beta-glucuronidase and prevents the production of reactive and toxic metabolites in the liver and intestines.15
 • Reduces oxidative stress and cytotoxicity, preventing cellular damage and liver injury, especially for intact liver cells or those not irreversibly damaged.8,11 </td></tr><tr><td>Anti-inflammatory and immunomodulatory</td><td> • Inhibits the production of pro-inflammatory mediators like nuclear factor kappa B (NF-κB) and prostaglandin E2 (PGE2), which influence immune regulation in inflammatory states.
 • Reduces nitric-oxide synthase (iNOS) and cyclooxygenase (COX)-2 expression.7,19 </td></tr><tr><td>Antifibrotic</td><td> • Has antifibrogenic effects by inhibiting growth factor and alcohol-induced production of collagen in the liver.4 </td></tr><tr><td>Hepato-trophorestorative (liver-regenerating)</td><td> • Promotes liver cell regeneration by stimulating protein synthesis, stabilising cell membranes, and inhibiting myofibroblast formation (responsible for collagen fibre deposits, further progressing liver injury).4,9
 • Enhances superoxide dismutase activity, supporting protein synthesis that protects and regenerates liver cells.17 </td></tr></tbody></table><h3> Prescribing milk thistle</h3>Early introduction of milk thistle in liver disease, including fatty liver and acute liver failure, may provide the most therapeutic benefit. Research suggests its efficacy is greatest in patients with higher liver regenerative potential and reduced oxidative stress, where silymarin helps limit progression and protect remaining healthy hepatocytes.8The recommended daily dose of silymarin is between 420 mg and 600 mg, with clinical trial doses ranging from 80 mg to 1,600 mg.7 A recent meta-analysis showed greater treatment outcomes with lower doses (&lt; 400 mg) and duration (&lt; 2 months) compared to high doses and longer treatment durations.15 Patients with alcoholic liver disease (ALD) and viral hepatitis have shown significantly reduced liver enzyme levels at doses of 240 and 360 mg/day.7<h3>Beyond the liver: cardiometabolic benefits</h3>In addition to its hepatoprotective effects, milk thistle has also demonstrated cardiometabolic benefits, including improvements in:<ul><li>Cholesterol and lipid profiles: Milk thistle has demonstrated lipid-lowering effects, helping to improve cholesterol profiles by reducing total cholesterol, triglycerides, and LDL cholesterol, while increasing HDL cholesterol. These effects may be attributed to silymarin’s ability to block cholesterol production (by inhibiting the HMG-CoA enzyme), reduce liver triglyceride synthesis, increase mitochondrial beta-oxidation of fatty acids, and inhibit cholesterol absorption in the intestine.18,20,21</li><li>Insulin resistance: Silymarin has been shown to lower fasting blood glucose, insulin, and HbA1c (a marker of long-term glucose control), particularly in those with type 2 diabetes, metabolic syndrome, or obesity. Multiple RCTs have reported improved insulin sensitivity and lower markers of insulin resistance like HOMA-IR.3,20,22</li><li>Cardiovascular health: Beyond its effects on lipid and glycaemic control, milk thistle may offer direct cardioprotective benefits. Silymarin has been shown to lower diastolic blood pressure, regulate vascular tone, and suppress platelet aggregation, likely due to its antioxidant, anti-inflammatory, antifibrotic, and anti-atherogenic properties.1,3,18,23 Large-scale clinical studies are required to further demonstrate these effects.</li></ul><h3> Clinical application and safety</h3>Clinical evidence indicates that milk thistle is generally safe and well-tolerated. Reported adverse effects are uncommon, with headache and skin itching being the most frequent, and gastrointestinal symptoms such as nausea or diarrhoea occurring less often.9,10<h3> Conclusion</h3>Milk thistle is a well-tolerated herb with strong evidence supporting its liver-protective effects and emerging benefits for cardiometabolic health, including improvements in dyslipidaemia, insulin resistance and hypertension. These effects are attributed to silymarin’s hepatoprotective, anti-inflammatory, and antioxidant properties. Recent clinical studies have shown that early introduction and lower doses administered over a shorter period yield the best outcomes. Milk thistle offers a valuable option to support natural detoxification pathways and maintain overall metabolic balance.<a href="/education/ingredient-information-sheets/fact-sheets/milk-thistle" target="_self" style="">For a full prescribing guide, view our ingredient fact sheet.</a> <h3> References </h3><ol><li>Bijak M. Silybin, a Major Bioactive Component of Milk Thistle (Silybum marianum L. Gaernt.)—Chemistry, Bioavailability, and Metabolism. Molecules. 2017 Nov 10;22(11):1942.</li><li>Di Costanzo A, Angelico R. Formulation Strategies for Enhancing the Bioavailability of Silymarin: The State of the Art. Molecules. 2019 June 7;24(11):2155.</li><li>Mohammadi S, Asbaghi O, Afrisham R, Farrokhi V, Jadidi Y, Mofidi F, et al. Impacts of Supplementation with Silymarin on Cardiovascular Risk Factors: A Systematic Review and Dose–Response Meta-Analysis. Antioxidants. 2024 Mar 24;13(4):390.</li><li>Abenavoli L, Izzo AA, Milić N, Cicala C, Santini A, Capasso R. Milk thistle: A concise overview on its chemistry, pharmacological, and nutraceutical uses in liver diseases. Phytother Res. 2018 Nov;32(11):2202–13.</li><li>Surai P. Silymarin as a Natural Antioxidant: An Overview of the Current Evidence and Perspectives. Antioxidants. 2015 Mar 20;4(1):204–47.</li><li>Zare Mehrjerdi P, Asadi S, Ehsani E, Askari VR, Baradaran Rahimi V. Silibinin as a major component of milk thistle seed provides promising influences against diabetes and its complications: a systematic review. Naunyn Schmiedebergs Arch Pharmacol. 2024 Oct;397(10):7531–49.</li><li>Tighe SP, Akhtar D, Iqbal U, Ahmed A. Chronic Liver Disease and Silymarin: A Biochemical and Clinical Review. J Clin Transl Hepatol. 2020 Dec 28;8(4):1–5.</li><li>Gillessen A, Schmidt HHJ. Silymarin as Supportive Treatment in Liver Diseases: A Narrative Review. Adv Ther. 2020 Apr;37(4):1279–301.</li><li>Hackett ES, Twedt DC, Gustafson DL. Milk Thistle and Its Derivative Compounds: A Review of Opportunities for Treatment of Liver Disease. J Vet Intern Med. 2013 Jan;27(1):10–6.</li><li>Jaffar HM, Al‐Asmari F, Khan FA, Rahim MA, Zongo E. Silymarin: Unveiling its pharmacological spectrum and therapeutic potential in liver diseases—A comprehensive narrative review. Food Sci Nutr. 2024 May;12(5):3097–111.</li><li>Mirhashemi SH, Hakakzadeh A, Yeganeh FE, Oshidari B, Rezaee SP. Effect of 8 Weeks milk thistle powder (silymarin extract) supplementation on fatty liver disease in patients candidates for bariatric surgery. Metab Open. 2022 June;14:100190.</li><li>Qurban A, Khan H, Ali F, Abbas S, Hameed SA, Hussain N. Determine the Curing Effects of Silybum marianum (milk thistle) Administered Orally to Non-Alcoholic Fatty Liver Disease (NAFLD) Patients for Six Months: Curing Effects of Silybum marianum. Pak Biomed J. 2023 Apr 30;27–30.</li><li>Valková V, Ďúranová H, Bilčíková J, Habán M. Milk thistle (silybum marianum): a valuable medicinal plant with several therapeutic purposes. J Microbiol Biotechnol Food Sci. 2020 Feb 3;9(4):836–43.</li><li>Zhong S, Fan Y, Yan Q, Fan X, Wu B, Han Y, et al. The therapeutic effect of silymarin in the treatment of nonalcoholic fatty disease: A meta-analysis (PRISMA) of randomized control trials. Medicine (Baltimore). 2017 Dec;96(49):e9061.</li><li>Shahsavari K, Ardekani SS, Ardekani MRS, Esfahani MM, Kazemizadeh H, Jamialahmadi T, et al. Are alterations needed in Silybum marianum (Silymarin) administration practices? A novel outlook and meta-analysis on randomized trials targeting liver injury. BMC Complement Med Ther. 2025 Apr 12;25(1):134.</li><li>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;22(2):290–6.</li><li>Mohammadi SM, kianbakht S, Rezazadeh S, Ziaee M, Fallah Huseini H. Clinical efficacy of Silybum marianum seed extract in treatment of type 2 diabetes mellitus and non-alcoholic fatty liver disease: a narrative review. jmpir. 2020 Mar 1;19(73):12 EP – 26.</li><li>Kadoglou NPE, Panayiotou C, Vardas M, Balaskas N, Kostomitsopoulos NG, Tsaroucha AK, et al. A Comprehensive Review of the Cardiovascular Protective Properties of Silibinin/Silymarin: A New Kid on the Block. Pharmaceuticals. 2022 Apr 27;15(5):538.</li><li>Zhao Y, Zhou Y, Gong T, Liu Z, Yang W, Xiong Y, et al. The clinical anti-inflammatory effects and underlying mechanisms of silymarin. iScience. 2024 Nov;27(11):111109.</li><li>Tajmohammadi A, Razavi BM, Hosseinzadeh H. Silybum marianum (milk thistle) and its main constituent, silymarin, as a potential therapeutic plant in metabolic syndrome: A review. Phytother Res. 2018 Oct;32(10):1933–49.</li><li>De Freitas JA, Santamarina AB, Otoch JP, Pessoa AFM. Silymarin: A Natural Compound for Obesity Management. Obesities. 2024 Aug 9;4(3):292–313.</li><li>MacDonald-Ramos K, Michán L, Martínez-Ibarra A, Cerbón M. Silymarin is an ally against insulin resistance: A review. Ann Hepatol. 2021 July;23:100255.</li><li>Taleb A, Ahmad KA, Ihsan AU, Qu J, Lin N, Hezam K, et al. Antioxidant effects and mechanism of silymarin in oxidative stress induced cardiovascular diseases. Biomed Pharmacother. 2018 June;102:689–98.</li></ol>

Milk thistle (Silybum marianum), long recognised for its liver-supporting properties, is backed by growing clinical evidence showing benefits for both liver function and cardiometabolic balance, making it a valuable natural option to support health during times of overindulgence.

Recommended for you

Psychoneuroimmunology | Connecting the mind, brain, gut, and immune system

Supporting urinary tract health

Blueberries the well known super fruit could help fight Alzheimer's

Algae Oil | The original omega-3 source