Milk thistle: benefits, dosage, contraindications

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Milk thistle, from the Asteraceae family, is easily recognizable by its pale green leaves marbled with white, shiny and spiny, its pink-purple flowers, and its large size often exceeding 1 meter. It owes its name to a legend: a drop of milk from the Virgin Mary is said to have left a white mark on the plant's leaves. Native to the Mediterranean basin, milk thistle thrives in dry and sunny lands up to 700 meters in altitude. It can be found throughout Western and Central Europe, North Africa, and the Middle East. The fruit is a black achene, and the part used in herbal medicine is the fruit deprived of its bristles. In dietary supplements, the active substance of milk thistle is found: silymarin. Also found in the fruit are: flavonoids, sterols, and oils. Among the traditionally recognized properties of this plant are relief from digestive disorders linked to insufficient bile production, and liver diseases.

Other name(s) 

Silymarin, Wild Artichoke

Scientific name(s)

Carduus marianus, Silybum marianum

Family or group: 

Plants

Active ingredients:

Silymarin

Betaine

Mucilage

Flavonoids

Sterols


Indications

Rating methodology

EFSA approval.

Several clinical trials (> 2) randomized controlled with double blind, including a significant number of patients (>100) with consistently positive outcomes for the indication.
Several clinical trials (> 2) randomized controlled with double blind, and including a significant number of patients (>100) with positive outcomes for the indication.
One or more randomized studies or multiple cohorts or epidemiological studies with positive outcomes for the indication.
Clinical studies exist but are uncontrolled, with conclusions that may be positive or contradictory.
Lack of clinical studies to date that can demonstrate the indication.


Type 2 Diabetes
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Clinical studies have shown that taking milk thistle extract containing silymarin at 140 mg three times a day for 45 days can reduce fasting blood glucose by 11% and insulin by 14%, and improve insulin resistance. There were also improvements in high-density lipoprotein (HDL) cholesterol levels, but not in low-density lipoprotein (LDL) or total cholesterol, compared to placebo.

Posologie

posologieOrally: fruit

posologie140 - 420 mg

duration3 - months

populationAdults

formulationmother tincture, standardized extract


Biliary disorders
✪✪✪✪✪

Milk thistle is traditionally used to relieve digestive disorders associated with insufficient bile production. Silymarin is poorly soluble in water. As a result, water-based product preparations such as herbal teas are ineffective. For oral use, the product should be concentrated. Commission E and the World Health Organization recognize the use of milk thistle in cases of dyspepsia.

Posologie

posologieOrally: fruit, aerial parts

posologie125 - 630 mg

populationAdults

formulationstandardized extract


Liver disorders
✪✪✪✪✪

Silymarin protects the liver through different mechanisms. It allows for stabilization of the plasma membrane of the hepatocyte. It inhibits the absorption of certain toxins by preventing their attachment to the cell surface and by blocking the membrane transport system of these poisons. Furthermore, it traps numerous free radicals by forming more stable and less reactive compounds. It also contributes to maintaining the level of glutathione and superoxide dismutase in the liver. In vitro, it increases the synthesis of hepatocyte proteins through stimulation exerted on RNA polymerase 1, which is involved in the synthesis of ribosomal RNA, thereby contributing to increasing the liver's regeneration capacities.

Posologie

posologieOral route: fruit

duration4 - weeks


Alzheimer's Disease
✪✪✪✪✪

Preliminary clinical research shows that taking a supplement containing 150 mg of silymarin extract (milk thistle) in combination with ferulic acid, gamma-oryzanol, and apigenin orally twice a day for 3 months to 2 years can stabilize the mental function of patients with Alzheimer's disease.

Posologie

posologieOral route: fruit

posologie300 mg

duration3 - months

populationAdults

formulationdry extract


Synergies


Acne
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A small clinical trial in patients with acne vulgaris shows that taking 140 mg of silymarin orally daily for 2 months is effective in reducing the severity of acne. However, the use of silymarin in combination with doxycycline does not appear to be more effective than doxycycline alone.

Posologie

posologieOral route: fruit

posologie140 mg

duration2 - months

populationAdults

formulationstandardized extract


Hypercholesterolemia
✪✪✪✪✪

A meta-analysis of three clinical trials shows that taking a specific product containing 105 mg of milk thistle and turmeric extract twice a day for 3 months, along with diet and exercise, reduces LDL cholesterol levels compared to diet and exercise alone in hypercholesterolemic patients. There was no effect on HDL cholesterol or triglyceride levels. It is unclear whether the effects of this product are due to the milk thistle extract, turmeric extract, or the combination.

Posologie

posologieOral route: fruit

posologie210 mg

duration3 - months

populationAdults

formulationdry extract


Synergies


Hepatic Steatosis
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Clinical research in patients with non-alcoholic steatohepatitis shows that taking a milk thistle extract of 700 mg of silymarin three times a day for 48 weeks improves fibrosis compared to placebo.

Posologie

posologieOral route: fruit

posologie2100 mg

duration48 - weeks

populationAdults

formulationsilymarin


Parkinson's Disease
✪✪✪✪✪

Clinical research shows that taking a supplement containing a milk thistle extract with 150 mg of silymarin in combination with ferulic acid, gamma-oryzanol, and apigenin orally twice a day for 3 months to 24 months can stabilize the clinical symptoms of Parkinson's disease in affected patients.

Posologie

posologieOral route: fruit

posologie300 mg

duration24 - months

populationAdults

formulationsilymarin


Synergies


Cirrhosis
✪✪✪✪✪

Preliminary clinical research explains that daily intake of milk thistle extract at 420 mg of silymarin orally for 4 years may improve liver function and reduce mortality in people with cirrhosis.

Posologie

posologieOral route: fruit

posologie420 mg

duration4 - years

populationAdults

formulationsilymarin


Hepatitis
✪✪✪✪✪

In people with hepatitis, regardless of the cause, taking an extract of 140 mg of milk thistle containing 70% to 80% silymarin orally three times a day for 4 weeks improves some symptoms, such as jaundice and dark urine, but doesn't improve liver enzymes. A double-blind randomized study including 57 patients with acute hepatitis A or B, and treated daily with 420 mg of silymarin for 3 weeks, shows normalization of biochemical parameters (bilirubin, transaminases), reduced hospital stays, faster immunity development, and reduced complications associated with infection in the treated group. In chronic hepatitis cases, treatment with 420 mg of silymarin per day for 3 to 12 months improves histological parameters, without influencing biological or functional markers. However, the analysis of clinical research concludes that any clinical effect of milk thistle in people with viral hepatitis is limited, but most results show that milk thistle has no significant effect on mortality, liver disease complications, or liver histology.

Posologie

posologieOral route: fruit

posologie420 mg

duration4 - weeks

populationAdults

formulationsilymarin, dry extract


Detoxification
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In humans, milk thistle does not have a significant effect on CYP3A4, although in vitro, silybin inhibits phase I metabolic pathway activity (Cytochromes CYP3A4 and CYP2C9). Silymarin also increases glucuronidation (phase II detoxification reaction). Furthermore, silymarin is the only known medication that effectively protects against the Amanita phalloides toxin, which targets the liver, in combination with N-acetylcysteine.

Posologie

posologieOral route: fruit

formulationsilymarin


Synergies


Chemotherapy
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Silymarin appears to enhance the efficacy of certain anticancer treatments by potentiating their cytotoxicity while simultaneously, sometimes, reducing their toxicity on healthy tissues. In vitro studies on different cell types show a synergy between silymarin and various anticancer drugs (temozolide, etoposide, irinotecan in glioma, doxorubicin in breast cancer). Other research suggests that silymarin can mitigate the side effects of cancer treatments: in women with breast cancer, applying a product containing a silymarin extract reduces the incidence of radiation dermatitis and prolongs the delay of its appearance compared to applying a cream containing panthenol. Preliminary clinical research conducted on cancer patients receiving radiotherapy for the first time shows that taking a product containing a silymarin extract, from the first day of radiotherapy and for the following 6 weeks, reduces the severity and prolongs the delay of the appearance of radiation-induced mucositis compared to a placebo. As part of an integrative approach, in addition to anticancer treatment, the use of milk thistle is recommended, notably by the "Clinical practice committee of the society of integrative oncology".

Posologie

posologieOral: fruit

posologie420 mg

duration6 - weeks

formulationsilymarin


Digestive disorders
✪✪✪✪

The EMA recognizes the traditional use of milk thistle preparations for the relief of dyspepsia and digestive disorders of hepatic origin, after the exclusion of serious illnesses.

Posologie

posologieOral: fruit

posologie300 - 600 mg

formulationdry extract


Metabolic syndrome
✪✪✪✪

In relation to its actions on metabolism: see hypoglycemic and hypolipidemic properties.

Posologie

posologieOral: fruit

formulationsilymarin


Properties


Cholagogue

full-leaffull-leaffull-leaffull-leaf

The silymarin in milk thistle is a very beneficial substance in the treatment or prevention of gallstones. It promotes bile flow by increasing its solubility. Indeed, studies have shown that taking milk thistle caused a reduction in cholesterol in bile. Every time the bile flow is increased, the chances of developing gallstones are lowered.

Usages associés

Biliary disorders

Digestive effect

full-leaffull-leaffull-leafempty-leaf

Milk thistle is traditionally used to relieve digestive disorders associated with insufficient bile production. In Europe, this plant is part of several pharmaceutical preparations containing bitter substances intended for the treatment of various digestive disorders of hepatic and biliary origin.

Usages associés

Digestive disorders

Hepatoprotective

full-leaffull-leaffull-leafempty-leaf

Silymarin protects the liver through various mechanisms. It stabilizes the plasma membrane of the hepatocyte. It inhibits the absorption of certain toxins by preventing their attachment to the cell surface and blocking the membrane transport system of these poisons. Moreover, it traps many free radicals via the formation of more stable and less reactive compounds. It also contributes to maintaining the glutathione level and superoxide dismutase in the liver. In vitro, it increases the synthesis of hepatocyte proteins thanks to the stimulation it exerts on RNA polymerase 1 which is involved in the synthesis of ribosomal RNA, thus contributing to increasing the liver's regeneration capacity.

Usages associés

Hepatic steatosis, Cirrhosis, Hepatitis, Detoxification, Liver disorders

Antioxidant

full-leaffull-leaffull-leafempty-leaf

Silybin reduces lipid peroxidation in various types of cell cultures and in an animal model. It also prevents the depletion of glutathione and protects DNA from degradation.


Hypoglycemic

full-leaffull-leafempty-leafempty-leaf

Silymarin appears to decrease insulin resistance and have a protective effect on the pancreas during in vivo experiments. Silymarin or isosilybin A reduce insulin resistance, in part through agonist action of the PPAR receptor (a key regulator of glucose and lipid metabolism). In vivo, modulation of insulin resistance was observed by increased expression of PTEN (phosphatase and tensin homolog), regulating important cellular functions. Furthermore, the use of silymarin is of interest for diabetic complications, such as diabetic nephropathy, which is caused by oxidative stress and inflammation. The protective effect on the kidney has been demonstrated in vivo: reduction in biochemical parameters (blood glucose, glycated hemoglobin (Hb), urinary volume, uricemia, albuminuria) and histological improvement after 2 months of treatment with 60 to 120 mg/kg of silymarin.

Usages associés

Type 2 Diabetes, Metabolic syndrome

Hypolipidemic

full-leaffull-leafempty-leafempty-leaf

In human research, it has been demonstrated that silymarin lowers total cholesterol (TC), triglycerides (TG), and LDL cholesterol levels. Indeed, milk thistle can inhibit cholesterol acyltransferase, resulting in a reduction of cholesterol absorption and lipoprotein biosynthesis. Moreover, silymarin inhibits HMG-CoA reductase, an enzyme involved in cholesterol metabolism. Milk thistle also decreases the synthesis of very low-density lipoproteins (VLDL) and the amount of free VLDL that can be secreted in the intestine. Furthermore, by decreasing certain factors such as peroxisome proliferator-activated receptor gamma (PPAR gamma), a transcription factor involved in glucose-lipid metabolism regulation, Milk thistle reduces lipid accumulation.

Usages associés

Hypercholesterolemia

Anti-inflammatory

full-leaffull-leafempty-leafempty-leaf

In vitro, in various lines, silymarin reduces the inflammation mediators TNF-B1, NO, and IL-6. Similarly, it blocks the expression of NF5B (nuclear factor-kappa B), a protein involved in immune response and cellular stress response. In Küpffer cells (liver macrophages), silybin inhibits leukotriene production. In an animal model of hepatic ischemia/reperfusion, a milk thistle extract significantly reduces, dose-dependently, serum concentrations of inflammatory cytokines and hepatic enzymes (AST, ALT). Finally, in B2-pancreatic cells, silymarin inhibits the production of NO (nitric oxide) by inducible NO-synthase from inflammatory cytokines.

Usages associés

Acne, Chemotherapy

Neurological

full-leafempty-leafempty-leafempty-leaf

Through its ability to inhibit oxidative stress in the brain and modulate pathways such as B2-amyloid peptide aggregation, inflammatory mechanisms, apoptotic cellular machinery, and estrogen receptor mediation, silymarin holds potential as a neuroprotective agent. It also presents an antidepressant effect partly linked to its action on nitric oxide production. Furthermore, silybin acts on two Alzheimer's disease mechanisms: inhibition of acetylcholinesterase and B2-amyloid peptide aggregation.

Usages associés

Alzheimer's disease, Parkinson's disease

Anti-aging

full-leafempty-leafempty-leafempty-leaf

Thanks to its anti-inflammatory and antioxidant potential, milk thistle proves effective in combating aging. It reduces oxidative damage and mitochondrial dysfunctions in aging mice. Silymarin increases average lifespan, improves locomotion capacity, response to stimuli, and stress tolerance in an animal model.


Safety dosage

Adult from 18 years: 600 mg - 1800 mg (dry extract)


Interactions

Médicaments

Antidiabetic: moderate interaction

Clinical research has shown that milk thistle extract, alone or combined with turmeric extract, can lower blood glucose and hemoglobin A1c (HbA1c) in patients with type 2 diabetes, including those already taking antidiabetics. Theoretically, this reduction could increase the risk of hypoglycemia in patients treated with antidiabetics. Dosage adjustments of antidiabetic medications may be necessary.

Estrogens: minor interaction

Animal research suggests that a silymarin extract from milk thistle binds to the beta-estrogen receptor. Thus, milk thistle could interfere with estrogens by a competitive mechanism.

P-GLYCOPROTEIN substrate: moderate interaction

In vitro research has shown that milk thistle can inhibit P-glycoprotein activity, which could increase the absorption of its substrates and thus enhance the effect of the drug. Please use milk thistle with caution if you are taking P-glycoprotein substrates.

Raloxifene: moderate interaction

Laboratory research suggests that milk thistle constituents, silibinin and silymarin, inhibit the glucuronidation of raloxifene in the intestines. Theoretically, this could decrease clearance and increase raloxifene levels.

Rapamycin: moderate interaction

Pharmacokinetic research shows that a silymarin extract from milk thistle decreases the apparent clearance of rapamycin (sirolimus) in kidney transplant recipients with liver failure.

Tamoxifen: moderate interaction

Animal research suggests that silibinin could increase the plasma concentrations of tamoxifen and alter its conversion to an active metabolite. It is unknown whether this interaction occurs in humans. Use milk thistle with caution if you are taking tamoxifen.

Cytochrome P450 substrates: minor interaction

Silibinin is an inhibitor of certain cytochrome P450 substrates. Please use milk thistle with caution if you are taking cytochrome P450 substrates.


Precautions

Hormone-sensitive condition: avoid

Silymarin, a constituent of milk thistle, can bind to the beta-estrogen receptor. Thus, it could have estrogenic effects. Women with hormone-sensitive conditions should avoid using milk thistle. This includes women who have had breast, uterine, ovarian cancer, or endometriosis or uterine fibroids.

Type 2 diabetes: use with caution

Constituents of milk thistle may lower blood glucose levels in patients with type 2 diabetes. Diabetic patients using milk thistle products should be cautious and closely monitor blood glucose levels. Dosage adjustments of antidiabetic medications may be necessary.

Pregnant woman: avoid

Avoid use due to insufficient reliable information available.

Breastfeeding woman: avoid

Avoid use due to insufficient reliable information available. Although milk thistle is used for its galactagogue properties, WHO does not recommend its consumption for breastfeeding women.

Biliary tract obstruction: avoid

Milk thistle promotes bile flow by increasing its solubility, so it is not recommended in cases of biliary tract obstruction.