Melissa / Lemon balm
Melissa / Lemon balm

Milk Thistle

Milk Thistle

Big milk thistle flower growing in virgin forest

Common Name

Milk Thistle

Scientific Name

Silybum marianum (L.) Gaertn.


Milk thistle is a one or two- years old plant which grows up to 1.5 meters. Milk thistle has been classified in Dipsacaceae family, Carduus genus. New botanical system has classified it in Compositae family. Edge of its leaves is wavy and barbed and leaves have white veins and are shiny green. Its flowers are piped and red violet color. Its fruit (seed) is egg-shaped, light-dark brown with hard shell which is protected by hair-shaped, white and silk objects. Its violet flowers have about 190 seeds which have the most medicinal properties. These seeds contain silymarins, an effective compound in Milk thistle extract. Its stalk has ridge and thistle. The main origin of Milk thistle is Mediterranean region. Milk thistle is native to Europe, Middle East, North Africa and some parts of Mediterranean. However it is found all over the world. Many gardeners consider this plant as a weed due to its high growth rate. Usually, it is cultivated on dry rocky soil of Europe, Australia, Canada, China and North and South America as a medicinal plant. Milk thistle fruit (seed) are harvested shortly before it is ripe; when the fruit ripens, the seeds get out of shell. In France, its young leaves, upper part of buds and stem have popularity as a delicious food.

Health Benefits

1. Regulating Blood Glucose Levels

Oxidative tension is involved in pathogenic factors originated by side effects of diabetes increasingly; factors which may cause damage to pancreas beta cell or lead to metabolic disorder which can induce or exacerbate diabetes. Valuable effect of antioxidant nutrients on glycemic control (an index for measuring the effect of food on blood glucose level) on diabetic patients has been reported in experimental and clinical studies. In 2006, a research was designed to diagnose the effects of Milk thistle seed extract (silymarins) which has antioxidant features on glycemic profile in diabetic patients and its results were published in Phytotherapy Research Magazine. A random clinical trial was performed on 51 patients with diabetes type 2 in 2 groups for 4 months. The first group (25 people) received a 200mg tablet containing silymarins along with current treatment daily. The second group (26 people) had the same treatment, but received placebo tablet instead of silymarins. The patients were visited every month and the amount of C glycosylated hemoglobin (HBA-1), fasting blood glucose level (FBS), insulin, total cholesterol level, LDL and HDL, triglyceride, SGOT and SGPT were measured at the beginning and end of the study. SGOT and SGPT are enzymes that exist in liver and heart cells naturally and in the case of damage to liver or heart are released in blood. According to the results, a significant reduction in glycosylated hemoglobin, fasting blood glucose level (FBS), total cholesterol level, LDL, triglyceride, SGOT and SGPT were observed in patients treated by silymarins compared with the placebo and also the values gained at the beginning of the study. Therefore, in patients with diabetes type 2, treating with silymarins for 4 months had a useful effect on glycemic profile. The results of this study were published in Phytotherapy Research Magazine in 2006.

2. Increasing Breast Milk Production

Breastfeeding has important health benefits for infants and mothers. Recently, it has been suggested that Milk thistle (Milk thistle seed) can be used to stimulate milk production by nursing mom. However, the mechanism of function of this medicinal plant is still unknown. In this research, the effect of standard micronized extract of Milk thistle on prolactin serum levels in female rats was assessed. In a 14 days treatment with this extract (25 to 200 mg/kg, oral) prolactin levels increased in a dose dependent method. Also after 66 days pause in treatment with this extract, prolactin levels were still significantly high; but a declining trend in prolactin amount was observed which was confronted through a 7 days additional treatment period with silymarins extract. Bromocriptine (agonist activator (dopamine D2 receptor)) in dose of (1 t0 10 mg/kg, oral) reduces serum prolactin levels. Bromocriptine in dose of 1mg/kg decreases high levels of serum prolactin originated by silymarins significantly. Therefore, this study showed that the extract of Milk thistle seed increases prolactin levels in blood circulation significantly in female rats. It seems that in some cases this effect is related to dopamine D2 receptors. The results of this study were published in Phytomedicine Magazine in 2009. 

3. Calming Anxiety and Stress 

Obsessive- compulsive disorder (OCD) is a current neurological-psychological disease. Although various medicinal factors exist for treating OCD, but psychologists understood that often many patients can’t bear side effects of these drugs and respond to treatment properly or the drugs lose their effect after a treatment period. Herbal medicine can be a solution for some of these problems. In fact, there are many plants with psychedelic effects and fewer side effects. These plants can be used as an alternative treatment and/ or in order to increase effectiveness against common symptoms of OCD. The purpose of this study is to compare the effect of Milk thistle extract with Fluoxetine (an anti-depression drug) in OCD treatment. This study is an 8 weeks, preliminary, double-blinded and random trial. According to an organized clinical interview, 35 adults who had indicators of suffering from OCD participated in this trial. In this random study, patients randomly received a 600mg capsule of Milk thistle extract or a 30 mg capsule of Fluoxetine for 8 weeks. The results didn’t show any significant difference between the extract and Fluoxetine in OCD treatment. Also there wasn’t any significant difference between the two groups regarding the observed side effects. The results of this study were published in Progress in Neuro-Psychopharmacology and Biological Psychiatry Magazine in 2010.

4. Anti-Inflammatory

The extract containing silymarins active ingredient and Milk thistle seed have anti-inflammation and anti-arthritis effects that is due to strong antioxidant features and trapping free radicals (as pre-inflammation factor). Silymarinss is more effective in cases that arthritis is relapsing in comparison to cases that arthritis has developed. Silymarins and Silybinins prevent inflammatory process through inhibiting neutrophil migration and inhibition of kupffer cells.

5. Anti-Allergy

Silymarins and silybinins in Milk thistle inhibit formation of inflammatory mediators (prostaglandins and leukotriene) and release of histamine from basophils. Therefore, Milk thistle seed may have anti-allergic and anti-asthma activities.

6. Increasing Antioxidant Activity

According to reports, silymarins as a very effective antioxidant causes imprisoning of free radicals (active oxygen species) and inhibition of lipid peroxidation; so protects cells from oxidative tension which leads to an increase in enzymatic and non-enzymatic antioxidant immune system of the cells including decreased glutathione, superoxide dismutase and catalase. This system can protect liver, brain, heart and other organs due to its ability in preventing lipid peroxidation and replacement of decreased levels of glutathione. Silybinins has protective membrane features and this feature can protect blood components of oxidative damage.

Antioxidant effect of silymarins in preventing liver damage resulted from Psychotropic drug (treatment of psychopathy) was assessed. This trial was done on 60 patients who were under chronic treatment by psychotropic drug that received silymarins or placebo for 90 days. The results showed that silymarins consumption reduces lipoperoxidative liver damage. According to the results of this study, lipoperoxidative increase may be related to liver damage originated by Psychotropic drug. The results of this study were published in Current Therapeutic Research magazine.

7. Improving Liver Function

History of consumption of Milk thistle seeds for liver care dates back to first century. Antioxidant activity is one of the most important factors in liver protection. According to available evidences, Milk thistle may protect liver through a series of mechanisms such as antioxidant activity, blocking toxic compounds in cell membrane, increasing protein synthesis, antifibrotic activity and anti-inflammation or moderating effects of the immune system.

– Anti-hepatotoxicity potential: Silymarinssprotects liver against so many toxic factors of liver in human and animals. Some mushrooms such as amanita phalloides (amanita, known as death warrant) and A. Virosa contain two toxins of phalloidin and alpha-amanitin; these two toxins cause destruction of hepatocytes cell membrane and blocking liver protein synthesis that leads to severe liver damage and death. Silymarins prevents these effects effectively through two ways of 1- blocking the toxin junction, 2- increasing capacity of regeneration of liver cells. Intravenous injection of silybinins during 24 hours after mushroom consumption is an effective action against liver damage. In a study 60 patients with severe poisoning with amanita mushroom were treated by herbal tea containing 20mg/kg silybinins; the best results were achieved and no death was observed. Silymarins is often used as supportive treatment in food poisoning originated by mushroom consumption. Milk thistle protects liver against ischemic damage (reduction of blood flow in organs), extra amounts of iron and x-ray glow.

– E committee of Germany confirms silymarins consumption for treating liver diseases such as hepatitis A, cirrhosis of the liver originated by alcohol consumption and hepatitis originated by chemicals.

– Liver cirrhosis originated by alcohol consumption: Ethanol metabolism includes free radicals leading to oxidative tension in liver. Silymarins confronts liver cirrhosis originated by alcohol consumption successfully through antioxidant mechanisms and maintaining liver biochemical factors at normal level.

– Hepatitis: in patients with acute viral hepatitis, silymarins reduced treatment period and improved serum bilirubin and liver enzyme levels. Also the amount of biochemical parameters in patients who were treated with silymarins reached normal levels earlier.

– Liver fibrosis: Liver fibrosis can lead to a change in liver structure which leads to hepatic failures. Silymarins controls this process significantly that indicates its anti-fibrosis potential.

– Restoration of liver tissue: Silymarins stimulates restoration of liver tissue through increasing protein synthesis in damaged liver. In trials performed on liver of the rats, silybinin increased formation of ribosomes, DNA synthesis and protein synthesis. The interesting thing is that increase of protein synthesis originated by silybinin was observed just in damaged livers and this effect was not observed in healthy liver samples.

8. Boosting Immune System

Activity of adjusting body immune system associated with silymarins in patients with liver diseases may include liver protective function in this compound. Silymarins protected rats against suppressed immune system originated by UV radiation in vitro. Silybinin controlled T lymphocytes and human multi-core leukocyte. Full-time consumption of silymarins improves immune system through increasing T lymphocytes (one of the types of immune system cells), intercoolins (blood white cells compounds which adjust immune system response) and decreasing all types of immunoglobulin (every type of protein in serum and every type of immune system cell that acts as antibody.

Silymarins can be useful as a supportive drug in cases which require suppression of immune system such as autoimmune diseases and types of infections.

9. Anti-Microbial

Although silymarins does not affect virus proliferation, but has a helpful effect on hepatitis virus, through its controlling function on inflammatory and cytotoxic (cell toxicity) processes originated by viral infections. Silybinins controls growth of cells infected with hepatitis B virus through inducing cell death. Also, silymarins has controlling activity against other virus in different cell lines.

10. Regulating Blood Cholesterol Levels

Silymarins consumption by patients with high blood fat (type 2) causes mild reduction of total cholesterol levels and HDL cholesterol level in blood plasma. Silymarins reduced cholesterol plasma levels and LD lipoprotein in rats with high blood fat, while silybinins did not reduce cholesterol plasma levels in normal rats; although, reduced total phospholipid levels. Also cholesterol level and biliary phospholipid concentration in rats was reduced gradually.  Part of reduction in cholesterol level and biliary phospholipids originated by silymarins consumption in both human and rat samples may be due to reduction in liver cholesterol synthesis. Silymarins can be a new factor in preventing and treating high blood fat and atherosclerosis.

11. Anti-cancer

In 2014 a study with the purpose of diagnosing anti-cancer effects of silymarins on two cell lines of breast cancer, BT-474 and SK-BR-3 was performed and its results were published in Advances in Breast Cancer Research magazine. SK-BR-3 and BT-474 cell lines were provided from cell bank of Pasture center. Cells were cultured in standard conditions (37degrees Celsius, 95% humidity and 5% carbon dioxide pressure).  Sk-BR-3 and BT-474, two cell lines of breast cancer were incubated for 24 hours and then 100, 200, 400, 800 and 1600 micromole silymarins was added to the culture environment of every cell lines. Milk thistle controlled growth of two cell lines of breast cancer of BT-474 and SK-BR-3 in different densities after 24, 48 and 72 hours. Silymarins increased cell death in both cell lines. Silymarins can be combined with other chemotherapy drugs in order to achieve better results.

12. Improving Cardiovascular System Function

During cancer treatment period, consumption of some chemotherapy drugs is limited due to toxic effect on heart; this effect is created by oxidative tension and apoptosis induction (cell death). Silybinins has cardiovascular protective features due to antioxidant and membrane protection functions. In 2017, a research with the purpose of diagnosing protective features of oil fractions of Milk thistle seed extract against destructive effect of gamma ray in female Albino rats was done and its result was published in Int J Pharm Pharm Sci magazine. Malondialdehyde (MDA), reduced glutathione (GSH), metalotathione (MT) in heart and brain tissues of rats was estimated. Also lactate dehydrogenizes (LDH) and creatinine kinase MB in serums of rats and biomarkers of brain including dopamine and serotonin were measured. Treatment of destructive effect of gamma ray with consumption of Milk thistle seed extract and its oil fractions lead to a significant reduction in malodialdehyde levels in heart and brain tissues.  However significant increase of decreased glutathione levels was observed in heart and brain tissues. Also significant increase in dopamine and metalothionin levels of heart tissue was observed. According to the results it can be concluded that Milk thistle seed extract and its oil fractions have a protective effect against heart and brain damage originated by gamma ray.

13. Improving Nervous System Function

Silymarins has been useful in prevention and treatment of neurodegenerative (nerve wrecking) and neurotoxic (toxic effect on nerves) processes due to its antioxidant effects. Silymarins can protect dopaminergic neurons against nerve toxicity originated by lipopolysaccharide in brain effectively. Silymarins in dose of 200 (mg/ kg/ daily) reduced protein oxidation in hippocampus and cortex of old rats compared with young rats. Silymarins can be used as an optional compound against Alzheimer in which protein oxidation is an important preliminary incident. According to previous studies, silymarins has antioxidant activities in central nervous system which enters central nervous system through brain-blood barrier.

14. Improving Kidney Function

Silymarins helps in maintaining normal kidney function. Silymarins effect in rats with diabetes mellitus induced by alloxan was examined. Alloxan produces active oxygen species which damage kidney tissue. Silymarins was consumed for 20 days after 9 weeks treatment with alloxan which was effective in kidney tissue damages. This compound has antioxidant effect through increasing expression of antioxidant gene-enzymes and increasing some of most important protective mechanisms against damages of free radicals containing superoxide dismutase, glutathione peroxidase and catalase. Therefore, silymarins can be used as a drug for treating diabetic nephropathy.

15. Increasing Fertility

In 2015 a research with the purpose of investigating the effect of silymarins on reproduction variables in male Wistar rats with liver fibrosis originated by carbon tetrachloride was done and its results was published in The American Journal Innovative Research and Applied Sciences. The results of the study showed that liver fibrosis originated by carbon tetrachloride reduces some reproduction variables in male rats. This effect happens because of hypogonadism (producing small and a few amount of hormone by gonads) originated by reduction of spermatogenic function in testis, steroidogenic function and reduction in plasma level of gonadotropin of pituitary (FSH and LH). Significant reduction has been observed in change of cell arrangement in testicles area in the group that has been treated by silymarins.

16. Increasing Bile Secretion

Liver protective effect of silymarins on bile secretion regarding secretion of bile salts in Wistar rats was studied. Silymarins in doses of 25, 50, 100 and 150 (mg/kg/daily) for 5 days caused a dose dependent increase in bile flow and secretion of bile salts. The most effect was observed in dose of 100 (mg/kg/daily). According to the results, silymarins increases bile secretion.

Bioactive Compounds

The active constituents of milk thistle seed are three flavonolignans namely silibinin, silychristin, and silidianin collectively called Silymarin. Silibinin is the most biologically active. It also contains betaine, apigenin, silybonol, fixed oil (linoleic acid, oleic acid, palmitic acid), protein, tocopherol, sterols (cholesterol, campesterol, stigmasterol, sitosterol), free fatty acids and mucilage.

Traditional Use

– Milk thistle had been used as a medicine since 4th century B. C.  History of Milk thistle consumption in liver diseases dates back to 1700s and its consumption for liver treatment can be understood from Greek resources.

– Nicholas Kalper- English botanist in 17th century- in his writings had mentioned that Milk thistle is useful in treating jaundice and obstruction of the liver and spleen.

– Eclectic therapeutic system (therapeutic system according to selection of the best therapeutic method among other methods) in 19th and 20th century had used Milk thistle in treating varicose veins, menstrual pains and congestion of liver, spleen and kidney.

– In homeopathy medicine, a tincture (aqueous-ethanol essence with 25:75 proportions) of Milk thistle seeds had been used in treating liver disorders, jaundice, bile stone, and peritoneum inflammation, bleeding, types of bronchitis and varicose veins.

– In 16th century, a short time after wars, Milk thistle had been used to help depression and emotional distress. Europeans continued Milk thistle consumption with the same purpose.

– In early 18th century, people had used Milk thistle in treating other disease such as irregular menstrual, varicose veins, kidney and spleen problems. Also today Milk thistle is used as an effective therapeutic method in treating these diseases.

– Dioscorides–physician of Roman army- had used Milk thistle in treating snakebite. Milk thistle seed had been used by Saxons as a method in treating infective diseases originated by bite of rabid animals which today is known as hydrophobia, (water phobia is considered as a symptom of rabies).

– Milk thistle seeds contain an active ingredient which has a particular effect on liver. Rademache, German physician in 19th century- prescribed a tincture of its seeds for his patients. Due to its successful effect, today this tincture exists in pharmacopoeia list named as Tinctura Cardui Mariae Rademacher.

– In Chinese traditional medicine, Milk thistle is used in heat removal and disposal of body poisons.

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