Milk Thistle Seed Benefits

Milk thistle is a plant whose name comes from the prominent white splashes on its spiky leaves, and its milky sap. Milk thistle seeds have been used medicinally as a ‘liver tonic’ for over two thousand years. According to the Roman naturalist, Pliny the Elder, milk thistle seeds were ‘excellent for carrying off bile’ and it seems he was right!

Milk thistle seeds contain a unique and powerful mixture of at least eight antioxidant flavonoids, which are together known as silymarin. Milk thistle seeds can supply as much as 6 per cent silymarin by weight, and medicinal extracts can be standardised to provide a concentration of 70% to 80% silymarin.

As an antioxidant, silymarin is at least 200 times more potent than vitamin C or vitamin E.

What does milk thistle seed do?

Milk thistle seed extracts are mainly used to support and protect the liver. They are popular among people who drink alcohol regularly, and during detox. I certainly take them before and after a celebration.

Silymarin travels straight to the liver, where it stimulates the production and activity of liver detox enzymes.

Milk thistle is often taken together with globe artichoke which has complementary actions in boosting liver cell metabolism, increasing bile production and reducing fatty liver changes.

In the UK, milk thistle is licensed as a traditional herbal medicine to help relieve the symptoms of over-indulgence and indigestion, to help treat an upset stomach.

Milk thistle and the liver

Cell culture studies suggest the main targets for silymarin are the liver’s own antioxidant enzymes. MIlk thistle seed extracts increase liver concentrations of glutathione, superoxide dismutase and boost the activity of peroxidase enzymes.

Milk thistle also affects transporters and receptors on liver cell membranes, so poisons do not penetrate as easily. By strengthening and stabilizing liver cell membranes, silymarin  and allows liver cells to process toxins at a steady pace, as they enter, rather than being overwhelmed.

Silymarin can protect liver cells from the poisonous effects of excess alcohol, paracetamol and other toxins such as those produced by death cap mushroom and chemotherapy.

Early studies found that, when silymarin is given within 10 minutes of Amanita deathcap poisoning, it can completely counteract the toxic effects, and when given within 24 hours it can reduce liver damage and increase the chance of survival.

Silymarin also stimulates protein production in liver cells to promote their regeneration and reduce the formation of scar tissue (fibrosis) which is one of the hallmarks of liver cirrhosis.

Data from 19 clinical trials found that silymarin had a protective effect in people with liver cirrhosis. Survival rates were significantly higher in those taking milk thistle extracts, both overall and when taking liver-related mortality into account.

The results from 18 clinical trials involving 1088 people with hepatitis due to alcohol, hepatitis B virus or hepatitis C virus, found that liver-related mortality was reduced by 50% in those taking milk thistle in all trials, and by 43% when only high-quality trials were assessed.

Liver function starts to show an improvement within 5 days and continues over at least the next 3 weeks.

Milk thistle reduces inflammation

Silymarin has several anti-inflammatory actions. It reduces levels of an enzyme (COX-2) which is involved in

triggering pain and inflammation. It also inhibits the production of inflammatory leukotrienes and prostaglandins and reduces the migration of inflammatory white blood cells.

This may explain why milk thistle extracts have proven helpful in reducing the inflammation and excessive skin cell turnover that occurs with psoriasis.

It also has an anti-histamine action from stabilising mast cell membranes and reducing their release of histamine.

Milk thistle and diabetes

Milk thistle seed extracts can improve glucose control in people with type 2 diabetes. Studies suggest silymarin reduces fasting blood glucose levels by 15% and improves glycosylated haemoglobin levels, total cholesterol, LDL-cholesterol and triglyceride levels.

Researchers recently found that milk thistle extracts work in a similar way to drugs (thiazolidinediones) prescribed to improve insulin sensitivity in people with type 2 diabetes. If you have diabetes, always talk to your doctor before taking any herbal medicines, to check for any potential drug interactions, and to ensure your glucose levels are closely monitored.

Milk thistle and endometriosis

Silymarin may help the liver metabolise oestrogen more efficiently to reduce symptoms endometriosis.


Milk thistle and chemotherapy

Milk thistle is sometimes advised to protect the liver during or after chemotherapy. Only take under supervision of your oncologist. Red reishi is also interesting for supporting cancer treatment and improving chemotherapy response. If you have cancer, you should ony ever take herbal medicines or other supplements under the advice and supervision of your own doctors.

Milk thistle tea benefits

Silymarin is not water-soluble, and milk thistle tea does not appear to provide effective results for the liver, but is used to help improve digestion and upset stomach.

Milk thistle seed extracts are best taken in tablet or capsule form for optimum results.

Best milk thistle supplements

Milk thistle dose

Select a milk thistle seed product that offers a standardised amount of silymarin (eg 70% to 80%).

Usual doses range from 70mg – 300 mg three times a day.

Start taking them before a party to help protect the liver from the effects of alcohol, and continue to take them for a few days after, too.

Milk thistle side effects

In clinical trials, milk thistle was considered both safe and well tolerated.

A mild laxative effect has been reported at high doses (above 1500mg per day) due to increased bile production. Occasional, mild allergic reactions have occurred.

Image credits: snowbelle/shutterstock; carloredebruin/pixabay; dinesh_valke/ wikimedia;

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