Milk thistle: benefits, dosage & side-effects

23/11/20221 min read

Lilac flowers of milk thistle and thorns. top view

Milk thistle is a plant that grows in the wild and has been used as a herbal remedy for 2000 years. Here's more on the plant including benefits and dosage.

Summary

1What is milk thistle and what does it do?

Milk thistle – also known as Silybum marianum – is a bright pink flowering plant that grows wild in southern Europe, northern Africa and the Middle...

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2Benefits of milk thistle

In the 1960s, scientists extracted silymarin, a trio of active ingredients in milk thistle. It can protect the liver and help it to regenerate...

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3How much milk thistle is safe to take?

The European Medicines Agency recommends taking 300mg-600mg of milk thistle, two or three times a day. People who should avoid taking milk thistle...

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Nutrition

Find out all about milk thistle, including what it does, the benefits to taking it and how much you might need

Written by Carole Beck on December 6, 2018 Reviewed by Azmina Govindji on December 10, 2018

What is milk thistle and what does it do?

Milk thistle – also known as Silybum marianum – is a bright pink flowering plant that grows wild in southern Europe, northern Africa and the Middle East. Traditionally, it’s been used for more than 2000 years to support the liver and spleen.¹

Nowadays, milk thistle is used as a herbal remedy to soothe indigestion and for its liver-protective effects.² It is available as capsules, tablets or a tea.

Benefits of milk thistle

What does milk thistle do in the body?

In the 1960s, scientists extracted silymarin, a trio of active ingredients in milk thistle.³ Silymarin can protect the liver and help it to regenerate, while acting as a natural detoxifier for the liver too, according to a 2014 study published in World Journal of Hepatology.⁴

More research is needed to find out how exactly silymarin works inside the body, but a 2002 study published in Clinical Drug Investigation found it can:⁵

scavenge damaging free radicals
protect cell membranes, for example preventing toxins from entering liver cells
help regenerate damaged cells
neutralise toxins that can damage the liver, such as alcohol

Silymarin also helps reduce inflammation in cells and activates their repair, according to a 2015 study by University of Washington.⁶ However, other studies on milk thistle and its liver-protective effects have been mixed.⁷ If you’re interested in taking milk thistle, talk to your GP or a healthcare professional first.

Milk Thistle (Silybum marianum, cardus marianus, Marian, Saint Mary's, Mediterranean or Scotch thistle)blooming flowers on bright blue sky background

Dosage

How much milk thistle is safe to take?

The European Medicines Agency recommends taking 300mg-600mg of milk thistle, two or three times a day.⁸

These people should avoid taking milk thistle extract:^9,10

pregnant or breastfeeding women – there is no data on its safety people with diabetes – it may reduce blood glucose levels in
people with this disease, putting you at risk of low blood sugar
women with breast cancer, uterine cancer, ovarian cancer, uterine fibroids or endometriosis – it’s thought milk thistle may have oestrogenic effects
people who are allergic to plants in the asteracea family e.g. ragweed, chrysanthemum and artichoke – there is a risk of an allergic reaction