Milk thistle (silymarin)

What is milk thistle?

Milk thistle, botanically Silybum marianum, is a thistle from the Mediterranean with purple flowers and white-veined leaves. Food supplements use its seeds (botanically, fruits). They contain silymarin, a complex of flavonolignans such as silibinin.

No health claims for milk thistle are authorised in the EU. This page is therefore about standardisation, forms and the differences between products.

Extract, seed powder or liquid?

• Standardised extract: usually standardised to 80 % silymarin – the most common form.
• Full spectrum / seed powder: ground seeds without concentration, often with a high milligram figure but little silymarin.
• Liquid extract: as drops, practical if you do not like capsules.
• Combinations: with artichoke, dandelion, turmeric, glutathione, alpha-lipoic acid or NAC.

Our range

• NOW Foods: Milk Thistle Extract with 450 mg (Extra Strength) and 750 mg (Maximum Strength), Double Strength with artichoke and dandelion, a version with turmeric and Glutathione with milk thistle extract and alpha-lipoic acid.
• Swanson: Milk Thistle (Standardized) with 250 mg, Full Spectrum with 500 mg, Milk Thistle Combination and Liquid Extract.
• Osavi: Milk Thistle with 100 mg silymarin, Milk Thistle Dandelion & Artichoke and Glutathione with Silymarin.
• Other brands: Life Extension Silymarin and Advanced Milk Thistle, Jarrow Formulas, Nature's Answer, Zein Pharma, Essensey, Allnutrition, Applied Nutrition, Puritan's Pride and Holland & Barrett.

What to look for

• Silymarin content: in per cent and in mg per serving. This is the key figure for comparison.
• Extract or powder: 500 mg of seed powder provides less silymarin than 250 mg of an 80 % extract.
• Extras: combinations sometimes contain alcohol (in tinctures) or other plants.
• Medicines: if you take medicines or are pregnant, ask your doctor first.

Follow the dose on the label. Food supplements are not a substitute for a varied diet.

Frequently asked questions

What is silymarin?

Silymarin is a mixture of substances from milk thistle made up of several flavonolignans. Extracts are standardised to it.

Why do the mg figures differ so much?

Some products state the amount of extract, others the amount of seed powder or silymarin. Check the nutrition table.

Is there liquid milk thistle?

Yes, for example Swanson Milk Thistle Liquid Extract.