Milk thistle: silymarin, forms and how to read the label

Milk thistle is a herb grown for its seed, and it's the best-known name on the liver shelf of the supplement aisle. This guide explains what milk thistle is, what silymarin means on a label, the forms it comes in, and the other ingredients you'll meet beside it: dandelion root, artichoke leaf, schisandra and NAC.

It's a label guide, written so you can stand in front of a dozen bottles and know what you're comparing. We describe ingredients, forms and amounts. For how much to take and how often, follow the label on the product you choose.

What is milk thistle?

Milk thistle (Silybum marianum) is a tall thistle with spiny, glossy leaves streaked with white and purple flower heads. It's native to southern Europe and the Mediterranean and now grows wild across much of North America. The white veins on the leaves gave it its common name, and the herb has been part of European herbal tradition for centuries.

Milk thistle belongs to the daisy family, and several related plants turn up on the same shelf: globe artichoke, dandelion, burdock and blessed thistle are all relatives. Young milk thistle leaves and stems were once cooked and eaten as a vegetable, but today it's best known as a herb for dietary supplements.

The part used in supplements is the seed, which botanists call the fruit. The seed holds a group of related plant compounds called silymarin, and that group is what milk thistle supplements are built around. The leaves and flowers aren't what you'll find in a bottle.

With milk thistle, the number that matters is the silymarin, not the size of the capsule.

Silymarin: how to read a milk thistle label

Milk thistle labels give two kinds of numbers, and it helps to know which is which.

1. Find the extract amount. This is the weight of milk thistle seed extract in one capsule or serving, such as 250 mg.
2. Find the silymarin figure. Standardized extracts state how much silymarin they contain, either as a percentage (80% silymarin is common) or in milligrams. 250 mg at 80% works out to about 200 mg of silymarin.
3. Check the ratio for liquids. Tinctures and liquid extracts give a ratio, such as 1:3 or 5–13:1, which tells you how concentrated the extract is rather than a silymarin figure.
4. Read the full serving. Some labels give amounts per capsule and suggest one to three a day; compare products by what one full serving delivers.
5. Look at the other ingredients. Many "liver" formulas pair milk thistle with dandelion, artichoke, turmeric or NAC, so the milk thistle amount per capsule may be lower than in a single-herb product.

Licensed natural health products in Canada also carry an eight-digit NPN and a short statement of use. On milk thistle you'll usually see wording like "traditionally used in herbal medicine to help support liver function". "Traditionally used" means the statement rests on the herb's long history in herbal medicine.

Milk thistle dietary supplements: capsules, liquids and tea

Milk thistle capsules

Capsules are what most people pick up first. Naka, an Ontario supplement maker since 1991, makes Organic Milk Thistle with 250 mg of certified organic seed standardized to 80% silymarin, in a gelatin-free capsule. St. Francis Herb Farm, which has made certified organic herbal products in the Ottawa Valley since 1988, water-extracts its organic seed to 80 mg of silymarin per 500 mg vegicap, with nothing else added. Natural Factors, a British Columbia company with its own organic farms, gives 150 mg of silymarin per capsule with a little dandelion and turmeric, in a gelatin capsule.

Natural FactorsHerbalFactors Milk Thistle250 mg extract, 150 mg silymarin, with dandelion and turmeric. Gelatin capsule.Shop →

Milk thistle liquids and tinctures

If capsules aren't for you, there are three good liquids. Hubner, made in Ehrenkirchen, Germany since 1936, gives 870 mg of milk thistle fruit per 15 mL spoonful with sea buckthorn berry pulp; it's alcohol-free and vegan, and goes in the fridge once opened. Salus, a German family company, makes a fruity liquid with 300 mg of concentrated milk thistle extract per 10 mL, in a base of artichoke leaf, nettle, dandelion, lemon balm and ginger with mango, passion fruit and carrot juices. St. Francis also makes a single-herb tincture, a 1:3 seed extract in organic alcohol and distilled water.

Harmonic Arts, a family herbal company on Vancouver Island, builds Liver TLC around milk thistle seed with dandelion root, burdock root, turmeric, Oregon grape root, astragalus and artichoke leaf. It's a bitter tincture taken in warm water before meals, the way digestive bitters are. Our herbal tinctures guide explains ratios like 1:3 in more detail.

Milk thistle tea

Celebration Herbals bags organic ground milk thistle seed as a tea, and a sprig of peppermint is a nice addition. A tea is a gentle cup rather than a measured supplement, so you won't find a silymarin figure on the box.

Liver support formulas: milk thistle with other supplements

Blends combine milk thistle with other herbs, nutrients and supplements in one capsule, so you get a combination of ingredients rather than one. Here's what you'll see on their ingredient lists.

Other blends on the shelf include Naka Milk Thistle 200 mg, which adds schisandra, dandelion, beet root, barberry and artichoke leaf; Living Alchemy Milk Thistle Alive, organic seed fermented with the company's living culture in British Columbia, with dandelion and turmeric; and the Wild Rose Liver Support Kit, a 15-day programme of three formulas with milk thistle, dandelion, barberry and vitamin C, plus a meal plan.

Dandelion root, artichoke leaf and the other liver herbs

Dandelion root is the herb most often paired with milk thistle. It's one of the classic bitter herbs of Western herbalism, and it comes as capsules, tinctures, pressed juice and roasted root tea. St. Francis Dandelion capsules give whole dandelion plant, root and leaf, as an alcohol-free 5:1 concentrate; Nature's Way Dandelion Root is plain 525 mg root capsules. Traditional Medicinals, an independent tea company since 1974, makes a caffeine-free organic roasted dandelion root tea with a toasty, slightly sweet taste.

You'll see a few other names on liver formulas:

• Artichoke leaf (Cynara scolymus): a bitter leaf, not the artichoke heart we eat.
• Schisandra: a red berry used in traditional Chinese medicine, also sold as a single herb.
• Burdock root: a deep-rooted bitter herb, often in tinctures and blends.
• Turmeric: the golden root, usually listed as curcuminoids or turmeric root. Our turmeric guide covers its forms.
• Chanca piedra: a small tropical plant, Phyllanthus amarus.
• Alpha-lipoic acid and calcium D-glucarate: nutrients that turn up in practitioner blends.

NAC: N-acetyl cysteine

NAC, short for N-acetyl-L-cysteine, is a form of the amino acid cysteine. The body uses cysteine to make glutathione, one of its own antioxidants. You'll find it as a single ingredient and inside liver blends like AOR Liver Support and NFH Liver SAP.

Single NAC products differ mostly in amount per capsule and in what's added. Naka Nutri NAC is NAC on its own in vegetarian capsules; Naka Ultra NAC gives 1000 mg per tablet; CanPrev NAC+ adds L-glycine and selenium; and Designs For Health gives 900 mg per vegetable capsule. NAC also comes up in our CoQ10 and antioxidants guide.

NakaNutri NACN-acetyl-L-cysteine on its own. 150 vegetarian capsules.Shop →

How people take milk thistle

There's plenty of research on milk thistle and silymarin, and this guide doesn't try to summarize it; we stick to what's on the label. There's no single routine either: follow the label on the product you choose. A few practical points help.

• Capsule labels give a number of capsules per day, sometimes as a range. Spreading them across meals is common where the label allows it.
• Liquids come with a measuring cap or spoon; shake the bottle first, as herbal liquids settle.
• Tinctures go in a little water. Liver TLC and other bitter blends are taken before meals.
• Herbs are usually taken steadily for a few weeks rather than once in a while. Some labels suggest at least three weeks.
• Every bottle lists its own directions and cautions, so read the whole label before you start.

Questions we get a lot

What is milk thistle used for?

Milk thistle is one of the best-known herbs in Western herbal medicine. The statement of use you'll see on Canadian milk thistle labels is "traditionally used in herbal medicine to help support liver function". People choose it as a single herb or as the lead ingredient in a liver formula.

What does 80% silymarin mean?

It means the seed extract has been standardized so that 80% of its weight is silymarin, the group of compounds milk thistle is known for. A 250 mg capsule at 80% gives about 200 mg of silymarin.

Is milk thistle the same as blessed thistle?

No. Milk thistle is Silybum marianum, used for its seed. Blessed thistle is Cnicus benedictus, a different plant used for its leaves and flowers. Both sit on the herb shelf, so check the Latin name on the label.

Can I take milk thistle as a liquid instead of capsules?

Yes. Hubner and Salus make liquid milk thistle measured by the spoonful, and St. Francis makes a tincture taken by the dropper. Hubner is alcohol-free; the tincture is made with alcohol and water.

Is milk thistle tea as strong as capsules?

They're different things. A capsule gives a measured amount of standardized extract with a silymarin figure on the label. A tea is ground seed steeped in hot water, a gentle everyday cup without a stated silymarin amount.

What is NAC?

NAC is N-acetyl-L-cysteine, a form of the amino acid cysteine. The body uses cysteine to make glutathione, one of its own antioxidants. It comes as a single supplement and as an ingredient in some liver blends.

Shop milk thistle in Bedford, Dartmouth or online

You'll find milk thistle, dandelion and NAC in the supplement aisle at both stores: 486 Starboard Drive in Bedford and 590 Portland Street in Dartmouth, open seven days. In HRM, order by 11 am with Luminate Express for same-day delivery, or choose pickup. Everything in this guide is shelf-stable, so it ships across Atlantic Canada in 1 to 3 business days, and orders over $80 ship free anywhere in Canada.

Sources: product labels and listings for the items shown. This article is general information, not medical advice.