Milk thistle (Silybum marianum) is a traditional European herb, now sold in capsules, teas and gummies. Labels can be hard to compare because they mix extract weights, percentages and “equivalent” claims. This guide explains each one and what amounts are typical.
Key facts
- Silymarin is the active group of compounds in milk thistle extract.
- Silymarin per serving = extract amount × silymarin percentage.
- No official dose exists; the EU herbal monograph lists about 200–1,000 mg of dry extract a day, depending on the extract.
- “Equivalent” amounts describe raw seed, not what is in the gummy.
What is silymarin?
Silymarin is the mix of compounds extracted from milk thistle seeds, which botanists call the fruit. It contains at least seven flavonolignans and one flavonoid, and it makes up about 65–80% of a typical milk thistle extract. Silibinin, sometimes listed separately, is one part of silymarin, not another name for it.
Researchers have called for precise naming because studies use different preparations (Kroll 2007). Silibinin itself is a 1:1 mix of two compounds, silybin A and silybin B. When a label says “silybin” or “silibinin,” it is describing a narrower fraction than silymarin.
What does “standardized to 80% silymarin” mean?
It means 80% of the extract's weight is silymarin, as measured by the manufacturer. To find the silymarin dose, multiply the extract amount by the percentage: 30 mg of an 80% extract gives 24 mg of silymarin, and 250 mg gives 200 mg. In the U.S., “standardized” has no legal definition.
The NIH Office of Dietary Supplements explains that standardization means measuring chemical “markers” to keep batches consistent, and that products labeled standardized are not necessarily more effective, safe or higher in quality. The percentage is still useful: without it you can't calculate silymarin at all.
| Label says | Silymarin per serving | How to read it |
|---|---|---|
| Milk thistle extract 30 mg (80% silymarin) | 24 mg | 30 × 0.80 |
| Milk thistle extract 175 mg (80% silymarin) | 140 mg | 175 × 0.80 |
| Milk thistle extract 250 mg (80% silymarin) | 200 mg | 250 × 0.80 |
| Milk thistle seed powder 500 mg | Not stated | Unstandardized; silymarin can't be calculated |
| Milk thistle 3,000 mg equivalent | Not stated | Raw-seed equivalent; look for extract mg and % |
| Silibinin 100 mg | Not the same measure | Silibinin is one part of silymarin |
How much milk thistle do people typically take?
There's no official dose. NCCIH gives none and says there isn't enough high-quality evidence for firm conclusions. The European Medicines Agency's herbal monograph, based on traditional use, lists dry-extract doses from about 200 mg to about 1,000 mg a day, depending on the extract, taken in two to four doses before meals.
Examples from the EMA monograph: one extract at 82–239 mg two to three times a day (up to 478 mg daily), another at 70 mg three times a day, and another at 200 mg once a day. The monograph covers adults only and does not recommend use under 18.
Clinical research has sometimes gone far higher. A 2012 NIH-funded trial in JAMA gave 420 mg or 700 mg of silymarin three times a day for 24 weeks, doses its authors described as higher than customary, and found no difference from placebo on its main outcome. Trials like this enrolled people with diagnosed medical conditions, so they don't show what milk thistle does in healthy adults (NCCIH).
How much milk thistle is in a gummy?
Check the extract amount and the silymarin percentage per serving, then multiply. Amounts vary widely between brands. Be careful with “equivalent” claims such as “3,000 mg equivalent”: they describe the weight of raw seed used to make the extract, not the amount of extract or silymarin in each gummy.
Extracts are concentrated. The EU monograph describes them by drug-to-extract ratio; 30–40:1 means 30 to 40 g of fruit made 1 g of extract. A small amount of extract can therefore be labeled as a large “equivalent.” The extract amount and silymarin percentage are the figures that let you compare products.
Is it safe to take milk thistle every day?
NCCIH says milk thistle appears to be well tolerated when taken by mouth. The most common side effects are digestive, such as bloating, nausea and gas. People allergic to ragweed, chrysanthemum, marigold or daisy may react to it. Little is known about its safety during pregnancy or breastfeeding.
NCCIH also notes small studies suggesting milk thistle may affect blood sugar in people with type 2 diabetes, so talk with a healthcare provider first if you manage your blood sugar or take any medicine. The EU monograph lists allergy to plants in the daisy family (Asteraceae) as a reason not to use it.
What else should you check on a milk thistle gummy label?
Confirm the plant part (seed or fruit extract), the extract amount, the silymarin percentage, the serving size and the sugar content. If the gummy is a multi-ingredient formula, check that each ingredient has its own amount rather than one blend total. A third-party testing seal confirms contents, not effectiveness.
The NIH Office of Dietary Supplements lists USP, NSF and ConsumerLab.com as independent testers and notes that a seal does not guarantee a product is safe or effective. Under FDA labeling rules, the Supplement Facts panel must show the serving size and the amount of each dietary ingredient per serving.
Zerean Flow: product facts
Zerean Flow is a sugar-free, golden-peach-flavored gummy. Serving size: 2 gummies. 60 gummies per bottle (30 servings).
| Per 2-gummy serving | Amount |
|---|---|
| Dandelion root extract | 150 mg |
| Cordyceps extract (7% cordycepic acid) | 150 mg |
| Artichoke leaf extract | 100 mg |
| N-acetyl cysteine (NAC) | 50 mg |
| Choline bitartrate | 50 mg |
| Milk thistle extract (80% silymarin) | 30 mg |
| Reishi extract (30% polysaccharides) | 30 mg |
| Zinc (as zinc citrate) | 15 mg |
| TUDCA | 10 mg |
Milk thistle in Flow: 30 mg of extract standardized to 80% silymarin gives 24 mg of silymarin per serving. That is less milk thistle than the extract doses in the EU herbal monograph; Flow combines it with eight other ingredients rather than delivering a single high dose. Dandelion root, artichoke leaf, Reishi and Cordyceps are traditionally used botanicals, and research on them in combination is limited. Zinc at 15 mg is within the 40 mg adult upper limit, which counts all sources (NIH ODS).
Price (US, checked October 23, 2026): Subscribe & Save $44.99 for one bottle, $83.98 for two, $119.97 for three. One-time purchase $64.99 for one bottle, $121.32 for two, $173.31 for three. Subscriptions can be paused or canceled anytime. Prices can change; the product page shows the current price.
See Zerean Flow and its full label →
Ingredient amounts from the product label and product page, checked October 23, 2026. Always check the Supplement Facts panel on your bottle.
Sources
- Kroll DJ et al. Milk thistle nomenclature: why it matters in cancer research and pharmacokinetic studies. Integr Cancer Ther. 2007
- NIH Office of Dietary Supplements: Botanical Dietary Supplements — Background Information
- European Medicines Agency: EU herbal monograph on Silybum marianum (L.) Gaertn., fructus (EMA/HMPC/294187/2013)
- Fried MW et al. Effect of silymarin (milk thistle) … a randomized controlled trial. JAMA. 2012
- NCCIH: Milk Thistle
- NIH Office of Dietary Supplements: Dietary Supplements — What You Need to Know
- FDA: Dietary Supplement Labeling Guide, Chapter IV. Nutrition Labeling
- NIH Office of Dietary Supplements: Zinc fact sheet
This article is general information, not medical advice. Talk with a healthcare provider before starting a supplement, especially if you take medicines, are pregnant or breastfeeding, or have a health condition.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.