Buying milk thistle: mg of silymarin and price per month
Futures Nutrition Editorial Team · 14 August 2026
Buying milk thistle: mg of silymarin and price per month
Two packs side by side: one says "1,000 mg milk thistle", the other "100 mg silymarin". The first number is ten times larger, the second stands for four to five times as much of the substance that actually matters. Anyone comparing milk thistle preparations therefore needs exactly two figures: milligrams of silymarin per daily portion and price per month. Everything else — number of capsules, the gram figure on the front, the pack price — is misleading.
This page shows how to work both figures out from a label, where comparability ends anyway, and which details a supplier is obliged to state.
Why the number on the front says so little
The reason is the difference between ground fruit and extract. The European Pharmacopoeia requires milk thistle fruit to contain at least 1.5 % silymarin, calculated as silibinin (Ph. Eur. 01/2014:1860). For the refined and standardised dry extract the range is 30 to 65 % (Ph. Eur. 01/2019:2071). The same word on the pack — milk thistle — therefore covers material whose content differs by a factor of twenty to forty.
The EU monograph of the European Medicines Agency (EMA/HMPC/294187/2013, version of 5 June 2018) gives daily amounts per preparation for traditional herbal medicinal products. Applying the pharmacopoeia contents to those amounts gives the following order of magnitude:
| Preparation | Daily amount per monograph | Silymarin per day (calculated) |
|---|---|---|
| Comminuted fruit as tea | 3–5 g per infusion, 2–3× daily | no meaningful figure |
| Powdered fruit | up to 1,800 mg | from about 27 mg |
| Dry extract (acetone), DER 20–70:1 | up to 478 mg | about 143–311 mg |
| Dry extract (ethanol 96 %), DER 30–40:1 | 200 mg | about 60–130 mg |
For tea the column stays empty because silymarin is practically insoluble in water — what ends up in the cup cannot be stated as a milligram value. Which form delivers what is set out in detail in Milk thistle: tea, tincture, capsule or tablet?.
For buying, one simple rule follows: a gram figure without the word "extract" and without a silymarin declaration is not a comparable value. It says how much plant material is in the capsule, not how much of it counts.
Two milligram figures that are not comparable
Even when both packs state a silymarin amount, the comparison is not automatically clean. Silymarin is a mixture of several flavonolignans, and it is determined in two ways: photometrically via a colour reaction, or by high-performance liquid chromatography (HPLC). The EMA assessment report (EMA/HMPC/294188/2013) lists both values for the same extract:
| Extract | photometric | by HPLC |
|---|---|---|
| DER 35–40:1, acetone | 70 mg | 60 mg |
| DER 36–44:1, ethyl acetate | 140 mg | 108.2 mg |
The photometric value is therefore roughly 17 to 29 % higher, because the colour reaction also captures related substances. The method is not printed on the label — it is not required. In practice this means: a difference of 100 versus 120 mg between two preparations may be a real difference in amount, or merely a difference in the laboratory. Only from about a third of a gap does the matter become unambiguous.
How the extract ratio and the percentage relate to each other, and why a declared content of 80 % does not fit the HPLC arithmetic, is explained in Milk thistle 20:1 or 80 %: what the label means.
Price per month, not per pack
The second calculation is pure arithmetic, but it is rarely done, because the pack does not offer it. It takes three steps:
- Coverage = number of units ÷ daily portion (in units)
- Price per 30 days = pack price ÷ coverage × 30
- Price per 1,000 mg silymarin = price per 30 days ÷ (silymarin per day × 30 ÷ 1,000)
The third step is the decisive one, because it removes pack size and dosage at the same time. An example with three constructed packs whose composition is exactly what one finds on the shelf:
| Pack A | Pack B | Pack C | |
|---|---|---|---|
| Contents | 60 capsules, 500 mg fruit powder | 90 extract capsules, 80 mg silymarin | 120 extract tablets, 100 mg silymarin |
| Daily portion | 3 capsules | 2 capsules | 1 tablet |
| Coverage | 20 days | 45 days | 120 days |
| Silymarin per day | about 22 mg | 160 mg | 100 mg |
| Example price | €12.00 | €20.00 | €25.00 |
| Price per 30 days | €18.00 | €13.33 | €6.25 |
| Price per 1,000 mg silymarin | about €26.70 | €2.78 | €2.08 |
The cheapest pack is the most expensive source — by more than tenfold. That is not down to the price but to the fact that pack A contains ground fruit while B and C contain a concentrate. Between B and C, on the other hand, pack size decides: B delivers more silymarin per day, C more per euro.
Which of the two figures counts depends on what is being compared — with the same daily amount, the price; with different daily amounts, first the question of whether one wants the higher one at all. The monograph names up to 478 mg of acetone extract per day; preparations authorised as medicinal products, at three times 140 mg of silymarin (photometric), are well above what food supplements usually carry.
What has to be on the pack
The German food supplements regulation (Nahrungsergänzungsmittelverordnung, NemV) sets out in § 4 which details are mandatory. Paragraph 2 lists five points: the designation "food supplement", the names of the categories of characterising substances, the recommended daily intake in portions, the warning that this amount must not be exceeded, the note on a balanced diet and the note to store the product out of the reach of young children.
For price comparison, paragraph 3 is the more important one: the amount of substances with a nutritional or physiological effect must be stated in relation to the stated daily intake, as an average value based on the manufacturer's analysis of the product. That is precisely the reference figure without which two packs cannot be compared.
There is no percentage of a reference value for silymarin — nutrient reference values apply only to vitamins and minerals. A missing percentage is therefore not a shortcoming with milk thistle; a missing milligram figure per daily portion is.
Warning signs on the label
- No silymarin amount per daily portion. If it only says "milk thistle extract 500 mg", the one comparable value is missing.
- No plant part. The pharmacopoeia describes the ripe fruit. An HPTLC investigation of 31 British products (Frommenwiler et al., Frontiers in Pharmacology 2022;13:925298) found a conspicuous pattern in 11 of 21 food supplements — in eight of those a chlorophyll band, typical of green plant parts and absent from the fruit.
- Health promises. No health claim is authorised for silymarin; under Regulation (EC) No 1924/2006 none may therefore appear on the pack. Article 12 additionally prohibits claims suggesting that not consuming a food could affect health, claims about the rate or amount of weight loss, and references to recommendations of individual doctors.
- "Diet alone is not enough". § 4 paragraph 4 NemV expressly prohibits this assertion.
Batch variation matters for the arithmetic too: in a Czech-American study (Fenclová et al., Scientific Reports 2019;9:11118) the content of two batches from the same manufacturer differed by up to 277 mg per daily dose. A supplier who states a value without a certificate of analysis is stating a target, not a measurement.
Combination products: what you buy along with it
Milk thistle rarely stands alone in the tub. Combinations with artichoke, dandelion, choline or a dietary fibre are common. For the calculation this means: the price per 1,000 mg of silymarin rises, because part of the price is accounted for by the other ingredients. Whether that is worth it depends on the amount of the second ingredient — if it is well below the amount at which anything is documented at all, you are paying for a name on the front.
Inulin is one example: the authorised claim for chicory inulin is tied to 12 g per day, while a preparation often contains 100 mg. That is not a defect, but it does mean the second ingredient is a flavour of the recipe rather than a second active amount — and the price per 1,000 mg of silymarin is what stays comparable.
Our own preparation, worked through
Our tub contains a milk thistle seed extract 20:1 with 80 % silymarin, giving 100 mg of silymarin per tablet, plus 100 mg of inulin from chicory root. Recommended intake: one tablet daily after a meal; when and for how long is covered in Taking milk thistle: timing, duration, fat.
So the pack works out like this: 120 tablets ÷ 1 tablet daily = 120 days of coverage, that is four months; per 30 days, a quarter of the pack price and 3,000 mg of silymarin. Solvent and measurement method are not stated — the content of 80 % is above the pharmacopoeia range of 30 to 65 % and therefore fits a photometric determination, which has to be taken into account when comparing with an HPLC value. Further preparations in the same context are in the liver category.
Food supplements are not a substitute for a balanced and varied diet and a healthy lifestyle.
Frequently asked questions
Is more silymarin automatically better? No. The daily amounts in the EMA monograph are a framework for traditional medicinal products, not a recommendation for food supplements, and there is no authorised health claim for silymarin. The milligram figure is useful for comparing two products — not as evidence that the higher number is the better product.
Why do some packs state only the amount of extract? Because the manufacturer declares the extract as the characterising substance rather than the silymarin. That is permissible; the statement only becomes comparable once the extract ratio and content stand next to it. If both are missing, no silymarin amount can be derived from "500 mg extract".
Is the larger pack worth it? Arithmetically almost always, provided the coverage fits the best-before date. At one tablet a day a 120-tablet tub lasts four months — that is uncritical. At three capsules a day the same number of units is empty after six weeks, and the price per month triples compared with the pack calculation.
Is milk thistle tea the cheaper option? Per gram yes; per milligram of silymarin the question cannot be answered: the flavonolignans are practically insoluble in water, which is why tea packs do not state a silymarin amount. As a comparison figure, tea drops out.
Sources: European Medicines Agency, European Union herbal monograph on Silybum marianum (L.) Gaertn., fructus, EMA/HMPC/294187/2013 (5 June 2018), section 4.2 · Assessment report EMA/HMPC/294188/2013, section 2.1.1 (market data, silymarin photometric and by HPLC) · European Pharmacopoeia, monographs 01/2014:1860 (milk thistle fruit, at least 1.5 % silymarin) and 01/2019:2071 (dry extract, 30–65 %) · German Regulation on Food Supplements (NemV) § 4 · Regulation (EC) No 1924/2006, Articles 10 and 12 · Frommenwiler DA et al., Front Pharmacol 2022;13:925298 · Fenclová M et al., Sci Rep 2019;9:11118.
