Milk Thistle
Milk thistle in standardised capsules, tablets, liquid extracts and combined formulas. We explain what the silymarin percentage on the label means, which form fits daily use and how to take it with food.Read more →
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Silymarin, extract strengths and labels: reading a milk thistle supplement properly
Milk thistle and silymarin in plain words
Milk thistle (Silybum marianum) is a purple flowering plant from the daisy family, and one of the most asked-for plants in our range of herbal supplements. Products use the small dark seeds. Those seeds contain silymarin, a group of plant compounds with silybin as the main one. Silymarin is the part that gets measured and printed on labels. It also dissolves poorly in water, which is why the way a product is made changes how much you absorb.
The big number on the front of the pack is rarely the dose
UK packs advertise 3,000 mg, 10,000 mg, sometimes 20,000 mg. That figure is almost always an extract equivalent: how much dried seed the extract was made from, often at a 40:1 ratio. What you actually swallow is the extract weight plus its silymarin percentage. A tablet with 100 mg of a 40:1 extract standardised to 80% silymarin gives you 80 mg silymarin, and can still be sold as "4,000 mg milk thistle". Two packs with the same headline number can differ several times over in silymarin. Compare the silymarin per daily dose, or the extract weight and percentage together. If a label states neither, there is nothing to compare.
Forms, and what each one is good for
- Standardised seed extract in capsules or tablets: silymarin stated on the label, so your intake stays the same from batch to batch.
- Whole ground seed: closer to the traditional herb, but silymarin is not standardised and is far lower per gram.
- Liquid extracts and tinctures: handy if you dislike swallowing tablets. Strength varies more between brands, and some contain alcohol.
- Phytosome extracts: the silymarin is bound to lecithin, a fat-like carrier, so more is absorbed from a smaller amount.
- Combinations, often with artichoke extract and choline, for people who want a broader formula instead of a single herb.
How we choose the milk thistle we stock
We judge milk thistle on three things: the form, the silymarin content stated per daily dose, and whether a combination actually adds something. We prefer standardised seed extracts, because you can see what you take and repeat it tomorrow. We still carry whole seed and liquids for people who want them, and we say plainly when a label allows a fair comparison and when it does not. We buy directly from the brands, so what reaches you is authentic. Our compliance team checks every product before it goes live, we test ourselves, and independent labs spot-check batches. Read how we select our brands.
Who it suits, and what to expect
Most milk thistle sold in the UK is a food supplement. The European food safety authority (EFSA) has not authorised a health claim for it, so we make no promises here, and you should be wary of anyone who does. Separately, some milk thistle products are registered herbal medicines with a THR number from the MHRA. Those carry an approved traditional wording for the symptoms of occasional over-indulgence of food and drink, and they state on the pack that they are medicines. Both routes are for adults: THR products are not for under-18s, and not for use in pregnancy or breastfeeding.
It suits adults who want a well-defined seed extract as part of a steady routine, often next to dandelion root products or a bitter herb blend. Take it with a meal containing some fat, since silymarin is absorbed better that way, and judge it after several weeks of consistent use rather than after a weekend.
Frequently asked questions
What is milk thistle and what is silymarin?
Milk thistle (Silybum marianum) is a thistle from the daisy family, native to the Mediterranean and now common across Europe. Supplements are made from its seeds, which botanists call fruits. The seeds contain silymarin, a group of plant compounds known as flavonolignans. Silybin is the largest part of that group. When a label says "standardised to 80% silymarin", it means the extract has been adjusted so each batch delivers a consistent amount of these compounds.
What does "10,000 mg" on a milk thistle label actually mean?
It is almost always an extract equivalent, not the amount in the capsule. Extracts are concentrated, often at 40:1, so 250 mg of extract can be described as 10,000 mg of milk thistle seed. The figures that let you compare products are the extract weight and the silymarin percentage, or better still the milligrams of silymarin per daily dose. A high headline number with no silymarin figure tells you nothing useful.
Which form of milk thistle should I choose?
It depends on how precisely you want to dose and how you like taking supplements.
| Form | What it is | Suits |
|---|---|---|
| Standardised extract | Seed extract, silymarin on label | Consistent daily use |
| Whole ground seed | Not standardised, lower content | Traditional whole-herb approach |
| Liquid or tincture | Drops, strength varies | Trouble with tablets |
| Phytosome | Silymarin bound to lecithin | Smaller dose, better absorption |
| Combination | With artichoke or choline | Broader digestive formula |
For most people a standardised extract is the clearest starting point.
When and how should I take milk thistle?
Take it with a meal that contains some fat, such as eggs, olive oil or nut butter. Silymarin dissolves poorly in water, and dietary fat improves how much of it reaches your bloodstream. Some products are split across two or three servings a day, which is how most research has dosed it. Follow the label of the specific product, since extract strengths differ widely, and keep the timing the same each day so you can judge it fairly.
Can I combine milk thistle with other supplements?
Yes, and many UK formulas already do it. Milk thistle is often paired with artichoke, dandelion root or choline, which is why so-called 3-in-1 products are common. We only stock combinations where the second ingredient is present in a meaningful amount, not as a dusting on the label. If you already take a bitter herb blend or a product from our digestion range, check the labels so you are not doubling up.
How long before I notice anything?
Milk thistle works gradually, not within hours. If you use it as part of a daily routine, give it at least two to three weeks of consistent use before drawing conclusions, and in studies of longer-term markers changes were measured over months rather than days. That is an honest limitation, not a reason to skip it: the value lies in steady use of a well-defined extract, so take it at a dose you can actually keep up.
What is the difference between a milk thistle food supplement and a THR herbal medicine?
Both are sold in the UK, but they sit under different rules. A food supplement may not carry a health claim, because none has been authorised for milk thistle. A THR product has been assessed by the MHRA for quality and safety and may use an approved traditional wording.
| Type | Permitted wording | Age |
|---|---|---|
| Food supplement | No authorised health claim | Adults |
| THR herbal medicine | Traditional use, over-indulgence | 18 and over |
Who should not take milk thistle?
Registered milk thistle medicines in the UK state that they are not for children or teenagers under 18, and not for use during pregnancy or breastfeeding. The same caution is sensible for food supplements. Avoid it if you are allergic to plants in the daisy family (Asteraceae), which includes daisies, marigolds and artichoke, since cross-reactions are possible. If you have an existing liver condition, speak to your GP or pharmacist before starting.
Does milk thistle interact with medication?
It can, and this is where a pharmacist is worth more than a product page. Silymarin is handled by the same liver enzyme systems that process many prescription medicines, so it may in theory change how quickly some drugs are broken down. Reports also mention added effects with blood sugar lowering medication. If you take prescribed medicines, especially for diabetes or anything with a narrow safe range, check with your GP or pharmacist before adding it.
