Best Milk Thistle Supplement 2026: Ranked by Cost per Silymarin
Informational summary — not medical advice. This page ranks product verifiability & cost; on whether milk thistle works, see the evidence.
With milk thistle, "best" means "discloses a silymarin %" — not cheapest. Silymarin is the active, and cost per actual active is computable only when the label prints a percentage. Of the 12 products here, only 5 disclose a silymarin % (typically 80%); the other 5 hide it behind an extract or "4:1"/"full-spectrum" number, so their cost-per-silymarin is incomputable. We rank the disclosers by cost per 100 mg silymarin, and that gap is the whole story.
As an Amazon Associate we earn from qualifying purchases. Ranked by disclosed silymarin, then cost per 100 mg silymarin, never commissions.
The one-line takeaway There is no clean "cost per active silymarin" ranking for the whole field, because it requires a number most products hide: a disclosed silymarin %. Only 5 of 12 disclose one; for the other 5, cost per 100 mg silymarin is literally incomputable. A cheaper, bigger-milligram bottle that hides its % isn't a better buy — you can't verify what active you're getting.
Every product compared: disclosure & cost
Sorted disclosed silymarin % first (by cost per 100 mg silymarin), then the phospholipid form, then undisclosed products by cost per serving — not by the extract milligram number. Read the Silymarin % and Verdict columns, not the extract mg. Cost per 100 mg silymarin is blank where undisclosed, because it can't be computed. Full data is a public CC BY JSON file.
| Product | Form | Extract mg | Silymarin % | Silymarin mg | $ / serving | $ / 100 mg silymarin | Verdict |
|---|---|---|---|---|---|---|---|
| NOW Foods Silymarin Milk Thistle Extract 300 mg, Double Strength (100 Capsules) | capsule | 300 mg | 80% | 240 mg | $0.17 | $0.07 | Discloses silymarin % |
| Jarrow Formulas Milk Thistle 150 mg, 30:1 Standardized (100 Capsules) | capsule | 150 mg | 80% | 120 mg | $0.17 | $0.14 | Discloses silymarin % |
| Solaray Milk Thistle One Daily, Seed Extract 350 mg (60 Capsules) | capsule | 350 mg | 80% | 280 mg | $0.51 | $0.18 | Discloses silymarin % |
| Pure Encapsulations Silymarin 250 mg (120 Capsules) | capsule | 250 mg | 80% | 200 mg | $0.38 | $0.19 | Discloses silymarin % |
| Nature's Way Milk Thistle, 175 mg Seed Extract, 80% Silymarin (120 Capsules) | capsule | 175 mg | 80% | 140 mg | $0.26 | $0.19 | Discloses silymarin % |
| Thorne Milk Thistle Phytosome (Siliphos) (90 Capsules) | capsule | — | undisclosed | — | $0.53 | n/a | Phospholipid form — not raw-mg comparable ⚠ |
| Thorne S.A.T. — Milk Thistle + Artichoke + Turmeric (60 Capsules) | capsule | — | undisclosed | — | $0.78 | n/a | Phospholipid form — not raw-mg comparable ⚠ |
| Swanson Full Spectrum Milk Thistle 500 mg (100 Capsules) | capsule | 500 mg | undisclosed | — | $0.11 | n/a | Silymarin % undisclosed ⚠ |
| Horbaach Milk Thistle 3000 mg, 4:1 Extract (300 Capsules) | capsule | 3000 mg | undisclosed | — | $0.11 | n/a | Silymarin % undisclosed ⚠ |
| Nature's Bounty Milk Thistle 1000 mg, Rapid Release Softgels (50 ct) | softgel | 1000 mg | undisclosed | — | $0.19 | n/a | Silymarin % undisclosed ⚠ |
| Himalaya Milk Thistle Liver Support 350 mg (60 Capsules) | capsule | 350 mg | undisclosed | — | $0.43 | n/a | Silymarin % undisclosed ⚠ |
| Gaia Herbs Milk Thistle Seed, Liquid Phyto-Caps (120 Capsules) | capsule | — | undisclosed | — | $1.28 | n/a | Silymarin % undisclosed ⚠ |
Prices are live Amazon buy-box figures, July 2026; they move. Cost per serving = price ÷ servings per container at the labeled serving. Extract mg is the marketed milk-thistle weight, not silymarin. Silymarin mg = extract mg × disclosed %. Cost per 100 mg silymarin is shown only where a % is disclosed — incomputable otherwise; see the label trap.
Reading the verdicts, honestly
Three outcomes, and only one is a clean, verifiable cost-per-active comparison:
- Discloses silymarin % — prints an extract mg and a silymarin % (here, 80%), so actual active mg and cost per 100 mg silymarin are computable. The only tier you can rank on active cost. 5 of 12 products.
- Phospholipid form — silybin-phosphatidylcholine (Siliphos/phytosome). Built for higher absorption, so its milligrams aren't raw-comparable to a standardized extract; it sits outside the raw-mg ranking. 2 products.
- Silymarin % undisclosed — an extract, "4:1," or "full-spectrum" number with no percentage. Cost per active is incomputable — you can't verify the dose. 5 of 12 products.
Watch for numbers that look like a dose but aren't silymarin: "1,000 mg" softgels, "3,000 mg" 4:1 extracts, and "full-spectrum" claims all describe seed weight or a ratio, not active content. None is USP- or NSF-verified for potency here; Thorne is third-party self-certified and Himalaya's USDA Organic covers identity, not potency — see the label trap.
The phospholipid form sits outside the raw-mg ranking
These are legitimate products — but an absorption-enhanced form can't be lined up against a standardized-percentage extract on cost per 100 mg silymarin, so treating them as interchangeable with an 80% capsule is the mistake:
- Thorne Milk Thistle Phytosome (Siliphos) (90 Capsules) — phospholipid form. Silybin-phosphatidylcholine (Siliphos), marketed for higher silibinin absorption. Not raw-milligram comparable to a standardized extract, so it's excluded from the cost-per-active ranking ($0.53/serving). Third-party certified (Thorne).
- Thorne S.A.T. — Milk Thistle + Artichoke + Turmeric (60 Capsules) — phospholipid form. Silybin-phosphatidylcholine (Siliphos), marketed for higher silibinin absorption. Not raw-milligram comparable to a standardized extract, so it's excluded from the cost-per-active ranking ($0.78/serving). Third-party certified (Thorne).
Frequently asked questions
What is the best milk thistle supplement?
One that discloses a silymarin %. Only 5 of 12 do, so cost per active is computable only for them. On cost per 100 mg silymarin, NOW Foods Silymarin Milk Thistle Extract 300 mg, Double Strength (100 Capsules) leads (~$0.07). Cheapest per serving ≠ best.
Why can't you rank everything by cost per active?
Because that needs the silymarin content, and 5 of 12 products don't disclose it (variation is ~2,800% independent, 35–125% of label peer-reviewed). Cost per 100 mg silymarin is left blank for them. The gap is the finding.
Is the Thorne phospholipid form comparable?
Not on raw mg. Its silybin-phosphatidylcholine (Siliphos) form is built for absorption, not standardized to a %, so it can't be ranked against an 80% extract on cost per 100 mg silymarin. We tag it phospholipid-form and keep it outside that ranking.
Related
- Milk thistle: what it is & who it's for
- The silymarin label trap — why the big milligram number isn't the dose
- Milk thistle dosage guide — the ~420 mg/day silymarin target + a calculator
- Does milk thistle work? — the honest evidence, including the mortality null
Sources
- Manufacturer labels and live Amazon pricing for all listed products, July 2026. Full dataset: /milk-thistle/cost-by-brand.json (CC BY 4.0).
- Fenclová M, et al. "Poor chemical and microbiological quality of commercial milk thistle supplements." Sci Rep. 2019. PMID: 31366891 (silymarin content 35–125% of declared; 4/26 samples <50%).
- ConsumerLab.com. Milk thistle supplements review (independent testing; silymarin per serving varied ~2,800%, 2/6 at 40–60% of label). Not peer-reviewed; full results member-only.
- U.S. Pharmacopeia / German Commission E — milk thistle extract standardized to ~70–80% silymarin (pharmacopeial convention, not a clinical trial).