Milk thistle seed extract standardized to silymarin (and silymarin/silybin marker rows) vs. Silybin-phosphatidylcholine complex (phytosome, e.g. Siliphos)
Among 849 on-market milk thistle (silybum marianum) products with an identifiable primary form, 96.8% use Milk thistle seed extract standardized to silymarin (and silymarin/silybin marker rows) (822 products) and 3.2% use Silybin-phosphatidylcholine complex (phytosome, e.g. Siliphos) (27).
| Milk thistle seed extract standardized to silymarin (and silymarin/silybin marker rows) | Silybin-phosphatidylcholine complex (phytosome, e.g. Siliphos) | |
|---|---|---|
| Quality tier | Tier 2 | Tier 1 |
| Milk Thistle (Silybum marianum) by weight | — | — |
| Share of market | 96.8% | 3.2% |
| On-market products | 822 | 27 |
| Median declared dose | 175 mg middle half: 90–262.5 | — |
| Most common brands | Source Naturals, Life Extension, NOW | Life Extension, Terry Naturally, SuperSmart |
Doses are declared per serving in mg. “By weight” is the share of the ingredient that is the nutrient itself (e.g. elemental magnesium in a magnesium salt).
Why Milk thistle seed extract standardized to silymarin (and silymarin/silybin marker rows) is tier 2
The preparation used in the NASH trials cited on the compound (Legalon, a standardized silymarin preparation), but silybin plasma exposure was lower than that of a silybin-phosphatidylcholine complex in two small human pharmacokinetic comparisons, one of them a crossover (see the phytosome form). Rows whose own name is "Silymarin"/"Silybin" are marker-compound mass, not extract mass, so they are recorded without a dose to avoid double counting with the extract row they are nested under.
Source: Barzaghi N et al. 1990, Eur J Drug Metab Pharmacokinet 15(4):333-338, PMID 2088770; Mendez-Sanchez N et al. 2019, BMC Pharmacol Toxicol 20(1):5, PMID 30635055
Why Silybin-phosphatidylcholine complex (phytosome, e.g. Siliphos) is tier 1
Compared directly against plain silymarin in healthy volunteers: plasma silybin was much higher after the complex in a 9-subject study (single doses, complex vs silymarin equivalent to 360 mg silybin) and in a separate 23-subject crossover (45 mg complex vs 70 mg silymarin tablets, P<0.0001). Small pharmacokinetic studies in healthy volunteers, not outcome trials; the 2019 paper carries two published errata not reviewed here. The complex's declared mass is not comparable with extract mass, so rows named after it are recorded without a dose.
Source: Barzaghi N et al. 1990, Eur J Drug Metab Pharmacokinet 15(4):333-338, PMID 2088770; Mendez-Sanchez N et al. 2019, BMC Pharmacol Toxicol 20(1):5, PMID 30635055