Milk Thistle Extract Dosage Guide: Silymarin per Day, Grades and Bioavailable Forms

Quick-Reference Dosage Table

Evidence	Silymarin dose	Form	Duration
Randomised trials pooled in the 2025 Cochrane review (metabolic dysfunction-associated steatotic liver disease)	Mostly 420 mg/day as 140 mg three times daily; range about 210 to 600 mg/day	Silymarin monotherapy or silymarin complexes	8 to 24 weeks, some longer
Meta-analysis of randomised trials on insulin resistance markers	Similar band	Silymarin	8 weeks and longer
Network meta-analyses of interventions for fatty liver	420 mg/day typical	Silymarin among other agents	24 weeks

The Cochrane review found silymarin generally well tolerated and reported effects on liver enzymes, while grading the certainty of evidence as low and asking for larger trials. For a formulator the operational conclusion is that 420 mg of silymarin per day, in divided doses with meals, is the studied standard, and that the marketing claims available in most markets are limited to structure and function language.

Grade Arithmetic

Trade extracts are standardised to 80% silymarin by UV spectrophotometry (the pharmacopoeial method, expressed as silibinin), and some to lower percentages by HPLC. A 175 mg serving of an 80% extract delivers 140 mg silymarin; three such capsules reach the 420 mg trial dose. Where the COA reports silymarin by HPLC, the figure is usually lower for the same powder because HPLC counts the individual flavonolignans rather than the whole UV-absorbing fraction; the dose should be matched to the method the specification names.

Bioavailable Forms

Silymarin is poorly soluble and its absorption is limited. Phospholipid complexes (phytosomes), solid dispersions and silibinin-specific forms are dosed at lower nominal silymarin figures because they deliver more of the active into the blood. Trials on those forms use their own doses and should be relied on for their own products; a low-dose phytosome and a 420 mg standard extract are not interchangeable in either direction.

Directions and Onset

Trials measured outcomes at eight weeks and later. Directions should state divided daily doses with meals over at least eight weeks. Adverse events in the pooled data were mild, mainly gastrointestinal; allergic reactions are possible in people sensitive to the daisy family.

Formulation Notes

• Capsules and tablets. The 80% extract is a yellow-brown powder that tablets well with a small proportion of binder; 175 mg fits a size 1 capsule with room for excipient.
• Softgels. Suspending the extract in oil improves palatability and may modestly aid absorption; check that the assay is done on the finished fill.
• Specification. Seed-only material, silymarin with method, residual solvent for the extraction solvent used, and a pesticide screen appropriate to a field-grown seed crop.