Named Bioactive Compounds · Compound
Silymarin
Strong Evidenceflavonolignan
Hermetica Superfood Encyclopedia
Silymarin is a flavonolignan complex from milk thistle containing silybin, silydianin, and silychristin that protects liver cells through antioxidant and anti-inflammatory mechanisms. Clinical studies demonstrate its effectiveness in reducing liver enzymes and improving outcomes in nonalcoholic fatty liver disease and cirrhosis.
Silymarin is a standardized extract derived from the seeds of Silybum marianum (milk thistle), a plant native to the Mediterranean region. The extraction process typically yields a mixture of flavonolignans, with standardized extracts commonly containing 70-80% of the active flavonoid compounds.
Multiple randomized controlled trials have evaluated silymarin's efficacy, including a meta-analysis of 8 RCTs (n=587) for NAFLD, a Phase II trial (NCT00680407) testing 420-700mg doses in NASH, and a landmark survival study in 170 cirrhosis patients. Two separate RCTs in breast cancer patients demonstrated protection against chemotherapy-induced hepatotoxicity, while a trial in hepatitis C patients found no antiviral benefit despite good safety.
Clinically studied dosages vary by condition: NAFLD/NASH: 420-700mg daily in divided doses for 48-50 weeks; Chemotherapy protection: 140mg three times daily; Rheumatoid arthritis: 300mg daily for 8 weeks. Standardized extracts typically contain 70-80% flavonolignans. Consult a healthcare provider before starting any new supplement.
Silymarin is a polyphenolic flavonolignan complex extracted primarily from milk thistle (Silybum marianum) seeds, not a food ingredient with conventional macronutrient/micronutrient profile. Bioactive composition: Silymarin complex typically contains 70-80% total flavonolignans by standardized extract weight. Primary components include silybin A and silybin B (silybin/silibinin being the most biologically active, comprising approximately 50-60% of the silymarin complex), isosilybin A and isosilybin B (~5% combined), silychristin (~20% of complex), silydianin (~10% of complex), and taxifolin (a flavonoid precursor, ~3%). Standardized milk thistle seed extracts typically contain 70-80mg silymarin per 100mg extract. Commercial supplements commonly deliver 140-800mg silymarin per daily dose. Macronutrients: Negligible in supplemental form; as a seed-derived compound, raw milk thistle seeds contain approximately 25% protein, 20-25% fixed oils (primarily linoleic acid), and 30-40% carbohydrates, but these are absent in purified silymarin extracts. Bioavailability: Poor oral bioavailability is a key limitation — conventional silymarin has approximately 23-47% absorption with extensive first-pass metabolism. Aqueous solubility is low (~0.04 mg/mL). Phosphatidylcholine complexes (siliphos/silybin-phosphatidylcholine) improve bioavailability by 4-10 fold. Nanoparticle and liposomal formulations further enhance absorption. Peak plasma concentration (Cmax) reached at approximately 1-4 hours post-ingestion. Half-life approximately 6 hours. Primarily excreted via bile (80%) with enterohepatic recirculation noted. No significant vitamin, mineral, or fiber content in purified silymarin extracts.
Silymarin's primary component silybin stabilizes hepatocyte membranes and inhibits lipid peroxidation through free radical scavenging. It modulates nuclear factor kappa B (NF-κB) signaling to reduce inflammatory cytokine production and activates antioxidant enzymes including glutathione peroxidase. The compound also inhibits stellate cell activation, reducing collagen synthesis and liver fibrosis progression.
A meta-analysis of 587 patients with nonalcoholic fatty liver disease showed silymarin significantly reduced AST and ALT liver enzymes compared to placebo. In NASH patients, 22.4% showed liver fibrosis improvement versus 6.0% with placebo in randomized controlled trials. Long-term cirrhosis studies demonstrate improved 4-year survival rates of 58% versus 39% with placebo. Most studies used doses between 140-420mg daily of standardized silymarin extract.
Silymarin is generally well-tolerated with mild gastrointestinal side effects reported in less than 5% of users, including nausea and diarrhea. It may enhance the effects of certain medications metabolized by CYP2C9 and CYP3A4 enzymes, potentially affecting warfarin and some statins. Limited data suggests safety during pregnancy, but consultation with healthcare providers is recommended. Allergic reactions are rare but possible in individuals sensitive to plants in the Asteraceae family.
