Silymarin

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.