Abstract
The fruit of the milk thistle plant (Silybum marianum, family Asteraceae/Compositae) has been a liver support remedy for 2,000 years.1 The standardized extract known as silymarin contains three flavonoids of the flavonol subclass. Silybin predominates, followed by silydianin and silychristin. Silybin is an effective antioxidant, conserving glutathione (GSH) in liver cells while stabilizing the liver cell membranes against oxidative attack.1 Animal experiments have shown silybin blocks the oxidative toxicities of acetaminophen, alcohol, carbon tetrachloride, and the mushroom toxins phalloidin and alpha-amanitin.2-4 These findings correlate with decades of clinical observations that silybin improves survival after ingestion of death cap mushrooms (Amanita species).5 Although silybin is the most potent of the flavonoids in milk thistle, like other flavonoids it is not well-absorbed. The utilization of non-phytosome silybin intravenously in mushroom-toxic patients (at 20-50 mg/kg/day) or of high-dose silymarin at 600 mg/day in diabetic patients has resulted in meaningful symptom improvement,6 presumably because the preparations were given either intravenously or at high oral doses. However, silybin-phosphatidylcholine complex as a phytosome provides significant liver protection and enhanced bioavailability over conventional silymarin.