Milk thistle has long been a popular food in Europe and elsewhere. The young leaves are often eaten in a salad, the young stalks can be steamed like asparagus and the blossom head can be boiled like an artichoke. Milk thistle extract also has a long standing history as a liver tonic. It is even used in German hospitals when poisoning by toxic mushrooms is suspected.

More recently scientists have begin looking at milk thistle for other uses, including its potential as a cancer inhibiting compound (See our Dec. 07 Article on this topic.) More recently research published in the June 11 issue of Journal of Agricultural and Food Chemistry has found that milk thistle may protect the heart and arteries by preventing the oxidation of LDL cholesterol. Oxidation of LDL (bad) cholesterol is believed to be a significant part of the development of atherosclerosis and cardiovascular disease.

In this in vitro, or "test tube" study, the researchers tested both whole extract of milk thistle, called silymarin, and the individual flavonolignans that make up silymarin: silichristin, silidianin, silibinin, and isosilibinin. (An "in vitro" study is not to be confused with an "in vivo" or "in living model" one.) The study consisted of combining LDL cholesterol with varying doses of milk thistle extracts or milk thistle flavonolignans with an oxidant compound, copper sulfate (CuSO₄). The milk thistle extract was tested at 38, 75, 150, and 300 micromoles and had corresponding dose-dependent results. The LDL cholesterol oxidation was reduced by 18%, 73%, 82%, and 86%, respectively. The four major flavonolignans, silichristin, silidianin, silibinin, and isosilibinin, where individually tested at the 300 micromole level. Each of the individual flavonolignans reduced oxidation of the LDL cholesterol, however their combined effect (as the milk thistle extract) was greater at the same level. Silichristin and silibinin each reduced the oxidation of the LDL by 60%, whole silidianin reduced the oxidation by 28.1% and isosilibinin reduced oxidation by 30.1%.

The researchers stated that "these results showed that silymarin and [silibinin], likely through antioxidant and free radical scavenging mechanisms of action, inhibit the generation of oxidized LDL." Indeed, previous research has found milk thistle extract to be a powerful antioxidant. The next question is if an in vivo study can produce the same kind of results.

Learn more about milk thistle here.

1. Wallace, S., K. Vaughn, et al. (2008). "Milk Thistle Extracts Inhibit the Oxidation of Low-Density Lipoprotein (LDL) and Subsequent Scavenger Receptor-Dependent Monocyte Adhesion." J Agric Food Chem 56(11): 3966-3972.