Milk thistle, which is a flowering plant used as an herbal remedy, is available as a tincture, in tea bags, as a liquid extract, in capsules or as silymarin-phosphatidylcholine complex. The plant has been used by herbalists to treat kidney, liver, gall bladder and other ailments. Scientific studies of milk thistle's therapeutic effects, however, have produced mixed results, as noted by the University of Maryland Medical Center.
Sylibum marianum, or milk thistle, is known by a variety of names, including Scotch thistle, St. Mary's thistle, cardus marianus and blessed milk thistle. The plant, which can reach heights of up to 10 feet, now grows worldwide, but it was originally native to the Mediterranean area. The flower heads are purple and the plant's shiny leaves are a pale green color. Milk-white veins can be seen on the leaves and account for the plant's common name. In some regions, milk thistle is considered a weed because of its ability to grow and spread quickly.
Studies suggest that substances found in milk thistle, such as silymarin, which is a flavonoid with both anti-inflammatory and antioxidant properties, can help protect and strengthen the liver. A study conducted in 2007 demonstrated that silymarin and other substances in milk thistle were antagonistic toward in vitro cancer cells, but further research is needed to prove that they can be effective against cancer within the human body.
The milk thistle herbal remedy products are made from the plant's seeds and typically contain 70 percent to 80 percent concentrations of silymarin. These products have the potential to mimic the hormone estrogen, and should not be taken by women with endometriosis, fibroids or breast, ovarian or uterine cancers, as advised by WebMD.