Research studies conducted in the laboratory have investigated the properties of silymarin or its isomer silybin using cell lines and animal models. Other substances in milk thistle have not been extensively studied.
Several research studies have investigated the effects of silymarin or silybin in a noncancer context. These studies have tested silymarin or silybin:
Cannabis, also known as marijuana, is a plant grown in many parts of the world (see Question 1).
The use of Cannabis for medicinal purposes dates back to ancient times (see Question 3).
By federal law, possessing Cannabis is illegal in the United States (see Question 1).
In the United States, Cannabis is a controlled substance that requires special licensing for its use (see Question 1 and Question 3).
Cannabinoids are active chemicals in Cannabis that cause drug -like effects...
Silymarin or silybin has also been investigated in cancer models. The effects of silymarin and/or silybin have been investigated in prostate (DU 145, LNCaP, PC-3),[1,2,3,4,5,6]breast (MDA-MB 468, MCF-7),[7,8,9]hepatic (HepG2),[10,11] epidermoid (A431),colon (Caco-2),ovarian (OVCA 433, A2780),histiocytic lymphoma (U-937), and leukemia (HL-60) [15,16]cells. In animal tumor models, tonguecancer, skin cancer,[18,19,20,21,22,23]bladder cancer, and adenocarcinoma of the colon [25,26] and small intestine  have been investigated. These studies have tested the ability of silymarin or silibinin to:
Mitigate the toxicity associated with chemotherapy agents.
Enhance the efficacy of chemotherapy agents.
Inhibit the growth of cancer cell lines and inhibit tumor initiation or tumor promotion.
Although many of these studies have produced encouraging results, none of the findings have been replicated in human clinical trials.
Laboratory data suggest that silymarin and silybin protect the liver from damage induced by toxic chemicals. Animal studies have found that liver cells treated with silybin and then exposed to toxins do not incur cell damage or death at the same rate as liver cells that are not treated with silybin. This finding suggests that silybin can prevent toxins from entering the cell or effectively exports toxins out of the cell before damage ensues.[11,27,28,29,30,31] Alternatively, this may be related to the effect of silymarin on detoxification systems. In vitro data have shown silybin to stimulate and/or inhibit phase I detoxification pathways in silybin-treated human liver cells. However, this effect was found to be dose-dependent, and these levels are not physiologically attainable with the current manufacturer dose recommendations.[32,33]