Silymarin, a compound found in milk thistle (Silybum marianum) that is used to protect the liver, may help prevent skin cancer caused by sunlight, or ultraviolet radiation.
A recent study from the dermatology department at Case Western Reserve University in Cleveland shows that silymarin reduces the number of skin tumors mice develop after exposure to ultraviolet radiation, which causes cancer by altering DNA structures and by generating cell-damaging free radicals.
In their study, researchers applied silymarin to the skin of mice before exposure to ultraviolet radiation, then concurrently with radiation exposure twice a week. After thirty weeks, the mice were examined for tumors. In the silymarin group, there was a 40 percent reduction in the total number of tumors compared with a control group that received no silymarin. Each mouse in the test group also experienced a 78 percent reduction in the number of tumors and a 9 percent reduction in the size of the tumors that did develop, compared with those of the control group.
Since silymarin has been shown to have strong antioxidant activity, the study’s researchers speculated that this activity may be involved in preventing the skin tumors. The researchers also say that these results warrant conducting clinical trials of silymarin as a skin cancer defense for humans.
Researchers haven’t determined whether the antioxidant activity can be obtained by taking silymarin internally or by using it topically.
—Cindy L. A. Jones
Katiyar, S. K., et al. “Protective Effects of Silymarin against Photocarcinogenesis in a Mouse Skin Model.” Journal of the National Cancer Institute, 1997, 89:556–565.