Eat your vegetables, they say, but a new study might make you want to rub them on your skin instead. The paper shows that an ingredient extracted from broccoli can help prevent sunburn damage. The researchers hope that the findings will eventually lead to a new type of sun protection that perks up the body's own defenses.
Ultraviolet (UV) radiation and many chemical compounds cause oxidative damage to our DNA, which can lead to cancer. Humans have a natural defense system to break down these oxidizing agents, but UV radiation doesn't kick it into high gear. That's why cancer researchers have been looking for ways to activate these natural antioxidants.
Broccoli and related vegetables produce a compound called sulforaphane that is known to do just that. In previous tests on mice, sulforaphane reduced the inflammation caused by UV radiation. In the new study, pharmacologist Paul Talalay and his colleagues at Johns Hopkins University in Baltimore, Maryland, put the compound to the test in six human volunteers, who each served as his or her own control. Different sections of their backs were exposed to different doses of UV radiation; broccoli sprout extract was applied to some but not to others. The team then determined skin redness--a measure of cell damage--at various intervals after the exposure.
When the extract was applied daily during the 3 days before UV exposure, cell damage, on average, declined by 37%, the team reports online 23 October in the Proceedings of the National Academy of Sciences. An ointment or cream based on sulforaphane could reduce the risk of skin cancer from UV radiation, Talalay says; it would not replace traditional sunscreen--which blocks UV rays--but would help cells handle any damage.
"There is a rising tide of skin cancer occurring all over the world," says dermatologist Francisco Tausk of the University of Rochester Medical Center in New York. "This research may play a big role in turning that tide."
The research could also help organ transplant patients who take immunosuppressive drugs that increase their risk of skin cancer, says pharmacologist Michael Sporn of Dartmouth Medical School in Hanover, New Hampshire. "Chemotherapy is now commonly used to treat cancers, but chemoprevention has met with a lot of skepticism,” Sporn says. "This study clearly shows that it works in humans and should be pursued."