"Don't forget to eat your broccoli."
It is likely that few, if any, of us never heard these words of advice from our parents at one time or another.
Less often heard was that extracts from broccoli, when applied to the skin, may provide health benefits as well.
But new research has found that doing just that may help reduce the redness and inflammation caused by sun damage — and subsequently decrease the risk of skin cancer.
The findings were published Monday in the journal Proceedings of the National Academy of Sciences.
Lead study author Dr. Paul Talalay, in the department of pharmacology and molecular sciences at the Johns Hopkins School of Medicine, emphasizes that the chemical component from broccoli sprout extract is not a sunscreen. Unlike sunscreen, the extract does not absorb UV light and "does not prevent the radiation from penetrating into the skin," he says.
What it does, he says, is "boost the protective systems of the cell to counteract the damage caused by ultraviolet radiation.
"Treatment with broccoli sprout extract might be another protective measure that alleviates the skin damage caused by UV radiation and, thereby, decreases our long-term risk of developing cancer," Talalay says.
Such a finding could be more relevant as the incidence of skin cancer continues to rise, possibly due to increased exposure to ultraviolet light and the decay of the ozone layer.
Fifteen years ago, Talalay first identified a chemical — sulforaphane — which he isolated from cruciferous vegetables, including broccoli. He found that this protective chemical prevented tumor development in a number of animals, even when they were exposed to cancer-causing agents.
In this current study of mice and six human volunteers, he applied broccoli sprout extract to small areas of the volunteers' skin. Each volunteer then received doses of ultraviolet radiation — either on the same area where the broccoli extract had been applied or on an untreated region of skin.
What Talalay found was that the redness and inflammation caused by the damaging effects of UV radiation were reduced by 37 percent in skin areas treated with broccoli extract.
He says that it takes many hours, and even days, for these protective measures to take effect. However, Talalay notes, these results linger, lasting even days after the topical broccoli sprout extract was washed away.
"To our knowledge," says Talalay, "this is the first direct demonstration where we can protect human tissues against a recognized and widely distributed environmental carcinogen — ultraviolet light."
Dr. David Leffell, a professor of dermatology and surgery at the Yale School of Medicine, says the reduction in redness reported in the research is certainly impressive. He adds, though, that he was not surprised to see this result.
"This is consistent with the anti-inflammatory effects documented by others from natural and nutritional compounds," he says. "We would expect to see such an effect because broccoli is strong in antioxidants."
However, Dr. Hensin Tsao, director of the Massachusetts General Hospital Melanoma and Pigmented Lesion Center at the Harvard Medical School, says that broccoli sprout extract needs to be tested on a larger scale due to the limited number of volunteers in this particular study. But Tsao believes the ongoing research on improved sun-protective compounds is valuable.