U.S. researchers have discovered that as well as being healthy food, broccoli also helps skin cells fight off damage caused by harmful ultraviolet radiation.
The researchers say an extract from newly sprouted broccoli seeds reduced skin redness (erythema) and damage by more than one-third compared with untreated skin and the extract has already been shown to help skin cells fight UV damage in mice.
The team from Johns Hopkins University say this is the first time it has been seen that human tissue can be protected directly against a known human carcinogen.
Dr. Paul Talalay who led the study says the extract is not a sunscreen, but instead helps fortify skin cells to fight the effects of UV radiation.
Dr. Talalay says unlike sunscreens, which provide a physical barrier against UV rays by absorbing, blocking or scattering the light, the extract helps boost the production of protective enzymes that defend against UV-related damage.
Dr. Talalay has been studying the compound in broccoli sprout extract, sulforaphane, for more than 15 years and says it has been shown to prevent tumor development in a number of animals treated with cancer-causing agents.
For the study Talalay and his colleagues tried the extract on six people; they tested different doses of the extract on several small patches of skin, which was then exposed to a short pulse of UV radiation sufficient to cause varying degrees of sunburn.
The redness of the skin in the treated and untreated areas was then compared as redness is a measure of a series of processes that go on in the skin which are harmful, including DNA damage.
They found that the highest doses of the extract reduced redness and swelling by an average of 37 percent and the effect was long-lasting.
Talalay says there was still an effect two days after the treatment was stopped.
Genetic differences meant the effect varied widely among the volunteers, ranging from 8 percent to 78 percent protection, but Talalay says the important point is that they have shown it works in humans.
How it should be applied to humans says Talalay requires further research but the extract might be useful as a means of protecting against exposure to UV radiation, especially in people with suppressed immune systems who are most at risk for skin cancer, such as transplant patients.
Talalay says that 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.
According to the National Cancer Institute skin cancer is the most common cancer in the United States, and affects more than 1 million Americans every year and kills more than 10,000 people each year - about 4 percent of all cancer deaths.
The research is published in the current issue of the Proceedings of the National Academy of Sciences.