(Agencies)
Updated: 2007-10-26 10:23

What's good for your diet may also guard against skin cancer.

Scientists have discovered that an extract of broccoli sprouts protects the skin against the sun's harmful ultraviolet rays.

That's not the same as calling the extract a sunscreen, however.

"This is not a sunscreen, because it does not absorb the ultraviolet rays of the sun," explained Dr. Paul Talalay, a professor of pharmacology and molecular sciences at Johns Hopkins University School of Medicine in Baltimore. "We don't want people covering their bodies with broccoli and going to the beach. They will have no protection whatsoever."

Exposure to ultraviolet or UV rays is the primary cause of most skin cancers. The incidence of skin cancer in the United States is on the rise as men and women who had too many sunburns earlier in life get older and develop the disease.

Talalay started working on skin cancer prevention about 25 years ago. "Cells contain an elaborate network of protective genes that code for proteins that protect against four principal injurious processes to which all of our cells are exposed and which are the causes of cancer, degenerative disease and aging," he explained.

Those four processes are: oxidation; DNA damage; inflammation and radiation, namely ultraviolet radiation.

The cells' protective system normally operates at about one-third capacity, so the real question is what would ramp up that system.

"Our strategy has been to find things that will boost the system," Talalay explained. Broccoli, in particular, has previously reported to have some anti-cancer effects.

"We looked in vegetables, and it turned out they had a rather large quantities of a compound that induced this system, particularly in cruciferous vegetables such as broccoli, cabbage, Brussels sprouts, et cetera," Talalay said.

The compound, called sulforaphane, is found in broccoli sprout extracts and was first identified by Talalay and his colleagues more than 15 years ago. Sulforaphane has been shown to inhibit tumor development in animals.

For this study, Talalay and his colleagues tested the compound in both mice and humans.

The human experiments involved six healthy volunteers. Each participant was exposed to UV radiation on two circles on their back that were either treated or not treated with different doses of broccoli extract.

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