Your mother may have told you to eat your broccoli, but it turns out that wearing it may be equally beneficial.

A team of Johns Hopkins scientists reports in this week’s issue of the Proceedings of the National Academy of Sciences that humans can be protected against the damaging effects of ultraviolet radiation — the most abundant cause of skin cancer — by wearing a topical solution containing an extract from broccoli sprouts.

A recent study on human volunteers, as well as previous studies on mice, show that the degree of skin redness caused by UV rays, which is a tell-tale sign of inflammation and cell damage, is markedly reduced in extract-treated skin.

The broccoli chemical extract is not a sunscreen, said investigator Dr. Paul Talalay, a professor of pharmacology, in a news release. Unlike sunscreens, this topical solution does not absorb UV light and prevent its entry into the skin.

Instead, it works inside cells by boosting the production of protective enzymes that defend cells against many aspects of UV damage. And, unlike sunscreen, the protection lasts for several days, even after the extract is no longer present on or in the skin.

The protective chemical agent in the broccoli sprout extracts is sulforaphane. It was first identified by Talalay and his colleagues more than 15 years ago and has been shown to prevent tumor development in a number of animals treated with cancer-causing chemicals.

Talalay and his team most recently tested six healthy human volunteers. Each one was exposed to a pulse of UV radiation on small patches of their skin (less than 1 inch in diameter) that were either treated or untreated with different doses of broccoli extract.

At the highest doses, UV-induced redness and inflammation were reduced by an average of 37 percent with the use of the topical solution. The extracts were protective even when applied three days prior to UV exposure.

The protection varied among the subjects, ranging from 8 percent to 78 percent, which Talalay said may be due to genetic differences among individuals, local differences in the skin or other factors such as dietary habits. He added that conventional sunscreens were essentially ineffective in these experiments.