New research shows that a suncream made from broccoli juice can help to organise the body's defences against damaging ultraviolet (UV) rays.
The extract was found to reduce sunburn symptoms by up to 78% when it was tested on six volunteers who were exposed to pulses of UV radiation.
Researchers also found that traditional sunscreens used in the same experiments are essentially ineffective.
The ointment, which is made from extracts of three-day-old broccoli sprouts which are rich in compounds called sulphoraphanes, does not absorb UV light to prevent it entering the skin.
Instead, it works inside the body by boosting the production of enzymes that protect cells against UV damage and the risk of skin cancer.
The effects are said to be long lasting, providing protection that lasts for several days, even when all traces of the extract are gone.
Lead author Professor Paul Talalay said: "Treatment with this 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."
The results are reported in the journal Proceedings of the National Academy of Sciences.