New York, Eating grapes can help protect against sunburn and ultraviolet (UV) skin damage and natural components found in the fruits known as polyphenols are thought to be responsible for these beneficial effects, according to a new study.

The results published in the Journal of the American Academy of Dermatology revealed that participants in the study showed increased resistance to sunburn and a reduction in markers of UV damage at the cellular level.

"Grapes may act as an edible sunscreen, offering an additional layer of protection in addition to topical sunscreen products," said lead researcher Craig Elmets from University of Alabama, Birmingham in the US.

The study investigated the impact of consuming whole grape powder -- equivalent to 2.25 cups of grapes per day -- for 14 days against photodamage from UV light.

The participants' skin response to UV light was measured before and after consuming grapes for two weeks by determining the threshold dose of UV radiation that induced visible reddening after 24 hours -- the Minimal Erythema Dose (MED).

The results showed that grape consumption was protective as more UV exposure was required to cause sunburn following grape consumption, with MED increasing on average by 74.8 per cent.

Analysis of skin biopsies showed that the grape diet was associated with decreased DNA damage, fewer deaths of skin cells, and a reduction in inflammatory markers that if left unchecked, together can impair skin function and can potentially lead to skin cancer.

"We saw a significant photoprotective effect with grape consumption and we were able to identify molecular pathways by which that benefit occurs -- through repair of DNA damage and downregulation of proinflammatory pathways," said Elmets.

Most skin cancer cases are associated with exposure to UV radiation from the Sun -- about 90 per cent of nonmelanoma skin cancers and 86 per cent of melanomas, respectively.

Additionally, an estimated 90 per cent of skin ageing is caused by the sun.