Folks showed increased resistance to sunburn after consuming 2 ¼ cups of grapes every day for two weeks. 

Consuming grapes can protect against ultraviolet (UV) damage to the skin, according to a new study in Antioxidants.

Folks showed increased resistance to sunburn after consuming 2 ¼ cups of grapes every day for two weeks.  Additionally, subjects displaying UV resistance demonstrated unique microbiomic and metabolomic profiles suggesting a correlation between the gut and skin.  The polyphenols found in grapes are thought to be responsible for these beneficial effects, the study authros conclude.

In the study of 29 people, researchers examined the impact of consuming whole grape powder – equivalent to 2 ¼ cups of grapes per day – for 14 days against photodamage from UV light.  Subjects’ 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).  Additionally, metabolomic analysis of the gut microbiome, blood, and urinary samples was undertaken. 

Ultimately, one-third of the subjects demonstrated UV resistance following grape consumption, and these same subjects displayed significant differences in the microbiome and metabolome compared with the non-responders.  Notably, the same three urinary metabolites were depressed in the UV-resistant group, the study showed  One metabolite in particular (2’-deoxyribose) is a strong indicator of reduced photodamage and suggests unique genetic profiles of relevance for personalized medicine.

Furthermore, three of the UV resistant subjects showed a durable response where UV protection remained after reverting back to no grape consumption for four more weeks.  This work suggests that a segment of the population is capable of resisting sunburn following grape consumption, and that there is a correlation between the gut-skin axis and UV resistance.

"Let thy food be thy medicine and medicine be thy food' dates back to the time of Hippocrates.  Now, after 2500 years, as exemplified by this human study conducted with dietary grapes, we are still learning the reality of this statement,” says  study author John Pezzuto, professor and dean at Western New England University in Springfield, Mass. in a news release.