A recent human study published this week in the scientific journal Antioxidants found that consuming grapes protected against ultraviolet (UV) damage to the skin. Study subjects showed increased resistance to sunburn after consuming 2 ¼ cups of grapes every day for two weeks. Additionally, subjects displaying UV resistance also demonstrated unique microbiomic and metabolomic profiles suggesting a correlation between the gut and skin. Natural components found in grapes known as polyphenols are thought to be responsible for these beneficial effects.
This new study reinforces previous research in this area, according to Dr. John Pezzuto, lead author of the paper and Professor and Dean of the Western New England University College of Pharmacy and Health Sciences in Springfield, MA. https://www.mdpi.com/2076-3921/11/12/2372
In this investigation with 29 human volunteers, researchers examined the impact of consuming whole grape powder – equivalent to 2.25 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. 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 – UV protection remained after reverting back to no grape consumption for 4 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.
Over 3 million Americans are affected by skin cancer each year, largely as a result of exposure to sunlight. It is estimated that 1 in 5 Americans will develop skin cancer by the age of 70. Most skin cancer cases are associated with exposure to UV radiation from the sun: about 90% of nonmelanoma skin cancers and 86% of melanomas, respectively. Additionally, an estimated 90% of skin aging is caused by the sun.
The phrase 'Let thy food be thy medicine and medicine be thy food' dates back to the time of Hippocrates. Now," he adds, "after 2500 years, and as exemplified by this human study conducted with dietary grapes, we are still learning the reality of this statement."
John Pezzuto of Western New England University
Pezzuto, J.M., et al. (2022) Short-Term Grape Consumption Diminishes UV-Induced Skin Erythema. Antioxidants. doi.org/10.3390/antiox11122372.