The two-part study, funded by the California Table Grapes Commission, was published in the Journal of the American Academy of Dermatology and revealed that the subjects displayed increased resistance to sunburn and a reduction in markers of UV damage at the cellular level.
Study details
The research was conducted at the University of Alabama, Birmingham and led by principal investigator Craig Elmets, MD. Elmets et al 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 study involved 19 healthy human volunteers aged 19 and older, with Fitzpatrick skin types I-III.
The subjects' skin response to UV light was measured before and after consuming grapes for two weeks. This was determined by the threshold dose of UV radiation that may produce sunburn after 24 hours, known as the Minimal Erythema Dose (MED).
Findings
The results, which showed a 74.8% increase in natural protection of the skin, indicate that oral consumption of grapes has systemic beneficial effects in healthy adults, according to the report.
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.
“The increased resistance to sunburn was demonstrated by an increase in the Minimal Erythema Dose (MED) which identifies the lowest dose of UV exposure that causes a sunburn. It was measured before and after two weeks of grape consumption, and the results showed that it required more UV exposure to cause sunburn after consuming grapes for two weeks, indicating that grapes offered protection,” explained Dietitian Courtney Romano, Health Advisor for the California Table Grape Commission. “The study also evaluated what was happening in the skin at the cellular level, because UV radiation can cause changes such as increased inflammation, damage to DNA, and cell death. The researchers found that a grape-enriched diet “turned off” or downregulated genes that are associated with inflammation, DNA damage, cell death, and activated genes involved in suppressing tumors.”
"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. "Grapes may act as an edible sunscreen, offering an additional layer of protection in addition to topical sunscreen products."
But don’t run to the wine aisle just yet.
“Although wine contains beneficial grape compounds, because it is alcohol there isn’t a direct comparison that can be made,” said Romano. “Additionally, there are some studies that have suggested that alcohol increases sun sensitivity.”
According to Skin Cancer Foundation, an estimated 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.
Opportunity
According to Romano, most grape supplements on the market contain isolated grape compounds. This current study is different because it looked at the impact of consuming the whole grape, which has a number of natural compounds.
“This research is exciting because our current findings provide building blocks for additional studies that may eventuate in an oral photoprotective product from a natural source,” said the authors.
Source: Journal of the American Academy of Dermatology
January 20, 2021; doi: 10.1016/j.jaad.2021.01.035
“Dietary table grape protects against UV photodamage in humans: 1. clinical evaluation”
Authors: A. Oak et al.
Source: Journal of the American Academy of Dermatology
January 20, 2021; doi: 10.1016/j.jaad.2021.01.036
“Dietary table grape protects against UV photodamage in humans: 2. molecular biomarker studies”
Authors: A. Oak et al.