Clinical trials have shown that consumption of grapes can increase the resilience of skin to UV irradiation in about 30-50% of the subject population. New studies published in the current issue of the journal ACS Nutrition Science suggest the effect of consuming grapes on human skin health is much broader – most likely affecting everyone.
The investigation was performed with human volunteers who consumed the equivalent of three servings of whole grapes each day for two weeks. Gene expression in skin was determined before and after grape consumption, with and without exposure of skin to low doses of UV irradiation.
The results demonstrated inter- and intraindividual differences of gene expression in the skin. In other words, from the outset, gene expression in the skin of each individual was different. The expression changed when the subjects consumed grapes or when exposed to UV irradiation, but still each individual was different from one another. Further unique changes were observed when UV irradiation was combined with grape consumption.
Consequently, while gene expression is different when comparing one person to another person, the gene expression of every person changed after consuming grapes.
When searching for a functional commonality resulting from these changes in gene expression after consuming grapes, the investigators were able to construe the myriads of data as being indicative of enhanced skin keratinization and cornification, which are known to create a barrier against environmental damage. This idea was reinforced by exposing skin to a low dose of UV irradiation and measuring the generation of malondialdehyde, a marker of oxidative stress, which was reduced when the subjects consumed grapes.
"We are now certain that grapes act as a superfood and mediate a nutrigenomic response in humans," said John Pezzuto, Ph.D., Professor and Dean of the College of Pharmacy and Health Sciences at Western New England University. "We observed this with the largest organ of the body, the skin. The changes in gene expression indicated improvements in skin health. But beyond skin, it is nearly certain that grape consumption affects gene expression in other somatic tissues of the body, such as liver, muscle, kidney and even brain. This helps us to understand how consumption of a whole food, in this case grapes, affects our overall health. It's very exciting to be working in the post-genomics era where we can finally start to employ functional genomics and actually visualize complex matrices indicative of nutrigenomic responses."
The studies were performed by investigators at Western New England University, Springfield, MA, in collaboration with investigators at Oregon State University, Corvallis, OR. Financial support for the work was provided by the California Table Grape Commission.
Asim Dave, Sumi Piya, Dana-Lynn T. Koomoa, Ingo Lange, Jaewoo Choi, Richard B. van Breemen, and John M. Pezzuto. Inter- and Intraindividual Variation of Gene Expression in Human Skin Following Grape Consumption and/or Exposure to Ultraviolet Irradiation. ACS Nutrition Science, 10.1021/acsnutrsci.6c00003.
