Eating grapes daily changes how skin genes behave, helping protect against the aging and damaging effects of the sun. New research found that consuming three servings of grapes each day for two weeks altered gene activity in the skin, with a unique pattern for each individual. One of the clearest effects was a reduction in malondialdehyde, a marker of oxidative stress, after skin was exposed to ultraviolet (UV) light. Lower malondialdehyde levels indicate less cell damage from the sun, demonstrating that grapes provide biological protection even when no visible change in sunburn resistance is observed.
Grapes Enhance Skin Barrier Function
Grapes also boosted genes involved in skin barrier function. Specifically, the fruit enhanced genes related to processes that help the skin form a protective barrier against germs, chemicals, and water loss. This stronger barrier helps the skin better handle environmental threats like UV radiation. Skin damage due to UV exposure is a leading cause of skin cancer, which affects nearly six million Americans annually.
Dr. John Pezzuto, who led the research, stated that the same effect likely occurs in other parts of the body as well, calling grapes a superfood that triggers a nutrigenomic response, meaning food directly influences gene behavior. The researchers believe the process begins in the gut, where grape compounds interact with gut bacteria, sending signals through the gut-skin axis to alter how skin genes work.
Study Details and Findings
To investigate the effects of grapes on the skin, the researchers recruited 29 healthy volunteers for their study, published in ACS Nutrition Science. For two weeks, participants consumed a special freeze-dried grape powder equivalent to three full servings of fresh grapes each day, which is about three cups or 45 to 60 grapes. The scientists took small skin punch biopsies from a sun-protected area on the hip and a spot on the back exposed to a low dose of ultraviolet light. These samples were collected both before and after the two-week grape consumption period.
The team then subjected the skin samples to a series of lab tests, measuring malondialdehyde—a chemical marker of UV-induced oxidative stress—using a special staining technique. They also extracted RNA from skin biopsies to analyze gene expression, comparing which genes were turned on or off after grape consumption. Additionally, blood samples were drawn to analyze changes in hundreds of different fats in the bloodstream.
Even in the four volunteers who showed no visible improvement in sunburn resistance, eating grapes still reduced malondialdehyde after UV exposure. Most notably, each person's genetic activity shifted after eating grapes for two weeks. The changes varied from person to person, but all pointed in a positive direction. Grapes reduced UV skin damage in 26 volunteers.
- In one volunteer, grapes turned on genes that help build a tougher, more resilient outer layer of skin.
- Grapes boosted another volunteer's skin barrier genes through different genetic control switches.
- In another person, grapes activated genes that help skin fight germs and resist oxidative damage.
Impact on Blood Lipids
The researchers also observed widespread changes in the study participants' good blood lipid (fat) levels. Nearly all measured lipids, which are essential structural components of skin cell membranes, increased after daily grape consumption. A rise in these fats helps skin cells remain strong, flexible, and tightly packed together, creating a better seal against moisture loss and a stronger barrier against germs and chemicals. Unsaturated fatty acids mostly increased, while some saturated fats decreased. These lipid shifts are known to support skin barrier function and reduce inflammation.
Dr. Pezzuto commented: "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."
Preventing Skin Cancer
Staving off sun damage could help prevent millions of skin cancer diagnoses each year. Repeated UV exposure damages DNA in skin cells, and over time, this accumulated damage—which appears as pigmented spots on the skin—can trigger uncontrolled cell growth leading to skin cancer. When UV rays hit the skin, they penetrate deep into skin cells and damage their DNA, the genetic instruction manual that tells cells how to grow and behave. Most of the time, the body can repair this damage, but over years of repeated UV exposure, the damage accumulates. Eventually, the DNA becomes so severely damaged that cells begin to grow out of control.
This uncontrolled growth can take several forms. Some skin cancers, including basal cell carcinoma and squamous cell carcinoma, are very common—accounting for more than 90 percent of skin cancers—and are rarely fatal if caught early and removed. However, the most dangerous form is melanoma, which affects roughly 112,000 Americans annually. Melanoma grows in the cells that produce skin pigment and can spread quickly to other organs, including the liver, lungs, and brain. Once melanoma spreads, it becomes harder to treat and more likely to prove fatal. If caught early, about 95 percent of patients survive, but that rate sinks to 35 percent once the cancer has spread. Protecting one's skin helps prevent those initial DNA errors from happening in the first place. Sunscreen, clothing, and shade block or absorb UV rays before they reach skin cells.
