Big skin-care news: A study has found that UV damage to the skin continues for hours after you’ve left the sun and that melanin—the pigment that gives skin its color—may be contributing to this damage.
The study, conducted by researchers at Yale University and published in the journal Science, is groundbreaking for a few reasons. A breakdown of the most noteworthy findings: “When you go to the beach and sunlight hits your arm, it makes the kind of DNA damage that causes melanoma mutations within a second,” explains Douglas E. Brash, a senior research scientist in therapeutic radiology and dermatology at Yale School of Medicine (and the lead author of the study). “This is so fast that about all you can do is prevent it with sunscreen or a hat, or hope that your body repairs the damage afterward. We discovered that in addition to this instantaneous damage, the cells continue to make DNA damage for hours afterward. What’s really exciting is that this happens through a kind of chemistry seen before in fireflies but not in mammals. UV rays trigger free-radical chemistry that excites an electron in a fragment of melanin to a very high energy. The energy goes into DNA and causes damage.”
It’s been commonly understood that fair-skinned people—those of us with less melanin—are more sensitive to sunlight (and more prone to sunburns and skin cancer), which made sense since melanin has long been known to block harmful UV light. But if melanin is also responsible for damaging DNA, as the study suggests, does that imply that those with darker skin tones are more prone to sun damage? Not exactly. “The melanin does indeed block UV light, as we always thought. But it is also doing something harmful. This is evidently the best compromise that evolution could come up with; on balance it is better than doing nothing. Second, yellow melanin, which is present in those with blonde or red hair, is worse at blocking UV light and better at making delayed DNA damage. So the trade-off is poorer for yellow melanin,” says Brash.
But it’s not all bad news. In fact, these new findings suggest that it’s possible to fight sun damage after exposure—meaning if you accidentally overdid it at the beach or missed a spot with your sunscreen, you’re not completely helpless. It might be possible to prevent sun damage even after sun exposure through the use of post-sun sunscreens. “Because there’s continued DNA damage in the evening, the study suggests that perhaps antioxidants should be used at night,” says Joshua Zeichner, the director of cosmetic and clinical research at Mount Sinai Hospital in New York City. “Traditionally we recommend antioxidants in the morning and daytime to prevent damage, but perhaps given this data we should be incorporating them in the evening as well.” Zeichner recommends looking for antioxidant ingredients, like vitamin C, ferulic acid, vitamin E, resveratrol, and phloretin, which help combat free-radical damage and could therefore theoretically help with this type of post-sun-exposure damage. (A few of our favorite antioxidant-rich picks: SkinCeuticals Phloretin CF and DermaDoctor Kakadu C 20% Vitamin C Serum with Ferulic Acid & Vitamin E.)
For more on protecting skin from the sun, watch: