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It’s well known that ultraviolet rays wreak havoc on skin, causing it to lose its suppleness and uniform tone. But simply slapping on sunscreen in the morning isn’t going to keep your complexion looking its best as the years tick by.

“Yes, photodamage accounts for 90 percent of wrinkles and aging,” says nutrition expert Kathy Napoli, who teaches on this topic (see below) and others at the John Muir Women's Health Center. “But a lot of other factors affect the health of your skin. Itake a holistic approach.”

Stress, for example, doesn’t do your skin any favors, she says. “Too much cortisol—a hormone produced in response to stress—takes a toll on your skin.” So find ways to chill out, whether it’s a long soak in the tub or a vigorous run. Not only is exercise a great stress beater, “it’s also important because it oxygenates the skin. Don’t overdo it, though,” Napoli cautions. Extreme exercise can overoxygenate skin, causing damage.

Perhaps the biggest lifestyle change you can make is diet. Napoli cites a large study that sampled groups of Australians, Greeks and Scandinavians. “After following them for a few years, the researchers found that diet was linked to the state of their skin, regardless of skin type,” she says. “Those who had the least amount of visible aging ate a diet most similar to the Mediterranean diet.”

That means lots of fish, fruits and vegetables of all colors, whole grains, and olive oil rather than butter. Such a diet is rich in vitamin C and other antioxidants, which protect skin against damaging free radicals. It's also high in omega 3s—plentiful in fish, flaxseed and nuts—which help skin stay supple.

Most important, Napoli says, is limiting refined carbohydrates, such as sugar, white rice and white flour. “Refined carbs cross-link with the protein in collagen and stiffen it. It gives the skin an aged appearance.”

Adopting a Mediterranean diet benefits your whole body. “What nourishes our skin, nourishes our brain and our heart,” Napoli says. And it’s never too late, she insists. Make dietary changes now, and although existing sun damage won’t go away, you’ll help safeguard your skin against further ravages of time and environment.