When it comes to my skin, I’m vain. But who isn’t? I’ve yet to meet someone—especially a woman—who hasn’t ever aired a complaint about a pimple, dry skin, a sun spot, a wrinkle or [go ahead, insert your skin issue here].
Here’s the good news: you may be able to solve some of your skin “issues” with food. Eating food, that is, not slathering it on your skin (though, in some cases, that might work, too, but as a registered dietitian I can’t offer any advice there).
Related: 20 Foods for Beautiful Skin 
If you want smoother skin, try...
Grapefruit. Pick a pink one, though, because pink grapefruit gets its pink-red hue from lycopene, a carotenoid that may help to keep your skin smooth. In a study published in 2008 in the European Journal of Pharmaceutics and Biopharmaceutics, researchers found that of the 20 individuals studied, those who had higher skin concentrations of lycopene had smoother skin. You can also get lycopene from tomatoes, carrots, watermelon, guava and red peppers.
Other food solutions: cocoa. Cocoa (and tea and red wine) contain a type of flavonoid called epicatechin. In a study of 24 women, published in the Journal of Nutrition, drinking an epicatechin-rich cocoa beverage daily for 12 weeks improved skin texture. The authors explained that epicatechin increased blood flow to the skin, boosting nutrient and oxygen supply—both factors essential for keeping skin healthy.
If (age-related) dry skin is your problem, try...
Strawberries. Eating more vitamin C-rich foods, such as strawberries, may help to ward off age-related dryness (wrinkles, too!), suggests research from 2007 in the American Journal of Clinical Nutrition. Vitamin C’s skin-smoothing effects may be due to its ability to mop up harmful free radicals produced from ultraviolet rays and also its role in collagen synthesis. Collagen is fibrous protein that keeps skin firm and vitamin C is essential for collagen production. Other C-rich foods include grapefruit, oranges, cantaloupe and dark green leafy vegetables.
Recipes to Try: Healthy Sweet & Savory Strawberry Recipes 
If you’re worried about wrinkles, try...
Edamame. Eating edamame and other soyfoods may help to preserve skin-firming collagen because it is rich in isoflavones. In a study published in the Journal of the American College of Nutrition, mice fed isoflavones and exposed to ultraviolet radiation had fewer wrinkles and smoother skin than mice that were exposed to UV light but didn’t get isoflavones. The researchers believe that isoflavones help prevent collagen breakdown, which begins starting in our twenties.
Other food solutions: sardines. EPA (eicosapentaenoic acid), one of the omega-3 fats in fatty fish like sardines, has also been shown to preserve collagen.
Related: Dr. Oz’s 3 Secrets to Beating Your Age 
If you’re prone to sunburn, try...
Tomatoes. Consuming more lycopene—the carotenoid that makes tomatoes red—may protect your skin from sunburn. In one study, participants who were exposed to UV light had almost 50 percent less skin reddening after they ate 2 1/2 tablespoons of tomato paste or drank about 1 2/3 cups of carrot juice daily, in addition to their regular diet, for 10 to 12 weeks. Supplements, however, weren’t as effective: in the same study, those who received a lycopene supplement or synthetic lycopene weren’t significantly protected against sunburn.
Other food solutions: Corn and egg yolks. Both are excellent sources of lutein, another type of carotenoid. Like lycopene, lutein also shields your skin from UV damage.
If skin cancer is your concern, try...
Salmon. The omega-3 fats DHA and EPA (docosahexaenoic and eicosapentaenoic acids, respectively) found in salmon may shield cell walls from free-radical damage caused by UV rays, according to a 2009 study in the American Journal of Clinical Nutrition. Researchers followed the eating habits of more than 1,100 Australian adults for approximately five years and found that for those who ate a little more than 5 ounces of omega-3-rich fish—such as salmon, sardines and tuna—each week the development of precancerous skin lesions decreased by almost 30 percent. Aim to eat two servings of fatty fish each week: not only are the omega-3s good for your skin, they’re good for your heart too.
Recipes to Try: Easy Salmon Cakes and More Healthy Salmon Recipes 
Other food solutions:coffee and tea. Research suggests caffeine in the two beverages may help to protect your skin against skin cancer. Caffeine basically kills precancerous and ultraviolet-damaged skin cells by blocking a protein that they need to divide, explains Paul Nghiem, M.D., Ph.D., associate professor of dermatology at the University of Washington Medical School. In a study where mice were exposed to harmful sunburn-causing ultraviolet B rays, caffeine inhibited the formation of skin tumors.
What foods do you eat to help your skin?
Related Links from EatingWell: