The great-skin diet

All sorts of supplements, special eating plans and complexion drinks promise glowing skin from the inside out. But not everything that is being dished out is based on science. We digested the research and polled experts to determine which foods to add to your diet to truly benefit skin, which may be worth an occasional munch and which to pass up. Get ready to eat, drink and be beautiful!

Proven complexion perfecters

Pile these on your plate. All pack nutrients essential for healthy skin.

Strawberries, citrus fruits, red peppers, broccoli

Beauty benefit: a smooth texture

Eat-right evidence: Vitamin C, plentiful in this produce, is vital for the production and formation of collagen, skin's support structure, says Toby Amidor, R.D., director of nutrition for DietTV.com in New York City. And a strong support layer helps smooth what's on top and prevent wrinkles, she says. Aim for: two 1-cup servings of fruit and 1 cup of red peppers and/or broccoli a day

Sunflower seeds and almonds

Beauty benefit: sun protection

Eat-right evidence: These seeds and nuts are loaded with vitamin E. Collectively, antioxidants act like an army, protecting skin from UV-spawned free radicals. But E is on the front lines; skin's top layers contain high levels that guard cells' outer membrane so cells stay healthy. Plus, strong membranes hold water in, keeping skin hydrated. Aim for: 2 tablespoons hulled seeds or 23 almonds daily

Dark orange, leafy green and red veggies

Beauty benefit: a fresh complexion

Eat-right evidence: Squash, sweet potatoes and spinach are full of the antioxidant beta-carotene. Your body converts it to vitamin A, which regulates cell production and turnover so skin's surface is smooth, says Valori Treloar, M.D., coauthor of The Clear Skin Diet (Cumberland House Publishing). Carotenoids may also decrease skin's sensitivity to sun. Aim for: three 1-cup servings a day

Fortified cereal, lean meat, pork, poultry, oysters

Beauty benefit: a youthful glow

Eat-right evidence: You'll get zinc and iron, minerals key to skin functioning. Zinc contributes to cell production, plus natural cell sloughing, which keeps dullness at bay. Red blood cells need iron to carry oxygen to skin, helping give you a glow, says David Bank, M.D., a derm in Mount Kisco, New York. Aim for: 1 serving of cereal (a cup), 1 palm-sized serving of meat or poultry or 3 oysters per day

Water

Beauty benefit: dewy skin

Eat-right evidence: Skin cells contain mostly water, and if you're dehydrated, skin will look and feel parched, too. But you needn't chug 8 cups a day; University of Pennsylvania researchers found no studies to back up the recommendation. Simply ward off dehydration—and dryness—by drinking when you're thirsty. Aim for: 6 cups a day. It's a good starting point, says Keri Gans, R.D., of NYC.

Smart skin suggestions

New research hints at these foods' beauty power, but effects aren't totally proven yet. No need to wait, though; the goodies are part of a healthy diet.

Wild salmon, Atlantic mackerel, walnuts

Beauty benefit: fewer wrinkles

Eat-right evidence: These fish and nuts, plus fortified eggs, are bursting with omega-3 fatty acids, which fight inflammation in the body caused by sun and stress. "Inflammation produces free radicals, and free radicals contribute to aging by attacking collagen," says Susan Taylor, M.D., a dermatologist in Philadelphia. But research still needs to connect the dots definitively and show that the anti-inflammatory abilities of omega-3s translate to younger-looking skin, she says. One study did find that older people who consumed more fish and veggies over their life had fewer wrinkles than those who ate more meat, the Journal of the American College of Nutrition reports. The research didn't focus solely on fish, however; vegetables' antioxidants, for example, may have been a factor. Aim for: two 5-ounce servings of fish per week; on other days, 1 oz of walnuts or 2 omega-3 eggs

Whole wheat and grains

Beauty benefit: clearer skin

Eat-right evidence: In the past, derms have maintained that unless you wipe greasy fingers on your face, food doesn't cause zits. But some are rethinking the party line: Australian researchers found that a low-glycemic diet (more whole grains, protein and produce versus refined carbs such as white bread) may reduce acne. One explanation: Low-glycemic foods keep insulin steady, and refined carbs and sugar spike it. The surges may boost production of androgens, hormones that, when elevated, can cause zits. After 12 weeks of a low-glycemic diet, subjects' pimple counts dropped 20 percent, a study in The American Journal of Clinical Nutrition notes. More studies are needed to prove the link, but no doctor will discourage you from eating whole grains and veggies! Aim for: 3 servings a day (one serving equals a slice of bread or 1/2 cup cooked grains)

Today's special: gorgeous skin If your complexion could choose everything you ate for the day, here's what would be on the menu, says Keri Gans, R.D., who put together this plan.

Breakfast

• 1 cup whole-grain, fortified cereal such as Total
• 1 cup skim milk
• 1 cup sliced strawberries or 1 medium grapefruit
• 1 cup green tea

Lunch

• Grilled chicken sandwich
• 5 oz chicken breast
• 2 slices whole-grain bread
• 2 slices tomato
• 1 leaf lettuce
• 1/8 of avocado
• 1 tsp mustard
• 1 medium apple

Dinner

• 5 oz wild salmon
• Spinach salad
• 2 cups fresh spinach
• 1/2 cup sliced red bell pepper
• 1/2 cup chopped tomato
• 1/2 cup broccoli
• Toss with 1 tbsp each olive oil and balsamic vinegar
• 1 medium baked sweet potato

Snacks/dessert

• 8 oz nonfat plain yogurt or 1 part-skim string cheese
• 1 oz sunflower seeds
• 1 small orange or 1 cup baby carrots
• 1 oz dark chocolate or 1 glass red wine

Beauty treat or trouble?

Guess if the following foods are good or bad for your skin—and find out the reasons why.

Sweets

Trouble Chowing candy and other sugary snacks may make you feel like a kid, but it's likely aging you. The rush of glucose into your bloodstream sets off a process known as glycation, in which sugars attach to proteins and form advanced glycation end products (AGEs). These molecules naturally build up in skin as you get older, but the more sugar you eat, the more AGEs you have. Bad news: They cross-link with collagen and elastin fibers, making the normally resilient tissues weak or inflexible, Dr. Bank says. And skin that doesn't bounce back easily leads to wrinkles and sagging. In fact, the study showing fish lovers had fewer wrinkles revealed the opposite for those with a sweet tooth.

Dark chocolate

Treat Although there might be some truth to the claims that sugar-laden chocolate contributes to acne (and wrinkles), the high-quality, dark variety—70 percent or more cocoa—may actually be good for your skin. Preliminary studies found that cocoa's flavonols (a potent type of antioxidant) can help increase blood flow, supply skin with oxygen, improve skin hydration and reduce sun sensitivity. But dark chocolate is high in calories, so treat yourself to only 1 oz a day.

Milk

Trouble Got acne? Milk may not be doing your skin good. Three new studies have found a connection between teens' milk intake and pimples. This could potentially translate to adults; however, it's not been proven. More research is under way, but the probable explanation is hormone-related. Androgens naturally found in milk (even organic versions without added hormones) may add to a drinker's own level of androgens, which are associated with oily skin and acne. Milk also raises insulin levels and contains growth factors that act like insulin, Dr. Treloar says. Both may lower the production of molecules that bind to and deactivate hormones—meaning there may be more free-roaming androgens able to cause pimples. It's too early to prescribe a dairy ban for anyone zit-plagued. But it may be worth experimenting with a milk-free diet if you have excessive, stubborn breakouts, Dr. Treloar says. (Be sure, however, to take a calcium supplement with vitamin D.)

Spicy foods

Trouble Rosacea sufferers know to avoid five-alarm meals. But if you have fair, sun-damaged skin, hot-and-spicy foods may lead to the condition or to a red, blotchy complexion. "UV exposure weakens blood vessel walls. If your skin then repeatedly flushes, which swells vessels, they may not be able to shrink back down," Dr. Treloar says.

Wine

Treat Reds are rich in polyphenols, antioxidants that help fight skin-damaging free radicals. But sip no more than one glass a day, says Katherine Brooking, R.D., of NYC. Excessive alcohol halts your body's release of its antidiuretic hormone. As a result, you make extra visits to the ladies' room and end up not only feeling dehydrated, but having skin that looks dry, with a dull tone and more visible wrinkles. So enjoy wine in moderation—and make a toast to great skin! Cheers!...