Beauty runs deeper than idioms suggest: Your skin reflects your body's health, and what you eat makes a noticeable difference on the surface. "Dietary fat determines what kind of cellular membranes you have," says Anne Marie Fine, NMD, of Scottsdale, Arizona. "Omega-3s really help your skin look nice because they make the membranes of the cells more flexible, producing supple, elastic skin." Fine recommends eating up to three servings of cold-water fish, such as wild salmon or mackerel, per week or supplementing with 2-3 grams of omega-3-rich fish oil or flaxseed oil per day.

Vitamin E is also crucial for skin health. Because it distributes better between skin layers when ingested, vitamin E is more effective when taken as a supplement rather than applied topically, according to a 2006 study published in the British Journal of Nutrition. "Vitamin E is a potent antioxidant and retards the DNA damage of the cells from sun, pollution, and chemicals," says Arora. A handful of almonds or hazelnuts will satisfy your daily 9-28.5 IU requirement, but also consider incorporating vitamin E-rich foods like soybeans, olive oil, and rice bran into meals.