Why you need it: Vitamin C stimulates skin's own production of collagen -- the cushiony stuff that keeps skin firm and smooth, says Lisa Drayer, M.A., R.D., author of The Beauty Diet. More proof: A recent study published in the American Journal of Clinical Nutrition shows that a diet high in the vitamin correlates to less dryness and fewer wrinkles. Eat it: Kiwi
"Kiwi is one of the best sources of vitamin C," says Drayer, who recommends eating one a day. Not a fan of the tropical fruit? Substitute vitamin C-rich red pepper, broccoli, grapefruit, or oranges.
Look for a topical product that contains ascorbic acid, a stable (read: potent) form of the vitamin. Find it in Philosophy Time in a Bottle Daily Age-Defying Serum ($74; philosophy.com).
Why you need it: Zinc is an essential mineral needed for collagen production -- something that our bodies can't produce on their own.
Eat it: Serve up a cup of a low-fat plain yogurt. (Sorry, the frozen variety doesn't count.) In addition to zinc, it's also high in protein, another crucial component of collagen. Boost it: Swap out your regular tub for the Greek variety. "It has approximately double the amount of protein compared to their non-Greek counterparts," Drayer says.
Keep skin soft and supple with a moisturizer that contains the dairy product. Find it in Korres Greek Youghurt Advanced Nourishing Sleeping Facial ($32; sephora.com).
Why you need it: The stuff that gives dark-color fruit its deep blue or black color is also a super-potent antioxidant, says Lisa Young, R.D., author of The Portion Teller. Antioxidants neutralize cell-damaging free radicals unleashed by environmental aggressors, such as UV light and pollution.
Eat it: Just one half cup of blueberries contains enough of the antioxidant, but to reap the benefits, you'll need to eat them daily, Young says.
Look for skincare products with ceramides, essential skin lipids. Try CeraVe Facial Moisturizing Lotion PM ($14; cvs.com).
Why you need it: Water supports skin's elasticity, which gives skin its ability to stretch and snap back -- not sag.
Drink it: Have a hard time with plain H2O? Consider decaffeinated herbal teas or water-rich fruits and vegetables such as watermelon and cucumber, Young says.
Drive more moisture into your cells with a treatment that contains hyaluronic acid, which can hold 1,000 times its weight in water. Try Clinique Dramatically Different Moisturizing Lotion+ ($26; Clinique.com).