What's up with that? you wonder during the recent commercial in which Diane Keaton, with her famous grin, hawks a new skin cream by flexing her well-toned biceps. Muscles selling moisturizers? The spot, for L'Oreal Paris Age-Perfect Pro-Calcium Restorative Hydrating Cream, links bone-building with skin-boosting. Right, the calcium — and other vitamins — are good-for-skin story. But don't tune out: The story becomes more intriguing. Vitamins and supplements are now the fastest-growing segment of the antiaging skin-care market. While cosmetics companies have offered vitamin-enriched creams and serums for several years now, the latest trend is to focus on the pill itself. Leading brands like Kinerase, Olay, and N. V. Perricone M.D. have all introduced beauty capsules, claiming they can do from the inside what a cream can't do from the outside. The right beauty vitamin, believes Rachel West, a California-based osteopath, "can get your inner body functioning at an optimal level, which is then reflected in your skin, hair, and nails."

Is it any wonder that we'd be game for this form of quick fix? Between 1997 and 2002, the supplement industry experienced a 34 percent jump in sales to $19 billion annually. Given the choice to pop a pretty pill....

"The data keeps pouring in every day about the benefits of supplements," says Nicholas Perricone, M.D., a dermatologist and author of The Wrinkle Cure. Also a cosmeceutical pioneer with a highly successful product line, Perricone began his business with multivitamin packs and omega-3 capsules and has expanded into antioxidant powders, mushroom extracts, and peptide blends. He believes skin ages as a result of low-grade inflammation on the cellular level. Supplements, he says, can help combat this inflammation.

Despite their virtues, vitamins and supplements are considered food, not drugs, and therefore they are not regulated by the FDA. Still, it's hard to dismiss the extensive studies being presented within the dermatological community that reinforce the case for their skin-boosting abilities. A recent one in the Journal of Investigative Dermatology reported that some people who took vitamins C and E in the long term saw a reduction in visible premature aging.So why can't you just eat better to look better? "Foods we ate as little as 100 years ago had 10 times the nutrients they do today," says New York-based nutritionist Esther Blum, author of Eat, Drink, and Be Gorgeous. "But don't blame the farmers. To survive financially, they're driven to overuse the soil, which in turn depletes the minerals that once enriched the produce." Couple that with the fact that your blood ships most of the nutrients gleaned from food to major organs, like the heart and liver, first — leaving your hair, skin, and nails with the dregs — and you can understand why you need to do more than consume those "healthy" carbs, fats, and proteins.

So will the increasing number of vitamins and supplements on the market that target skin mean it will soon be time to junk those jars of expensive creams? Not quite yet. These so-called topicals work by penetrating the skin's dermis (bottom-most layer), and by plumping the surface and speeding up exfoliation. This is why cosmetics companies can claim that their potions promote a smoother complexion. But it's almost as difficult to accurately measure how many digested nutrients are reaching your hair, skin, and nails as it is to measure how deeply your products are penetrating from the other end. We say, hedge your bets by attacking on both fronts.

To know whether you're getting the optimum dosage for your skin type, it can't hurt to seek a professional opinion. What follows is a list of supplements you might incorporate into the daily feeding of your precious face:

USE ANTIOXIDANTS FOR ANTIAGING. Vitamins C and E, alpha-lipoic acid, selenium, and CoQ10 all fend off free radicals in the environment, preserving collagen and elastin (skin's "plumpers") and slowing fine-line accumulation.

"B" SMART ABOUT FIRM SKIN AND FORTIFIED HAIR AND NAILS. Even a mild vitamin-B deficiency will show up as brittle tips or slack skin.

TRY OMEGAS FOR ALPHA SMOOTHNESS. To calm irritation, consider essential fatty acids (omegas-3 and -6): Recent evidence suggests they can calm psoriasis, eczema, and acne.

HYDRATE WITH HYALURONIC ACID. We know it's successful topically. Taken orally, it may also help skin stay moist.

POLISH WITH PROBIOTICS. Lackluster skin may be a reflection of a compromised intestinal tract, says Blum. Probiotics can keep skin radiant by minimizing yeast overgrowth.

ZAP ZITS WITH ZINC. To regulate the oil production that can cause flareups, think zinc.

Vitamin brands deemed reputable by the experts interviewed for this piece include Standard Process; Twin Labs; Olay Vitamins; Innate; N.V. Perricone M.D.; Kinerase Multi-Vitamins, Minerals and Supplements; and Weil Nutritional Supplements. Available at health, drug, and online stores.

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