It's not just kombucha and yogurt: Probiotics are now showing up in dozens of packaged foods. But what exactly do these designer foods with friendly flora actually offer — besides a high price tag? Saul Loeb/AFP/Getty Images hide caption

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Scientists have documented that beneficial microorganisms play a critical role in how our bodies function. And it's becoming clear that the influence goes beyond the gut — researchers are turning their attention to our emotional health. iStockphoto hide caption

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Prozac In The Yogurt Aisle: Can 'Good' Bacteria Chill Us Out?

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Biologist Rob Knight, co-founder of the American Gut Project, recently moved the project to the University of California, San Diego's School of Medicine. Casey A. Cass/University of Colorado hide caption

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A probiotic commonly found in yogurt seems to help women lose more weight and fat, a recent study finds. But you still have to eat healthy to see an effect. iStockphoto hide caption

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You tried burping. You tried bouncing. You tried swaddling. Now what? iStockphoto hide caption

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Can Probiotics Help Soothe Colicky Babies?

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Billie Iverson, 86, of Cranston, R.I., recently underwent a transplant of intestinal microbes that likely saved her life. Ryan T. Conaty for NPR hide caption

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Microbe Transplants Treat Some Diseases That Drugs Can't Fix

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Gut Bacteria's Belch May Play A Role In Heart Disease

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Microbiologist Emma Allen-Vercoe invented the Robogut, a mechanical device that mimics conditions in the human colon. Courtesy of thestar.com hide caption

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Packages of Activa yogurt, which contain probiotics, on a grocery shelf in Chicago. M. Spencer Green/AP hide caption

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Confusion At The Yogurt Aisle? Time for Probiotics 101

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