Solid friendships can help buffer life's stress. iStockphoto hide caption

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Colleen Frainey, 16, of Tualatin, Ore., cut back on advanced placement classes in her junior year because the stress was making her physically ill. Toni Greaves for NPR hide caption

itoggle caption Toni Greaves for NPR

With osteoarthritis, knees become swollen and stiff, and cartilage can degenerate. Ted Kinsman/Science Source hide caption

itoggle caption Ted Kinsman/Science Source

Kombucha made by artisan tea brewer Bill Bond in Akron, Ohio, comes in an array of flavors, such as lemongrass, ginger, blueberry and watermelon. Peggy Turbett/The Plain Dealer /Landov hide caption

itoggle caption Peggy Turbett/The Plain Dealer /Landov

Differences in brain chemistry can affect an individual's likelihood of weight gain. Katherine Streeter for NPR hide caption

itoggle caption Katherine Streeter for NPR

Candy-flavored cigars like these in a shop in Albany, N.Y., are the focus of efforts to restrict sales of sweet-flavored tobacco. Hans Pennink/Associated Press hide caption

itoggle caption Hans Pennink/Associated Press

Sally O'Neill decided to have a double mastectomy rather than "do a wait-and-see." Richard Knox/NPR hide caption

itoggle caption Richard Knox/NPR

Michael Pagliaro, left, laughs with Paul Scattaretico at the Muzic Store Inc. in Dobbs Ferry, N.Y., as Pagliaro picks up instruments for his rental business. Before Pagliaro had a hip replacement, pain made it difficult to work. Maggie Starbard/NPR hide caption

itoggle caption Maggie Starbard/NPR

Depression is common among old people, affecting up to 25 percent. iStockphoto.com hide caption

itoggle caption iStockphoto.com

Mike Jackson has diabetes and high blood pressure. His eye was damaged after he cut back on insulin because he couldn't afford it. Bryan Terry for NPR hide caption

itoggle caption Bryan Terry for NPR

Going to the doctor may be uncomfortable for people who are worried about weight. iStockphoto.com hide caption

itoggle caption iStockphoto.com