Do food company execs sit around all day dreaming up ways to make us think we need something—snack bars, sports drinks, “nutritional drinks,” whatever—that we could do without? Or trying to convince us that products havemoreof something—fruit, vegetables, you-name-it—than they do? There’s a sucker born every minute, they say. And these companies are out to prove it. Could staying active lower your risk of Parkinson’s disease? Can drinking more fluids help prevent recurring urinary tract infections (UTIs)? Until recently, no one had looked. Can eating organic foods lower your risk of cancer?