While the links between good nutrition and holistic well-being are well established, A growing number of researchers are tracing specific connections between poor diet and poor mental health—including depression. It's a relationship that's getting attention from big backers, too—including a major project from the European Union, and a trial from the U.S. Dept. of Defense to boost the nutrition of former soldiers in an attempt to stem veterans' high suicide rates. Solid evidence is mounting that the high-fat, high-sodium, high-sugar diet of the fast-food crazed West is doing damage not only to our collective waistline, but also our mental health and happiness.

And the cost of this—culturally, personally, and financially—is very painful. The BBC's David Robson reports: "For [Australian researcher Felice] Jacka, a break in our love affair with fast food can't come quickly enough. According to some predictions, nearly half of all Americans ...