WASHINGTON (Reuters) - Popular low-carbohydrate diets are leading Americans to poor health and are spawning a rip-off industry of "carb-friendly" products, health experts and consumer advocates said on Tuesday. They announced a new group, called the Partnership for Essential Nutrition, to help educate Americans about the need for healthy carbohydrates such as vegetables, fruits, beans and whole grains. "When unproven science becomes a sales pitch, some people get rich and the rest of us get ripped off," Jeffrey Prince of the American Institute for Cancer Research told a news conference. "Eating vegetables, fruits, whole grains and beans, which are all...