OLLEGE PARK, Md., Nov 29 (Reuters) - Public health advocates on Thursday called for tighter restrictions on salt content in food, arguing that cutting the nutrient's overuse by most Americans could save thousands of lives annually. Excessive salt in Americans' diets is a major factor in high blood pressure and increases risk for heart disease, while most Americans exceed recommended limits, according to health experts. The Center for Science in the Public Interest (CSPI) cited these factors in urging stricter regulation by the U.S. Food and Drug Administration at a public hearing, held on Thursday at the FDA. Trimming the...