New York City will soon eat less salt, if Mayor Mike Bloomberg has his druthers. Bloomberg plans to unveil a new health initiative Monday aimed at encouraging manufacturers and restaurant chains to reduce the amount of salt in their food by 25 percent over the next five years in order to curtail high blood pressure and prevent some strokes and heart attacks associated with that condition. The plan allows companies to cut the salt gradually, is voluntary, and doesn't require legislation, but would require national cooperation from major food companies, as it's impractical to expect them to change their products just for New York. The city's previous campaign against trans fats began as a voluntary plan, but when that didn't work, legislation was passed to force restaurants to eliminate trans fat from their menus. It wouldn't be easy to legislate salt, though, its diverse uses as a flavor enhancer and preservative mean that removing it from some products is complicated.