First New York City required restaurants to cut out trans fat. Then it made restaurant chains post calorie counts on their menus. Now it wants to protect people from another health scourge: salt.

On Monday, the Bloomberg administration plans to unveil a broad new health initiative aimed at encouraging food manufacturers and restaurant chains across the country to curtail the amount of salt in their products.

The plan, for which the city claims support from health agencies in other cities and states, sets a goal of reducing the amount of salt in packaged and restaurant food by 25 percent over the next five years.

Public health experts say that would reduce the incidence of high blood pressure and should help prevent some of the strokes and heart attacks associated with that condition. The plan is voluntary for food companies and involves no legislation. It allows companies to cut salt gradually over five years so the change is not so noticeable to consumers.