New York Mayor Michael Bloomberg — who is known to shake salt on his pizza — is focusing on sodium as the next unhealthy enemy in his crusade to coax people into eating better.

Bloomberg’s health department has already banned trans fats in restaurant meals and forced chain eateries to post calorie counts on menus. The city set guidelines recommending maximum amounts of salt for a variety of restaurant and store-bought foods, with the goal of cutting salt levels in food by a quarter overall in five years.

Unlike the city’s trans fat ban and calorie count rule, the salt initiative is voluntary.

The recommendations posted on the city health department’s website call for substantial reductions in the salt content of many products, from a 20 per cent drop in peanut butter to a 40 per cent decline in canned vegetables. The targets include a 40 per cent reduction in breakfast cereals and flavoured snack chips, and a 25 per cent reduction for cold cuts, processed cheese and salsa.

Not even the mayor’s favourite foods — popcorn and hot dogs — were spared: The city wants food manufacturers to work on reducing salt by 30 per cent in popcorn and 20 per cent in wieners.

Health officials say Americans now eat about twice the amount of salt they should. Too much sodium contributes to high blood pressure, which can cause heart attack and stroke.

New York City’s programme is modelled in part after a similar initiative in Britain that has been under way since 2003.