New York is set to become the first city in the US to ban all but tiny quantities of trans fats from being used in its 24,000 restaurants. According to plans agreed this week by the board of health, under the mayor, Michael Bloomberg, all the city's restaurants, cafes and street stalls will be forced to keep to a limit of half a gram of trans fats in any item served from their menus.

The move will see a sharp drop in use of the treated fats. One serving of chips contains up to eight grams.

Trans fats have been the subject of mounting concern among health experts who warn that the fats could contribute to heart disease by raising blood cholesterol levels. In a process known as hydrogenation the fats are formed by subjecting oils to high temperatures, which stabilises and solidifies them and makes them last longer. They are used in the baking of cakes, doughnuts and bread, and for deep frying.

Health campaigners say the fats have no nutritional value and can raise the risk of heart disease, a condition that kills 18,000 New Yorkers under the age of 65 each year.

The city's board of health has set a deadline in December for consultation. Restaurants will then have until July to prepare and switch to oils or margarine with less than half a gram per serving. The health board said the move would be "cost neutral" as alternatives could be bought at the same price.

The issue of trans fats is particularly sensitive in New York, which has by far the greatest density of food outlets of any US city, about half of which still use trans fats. New Yorkers tend to eat out or have takeaways more regularly than most Americans. But the city also prides itself as being the nation's "thought-leader" on health issues: it was the first to ban lead in paint (in 1960), and its lauded smoking ban in restaurants three years ago has been widely copied throughout the US.

The action against trans fats was, however, condemned by the New York State Restaurant Association, which represents 3,500 city restaurants. The group's vice president, Charles Hunt, said that compared with smoking, which made other people passive victims, this was an issue entirely of personal choice. He said: "You chose what you eat and that only affects you. We don't think it's appropriate for a non-elected body such as the health board to make a decision that will have a big effect on restaurants across New York City."

Denmark is the only country so far to have moved against trans fats. Chicago has floated the idea of restrictions but these would apply only to large food chains with annual sales worth more than $20m. Recently the city authorities indicated they were minded just to opt for voluntary measures.

New York has tried a year-long educational drive to persuade outlets to shift voluntarily from trans fats, but the board of health concluded the campaign had minimal impact. Some big US food chains, including Starbucks and Wendy's, have indicated they will restrict trans fats.