Salt must soon be on the menu — very visibly — at hundreds more chain restaurants in New York City, after a court on Thursday cleared the way for the city to enforce a rule requiring many eateries to alert consumers to food items with high salt content.
Some chains, such as Applebee’s, T.G.I. Friday’s and Subway, have voluntarily started including the menu icon — a saltshaker in a triangle — with an explanation that items that bear the symbol contain more than 2,300 milligrams, or about a teaspoon, of salt, the daily limit recommended by many nutritionists.
But other chains have held back, and the National Restaurant Association, a trade group, said it would continue a court challenge to the rule, which was approved by the Board of Health last year. The rule went into effect in December, but a court ruling blocked the city from enforcing it. The Appellate Division of the New York State Supreme Court lifted the enforcement ban.
“This is really important to the health of New Yorkers,” Dr. Mary T. Bassett, the city’s health commissioner, said. “We will be able to ensure that New Yorkers have the information they need to make better decisions about what they eat.”
Dr. Bassett said excessive amounts of salt in the diet can lead to high blood pressure, which is considered a risk factor for heart disease and stroke. Health department officials said that on average New Yorkers consume considerably more than the recommended amount.
The labeling rule applies to restaurants with at least 15 stores nationwide, as well as to some theater chains and some vendors in sports stadiums. The health department said that about 3,000 chain restaurants in the city would be affected by the rule. The symbol will appear on menus and menu boards, although some restaurants might not sell items that exceed the limit and therefore will not display the symbol.
The restaurant industry said the costs of implementing the rule would be a burden to restaurant owners, including franchisees who may operate just one or two outlets. An industry official also worried about how customers might interpret the saltshaker symbol.
“You have a radioactive symbol for an essential nutrient,” said Christin Fernandez, a spokeswoman for the National Restaurant Association, which is based in Washington. “This is the first of its kind. It looks like a poison symbol.”
Dr. Bassett said that high salt content had been found in some unlikely places, including a salted caramel milkshake. Some chains had modified their offerings to reduce salt content and avoid having to place the saltshaker symbol next to a menu item, she added.
The menu labeling rule represents a foray by Mayor Bill de Blasio, a Democrat, into territory pioneered by his predecessor, Michael R. Bloomberg, who often drew fire from the restaurant industry over pushes to police New Yorkers’ diets.
Mr. Bloomberg, a political independent, ordered chain restaurants to list the number of calories for each menu item in the hopes of fighting obesity. He banned most uses of trans fats in restaurants. And he tried to halt the sale of large soft drinks — a move that was successfully challenged in court by the restaurant industry. He also led an initiative to get food companies to voluntarily reduce the amount of salt in processed foods sold at grocery stores.
The fine for not complying with the menu labeling rule is small — just $200 — but Thomas Merrill, the general counsel of the health department, said that restaurants risked losing their permits if they did not meet the requirement.
An earlier version of this article, using information from city officials, described incorrectly the salt consumption habits of New Yorkers. On average, New Yorkers consume considerably more salt than is recommended, not 40 percent.