New York could become the first city in the nation to put warning labels on high-sodium items on chain restaurant menus.

Under a proposal  presented Wednesday at a New York City Board of Health public meeting, any restaurant chain with 15 or more locations must add a warning icon alongside menu items that contain more than 2,300 milligrams of sodium, roughly equivalent to about one teaspoon of salt.

“The American Heart Association sees this proposal as an opportunity to help people make more informed food choices while eating out so they can live a healthier life,” said AHA CEO Nancy Brown. “This level of sodium should not be exceeded in an entire day, and consuming that amount (or more) in a single meal would set up an individual to be well in excess of recommended healthy amounts.”

Americans currently consume more than 3,400 milligrams of sodium daily, more than double the amount recommended by the AHA for ideal cardiovascular health.

Health studies show that about 77 percent of the sodium Americans consume comes from packaged and restaurant foods. Increased sodium intake leads to elevated blood pressure, which is a leading risk factor for strokes and heart disease.

Dr. Lawrence Appel, a professor at Johns Hopkins University’s medical school, calls sodium “a stealth nutrient.”

“Most people think it comes from a salt shaker, but the vast majority of our sodium is put in food before we have an opportunity to decide ourselves,” said Appel, who directs the university’s Welch Center for Prevention, Epidemiology and Clinical Research.

Appel called the health board’s recommendation “a great step forward in educating people about the major sources of sodium.”

Currently, most restaurant menus have very little detail on their menus about the nutritional value of their items, outside of an occasional heart-shaped or leaf icon to indicate entrees that the business deems “healthy.”

Requiring a warning label could be just the incentive that chain restaurants need to make healthier changes to their menu offerings.

“If this gets enacted, companies are going to do whatever they can to stay below that 2,300 mark. They will not want to have that label,” he said.

One-third of all American adults have hypertension, Appel said. Another one-third are “pre-hypertensive,” meaning they are at high risk for getting high blood pressure.

“Your lifetime risk of developing hypertension is 90 percent, so this is a massive public health problem,” he said. “And that’s why you do these kind of public health campaigns, to deal with the source.”

Appel said the awareness component of such warnings could also have an impact that reaches beyond the Big Apple’s borders.

New York’s health board was the first entity to propose that chain restaurants require both calorie counts and eliminate artificial trans fat from their food.

“When it comes to public health policy, I think New York City is leading the pack. They’re a trendsetter,” Appel said.

Having the board make such a requirement could send a signal to other regions in the nation to do the same, as well as the federal government. It also could have an impact on the restaurant behavior elsewhere.

“These companies with more than 15 [outlets] are often national and international companies, so if they can do it in New York, it can be done elsewhere, it’s just a matter of having the public policies in place,” he said.

Michael Jacobson, executive director of the Center for Science in the Public Interest, also applauded what he described as a “bold move” by New York.

“Most people would never pour a whole teaspoon of salt on any single dish, so shouldn’t people be warned when restaurants are secretly doing that for them?” he said in a statement, adding that “sensible warning notices” will also prompt restaurants to use less salt.

If the board votes to consider the warning proposal, it will open a public comment period over the summer and, if approved, the sodium icons could appear on menus by the end of the year.