A tiny salt shaker symbol that warns certain meals are high in sodium will appear, starting Tuesday, on menus in chain restaurants in New York City, the first U.S. city to take the step in an effort to combat heart disease and stroke.

Any menu item containing more than 2,300 milligrams (0.08 oz) of sodium, the daily limit many nutritionists recommend and which equals about one teaspoon of salt, must display the emblem of a salt shaker in a black triangle.

The measure unanimously approved by the New York City Board of Health in September applies only to restaurants with at least 15 establishments across the U.S., and concession stands at some movie theaters and sports stadiums.

"It's not hard to get 2.3 g of sodium into your face," Dr. Howard Weintraub, co-director of NYU Langone Center for the Prevention of Cardiovascular Disease, said on Monday.

The new menu labels may be an eye opener for customers who flock to chains such as Chipotle and Subway, which are perceived to be more healthy. Until Tuesday, they may have been blissfully unaware of the sodium content of a Chipotle loaded chicken burrito (2,790 mg), Subway's foot-long spicy Italian sub (2,980 mg), TGI Friday's classic Buffalo Wings (3,030 mg) or Applebee's grilled shrimp and spinach salad (2,990 mg).

Cardiovascular disease is the leading cause of death in New York City, claiming nearly 17,000 lives in 2013, the health department said. It noted a "well-established connection" between sodium intake and high blood pressure, a major risk factor for heart attack and stroke.

A 2010 study found New Yorkers consume more than 3,200 mg of sodium each day on average, with higher intake among blacks and Hispanics, the health department said.
Getting New Yorkers to start watching their sodium intake, is a first step that health advocates hope will prompt other behavioral changes.

"Things are not going to work out great if all you do is just not eat salt," Weintraub said. "But maybe, just maybe, they'll start to watch how much they eat, maybe they will get off the subway a stop earlier and walk, instead of taking the elevator, they will walk two flights, there will be some weight loss."

The sodium warning label pressed by Mayor Bill de Blasio echoed a series of efforts by his predecessor, Michael Bloomberg, including banning smoking in public places and requiring fast food joints to post calorie counts.