NEW YORK (Reuters) - A New York judge on Wednesday shot down a challenge by a restaurant trade group and upheld a city rule requiring many chain eateries to post warnings on menu items that are high in sodium.

The rule, believed to be the first of its kind in the United States, mandates restaurants with 15 or more locations nationwide to post a salt shaker encased in a black triangle as a warning symbol next to menu items with more than 2,300 milligrams of sodium, the daily limit recommended by many nutritionists.

Dishes that have been flagged include Chipotle's loaded chicken burrito and Applebee's grilled shrimp and spinach salad.

"Information is power," Justice Eileen Rakower of New York state Supreme Court in Manhattan said in a ruling from the bench. Unlike the city's unsuccessful large-soda ban, she said, the rule did not restrict the use of sodium.

New York City adopted the rule, which took effect in December, to help lower blood pressure and reduce the risk of heart attacks and strokes.

The National Restaurant Association, a restaurant trade group, then sued the city's Board of Health saying the rule unfairly burdened restaurant owners.

In court on Wednesday, Rakower denied the group's motion for a preliminary injunction to stop enforcement of the rule. Starting March 1, violators will be punished by $200 fines.

In addition to chain restaurants, the rule also applies to concession stands at some movie theaters and sports stadiums.

"This is really good news for the health of New Yorkers," Dr. Mary Travis Bassett, the city's health commissioner, said outside the courthouse.

S. Preston Ricardo, a lawyer for the restaurant group, said the association intended to appeal.

In court, Ricardo argued the rule was arbitrary and harmful. "It's just enough information to cause consumers to be confused and ill-informed," he said.

The warning was proposed under New York City Mayor Bill de Blasio, but the restaurant group likened it to former Mayor Michael Bloomberg's failed effort to curb sales of sugary drinks larger than 16 ounces.

The National Restaurant Association calls itself the world's largest food service trade association, counting more than 500,000 restaurant businesses as members.

The case is National Restaurant Association v. New York City Department of Health & Mental Hygiene et al, New York State Supreme Court, New York County, No. 654024/2015.

(Reporting by Karen Freifeld; Additional reporting by Jonathan Stempel; Editing by Anthony Lin and Andrea Ricci)