NEW YORK -- Subway riders, after being cautioned about smoking, sugar and teen pregnancy, are getting a new message: Pass on the salt.

The city's Department of Health launched an ad campaign Monday urging passengers to scrutinize the salt in packaged foods and choose those with less. The ad shows two loaves of bread and zooms in on the sodium line in their nutrition labels, showing that one loaf has more than twice the sodium of the other.

"Too much salt can lead to heart attack and stroke," the ad warns.

While the tone may be serious, the approach is relatively low key for a city that has shown subway riders photographs of a woman's amputated fingers to illustrate the hazards of smoking; other subway ads featured a soda bottle pouring out what looks like globs of fat to tell people, "Don't drink yourself fat." Teen-pregnancy-prevention ads on many subway trains now feature a toddler crying and admonishing a hypothetical parent about comparatively low high school graduation rates among teens with their own children.

The cost of the new salt campaign wasn't immediately available Monday evening. The city said the federal Centers for Disease Control and Prevention paid for part of it.

The city has nudged food manufacturers to reduce salt, promulgating voluntary salt guidelines in 2010 for various restaurant and store-bought foods. Mayor Michael Bloomberg announced this February that 21 companies have met targets so far. Heinz ketchup is 15 percent less salty than it was three years ago, for instance, and Kraft American cheese singles have 18 percent less sodium.

"Most of the salt in our diets comes from packaged food - food that may not even taste salty, such as bread," city Health Commissioner Dr. Thomas Farley noted in a release Monday.

Other health groups also have pressed the issue, and some companies have embarked on their own salt-reduction plans.

Sodium increases the risk of high blood pressure, a major cause of heart disease and stroke. Dietary guidelines recommend no more than 2,300 milligrams of sodium a day, but the CDC has found the average American consumes about 43 percent more than that.

There has been some scientific debate in recent years over how dangerous dietary salt is, and the Salt Institute, a trade association, has called New York City's salt reduction initiative misguided. The group didn't immediately respond to email inquiries Monday evening about the new ad campaign.

During Bloomberg's 11-year tenure, New York also has banned smoking in bars, restaurants, parks and beaches; banished trans fats from restaurant meals; compelled chain eateries to post calorie counts on menus, and tried to cap the size of non-diet sodas and other sugary drinks. A court struck down the beverage rule just before it was to take effect last month; the city is appealing.

Meanwhile, the city is working on a $250,000 social media and ad campaign to warn teens that they risk hearing loss from listening to personal music players at high volume.

• Read more articles by JENNIFER PELTZ

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