The population most likely to feel the sting of New York City’s recent trans fats ban: Kosher Keepers.

Trans fats were invented as a cheaper, more shelf-stable alternative to butter – they are plant oils with chemically added hydrogen to raise their melting point. Trans fats have become essential to those who keep kosher as many parve foods that substitute for a dairy counterpart use trans fat baddies such as margarine or Crisco.

Americans first swallowed trans fats in the 70s and 80s when corporate giants in the heartland rolled out a grand marketing blitz to pimp subsidized soy and corn to the masses. (This is the same era when high-fructose corn syrup replaced sugar throughout the land and an obesity crisis was born.)

In 2006 the jig is up: trans fats will kill you dead, they lead to heart disease faster than you can say “Parkay.”

Restaurants will still have until next July 1 to eliminate oils, margarines and shortening from recipes that contain more than a half-gram of trans fat per serving. By July 1, 2008, they would have to remove all menu items that exceed the new limit, including bread, cakes, chips and salad dressings.

It is likely that some trayf restaurants will look for an alternative cheap fat, many are already experimenting with lard.

For observant Jews, trans fat has become synonymous with dessert. Margarine and other partially hydrogenated oils are staple ingredients in most parve baked goods, and are practically indispensable in fleishig restaurants.

So what becomes of the babka when the trans fats are gone?