Back in 2008, the NYC Health Department fully implemented a ban on trans fat at all restaurants within the city limits (with the exception of foods served in the manufacturer's original packaging, such as crackers). The new rule has had a big impact on everyone (except Mayor Bloomberg, who got caught exploiting the loophole with trans fat Cheez-Its). New research shows the regulation had the desired effect, banishing a not-insignificant amount of trans fat from New Yorkers' hearts—and it's also had an impact nationwide.

Some big fast food chains like McDonald's responded to the new local rules by banning trans fat nationwide. And NYC's regulations were copied by over a dozen states and local governments. What's more, the city's trailblazing rules requiring restaurant chains to prominently display calorie counts is also going national—by the end of the year, the FDA is expected to finalize rules requiring restaurant chains around the country to post the calorie counts of their products right on the menu, thus ruining Uno Pizzeria's deep dish Farmer's Market pizza for everyone.

The NYC Health Department is not distributing copies of the study, which was conducted with the Annals of Internal Medicine. But the Associated Press obtained it, and reports thus:

Researchers surveyed customers and collected receipts for nearly 15,000 lunchtime purchases at fast-food chains around the city in 2007 and 2009, before and after the ban was in place. The amount of trans fat in each lunch sold dropped an average of 2.4 grams after the ban, researchers report in Tuesday's edition of Annals of Internal Medicine. The biggest drop, 3.8 grams, occurred in hamburger chains, followed by Mexican food and fried chicken chains.

Moreover, the study also suggests that restaurants didn't just swap out one bad ingredient for another as some nutritionists had feared. It found only a small increase in saturated fat, mostly in sandwich chains. That's at least partly due to those customers buying meals with a lot more calories in 2009 than before, said study co-author Christine Curtis. That time period saw Subway's introduction of $5 foot-long subs.

Trans fat is one of the leading causes of heart disease, and the American Heart Association recommends limiting trans fat to less than 2 grams a day. Americans' trans fat consumption has dropped by more than half over the last decade, due to public awareness campaigns, mandatory nutritional information, and restaurant regulations like the ones in NYC. However, the AP reports that 10 percent of children and adults consume more than 2.6 grams of industrially produced trans fats a day.

Christine Curtis, co-author of the study, tells us, "Our study found that after New York City’s restriction of trans fat, the average amount of trans fat in a fast food lunch went down, while saturated fat didn’t increase nearly as much. This is great news for New Yorkers: restaurant food has less trans fat and everyone benefits.”