The proposal to drastically restrict trans fats in New York City restaurants has been called a "great first step" by many diet experts, although several expressed caution about how the plan would work.
On Tuesday the New York City Department of Health and Mental Hygiene proposed a significant restriction on trans fats in foods served in restaurants, and also proposed that restaurants who already provide nutritional information also provide calorie amounts and make that information more accessible.
The restriction on trans fats requires that all foods served in restaurants contain no more than 0.5 grams of trans fats per serving. To put that into perspective, a single fast food meal can have more than 10 grams of fat. This restriction would take effect after 18 months.
Overall, experts agree that this is a great start.
"It is a very good action for the city to take," said Kelley Brownell, a professor of epidemiology and public health at Yale University. "This is one of the most significant nutrition advances I have seen in a long time."
Trans fats are an easy target because they lower good cholesterol (HDL) and raise bad cholesterol (LDL), which is a significant contributor to heart disease. Saturated fats do not affect good cholesterol. Another big difference between saturated and unsaturated fats is that saturated fats are natural, whereas trans fats are man-made.
"Trans fats have been widely studied, and all evidence points toward a greater risk of cardiovascular disease," said Mari-Pierre St-Onge, an assistant professor in the department of nutrition at the University of Alabama at Birmingham.
Experts are quick to point out that we consume much more saturated fat than trans fat. Trans Fats make up only about 2 to 4 percent of our daily diet, compared with 12 percent for saturated fats.
Safer alternatives to trans fats include monounsaturated and polyunsaturated fats, and the switch can be made. Denmark banned trans fats about two years ago, and officials said the transition to monounsaturated and polyunsaturated fats has been successful, with little effect on taste or cost.
But experts debate the number of people the trans fat restriction will actually save.
It is well established that trans fats are a major contributor to heart disease, but many other factors come into play too. It's estimated that up to 50,000 lives could be saved per year by restricting trans fats if the program were established nationwide.
With all the positive opinions about restricting trans fats, here are the areas for caution.
What will replace trans fats?
"It would be inappropriate to assume that restaurants will replace trans fats with more desirable mono- and polyunsaturated fats," said Laurie Tansman, at the department of clinical nutrition at Mount Sinai Hospital.
Many experts expressed concern that a change from trans fats may mean a switch to saturated fats.
"The final proposal will need to include a section that says that trans fats must not be replaced by saturated fats," said Tansman.
Another big worry is that changes in trans fat consumption still won't change the big picture.
"Any effort at improving public health will require a comprehensive approach, not just limiting trans fats," said Richard Fleming, with the Sierra Nevada VA Health Care System.