This is the VOA Special English Health Report.

New York City wants to fight fat. The Board of Health has passed a ban ontrans fatsin all restaurants.

Eating places have until July to stop frying foods in oils high in trans-fatty acids. And they have until July of 2008 to reduce trans fat in other foods to less than one-half gram per serving.

Trans fats are often called partially hydrogenated fats. They form when hydrogen is added to liquid oils and fats to make them solid. Trans fats make foods last longer.

But they increase the level of low-densitylipoprotein, known as bad cholesterol, in the blood. High levels of LDL can increase the risk for heart disease.

The use of trans fats expanded because of worries about saturated fats. Saturated fat also raises bad cholesterol. So is one fat worse than the other?

James Cleeman is coordinator of the cholesterol education program at the National Institutes of Health. Doctor Cleeman says gram for gram, both raise LDL levels about the same. But he points out that American adults on average get more than four times as much saturated fat in their diet as trans fat.

Trans fats, though, also lower the level of HDL, high-density lipoprotein -- so-called good cholesterol. Saturated fats do not.

Doctor Cleeman says lower levels of good cholesterol have been linked to increased risk for heart disease in the population as a whole. But for an individual, he says, lowering good cholesterol by eating trans fat has not been shown to increase the risk.

Other cities may also ban trans fats. A measure proposed in Chicago has been awaiting further action.

The New York Board of Health also wants menus in fast-food places to now list the number of calories in foods. The idea is to help people make wiser choices.

Public health officials say two out of three Americans are overweight.

But the National Restaurant Association calls the actions in New York misguided social engineering. And it says the ban raises serious legal concerns.

The group notes that many restaurants have recently announced they are moving away from using trans fat. And it says without much time to change, many will have no choice but to use oils high in saturated fats.

Some people see the ban as an attack on freedom of choice. They say food inspectors should worry more about dangers like E. coli bacteria.

And that's the VOA Special English Health Report, written by Jill Moss. I'm Shirley Griffith.

tras fat: 反式脂肪酸

lipoprotein : 脂蛋白