What is trans fat?

Most trans fat is made through a process that adds hydrogen to vegetable oil. This causes the oil to become solid at room temperature.

This partially hydrogenated oil isn't costly to make, and it has a long shelf life. Some restaurants use partially hydrogenated vegetable oil in their deep fryers. That's because it doesn't have to be changed as often as do other oils. Some areas in North America and Europe have passed laws to limit or ban the use of trans fat in restaurants and other businesses that prepare or serve food.

Some meat and dairy products have a small amount of natural trans fat. Natural trans fat also can be bad for health.