Experts say that trans fat is the worst type of fat to eat. That's because it raises "bad" cholesterol and lowers "good" cholesterol. A diet high in trans fat raises the risk of heart attack and stroke. Sometimes this type of fat also is called trans-fatty acids.

In some countries, government agencies have taken action to reduce or remove trans fat from the food supply. In the United States, the Food and Drug Administration, also called FDA, has banned food makers from adding the major source of trans fats to foods and drinks.

The FDA expects that its move will prevent thousands of heart attacks and deaths every year. But many countries around the world haven't yet taken action to curb trans fats.

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.

Trans fat from partially hydrogenated oil may be found in in food products such as:

• Commercial baked goods such as cakes, cookies and pies.
• Shortening.
• Packaged foods such as microwave popcorn.
• Frozen pizza.
• Refrigerated dough, such as biscuits and rolls.
• Fried foods, including french fries, doughnuts and fried chicken.
• Nondairy coffee creamer.
• Stick margarine and other spreads.

Trans fat raises the risk of heart attacks and stroke. Trans fat also has a bad effect on cholesterol levels.

There are two main types of cholesterol:

• Low-density lipoprotein (LDL) cholesterol. LDL cholesterol is known as "bad" cholesterol. It can build up in the walls of arteries and make them hard and narrow.
• High-density lipoprotein (HDL) cholesterol. HDL cholesterol is known as "good" cholesterol. It picks up extra cholesterol and takes it back to the liver. The liver breaks down cholesterol and passes it out of the body.

Trans fat raises LDL cholesterol and lowers HDL cholesterol. This can make a heart attack or stroke more likely.

In the United States, a food label can show 0 grams of trans fat if a food has less than 0.5 grams of trans fat in a serving.

Products made before the FDA ban of added trans fat might still be for sale. So check to see if a food's ingredient list says partially hydrogenated oil. If it does, that means the food has some trans fat in it, even if the amount is below 0.5 grams.

These hidden trans fats can add up quickly. That's especially true if you eat many servings of foods that have less than 0.5 grams a serving.

Try to limit foods with trans fat as much as possible. Trans fat is not part of a healthy diet.

Foods free of trans fats aren't always healthy. Food makers might use other ingredients that aren't good for you. Some of these ingredients have a lot of saturated fat that can raise cholesterol. Examples include coconut, palm kernel and palm oils.

In a typical healthy diet, about 20% to 35% of total daily calories can come from fat. Try to keep saturated fat at less than 10% of total daily calories. So if you eat about 2,000 calories a day, limit yourself to 120 calories or less from saturated fat.

Unsaturated fat is a healthier option than is saturated fat. Good sources of unsaturated fat include:

• Olive, peanut, soy, sunflower, safflower and canola oils.
• Avocado.
• Pecans, almonds, walnuts and other nuts.
• Fatty fish.

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.

Trans fat from partially hydrogenated oil may be found in in food products such as:

• Commercial baked goods such as cakes, cookies and pies.
• Shortening.
• Packaged foods such as microwave popcorn.
• Frozen pizza.
• Refrigerated dough, such as biscuits and rolls.
• Fried foods, including french fries, doughnuts and fried chicken.
• Nondairy coffee creamer.
• Stick margarine and other spreads.

Trans fat raises the risk of heart attacks and stroke. Trans fat also has a bad effect on cholesterol levels.

There are two main types of cholesterol:

• Low-density lipoprotein (LDL) cholesterol. LDL cholesterol is known as "bad" cholesterol. It can build up in the walls of arteries and make them hard and narrow.
• High-density lipoprotein (HDL) cholesterol. HDL cholesterol is known as "good" cholesterol. It picks up extra cholesterol and takes it back to the liver. The liver breaks down cholesterol and passes it out of the body.

Trans fat raises LDL cholesterol and lowers HDL cholesterol. This can make a heart attack or stroke more likely.

Most trans fats are formed through an industrial process that adds hydrogen to vegetable oil, which causes the oil to become solid at room temperature.

This partially hydrogenated oil is inexpensive and less likely to spoil, so foods made with it have a longer shelf life. Some restaurants use partially hydrogenated vegetable oil in their deep fryers, because it doesn't have to be changed as often as do other oils.

Some meat and dairy products have a small amount of naturally occurring trans fats. However, it's not clear how these trans fats affect health.