Hydrogenation changes liquid oil to solid. This is done by adding hydrogen. This process is done to make stick margarinesin sticks and spreads. That's why margarines in stick form have a lot of trans fats. Rule of thumb: Softer is better. Use healthier canola oil or olive oil for cooking when possible. Look for processed foods that have no hydrogenated oils. Choose a margarine that lists liquid vegetable oil as the first ingredient. It should have no more than 2 grams of saturated fat per serving.

Trans fats are in foods made with hydrogenated margarine and vegetable shortening. These include pastries and fried foods. Meat and dairy products have small amounts, too.

The best daily intake is none at all. Trans fats have no health benefits. You should eat a little as possible. Nutrition labels are required by the FDA to state if the food has any trans fats in it.

Although saturated fats can lead to heart attacks, trans fats are worse. They lower the level of HDL ("good") cholesterol in your body. The Academy of Nutrition and Dietetics advises using margarines that have no trans fat. Another choice is a diet margarine that has fewer trans fats.

Food labels must list the amount of trans fat per serving. They also must list the amount of saturated fat and cholesterol. Keep in mind that a food label can read "0 grams" of trans fat if each serving has less than 0.5 grams. Some foods have partially hydrogenated fats in them, but the small amount per serving means the label can say they have none.

Trans fats are in many processed foods.