Linda G. Hsieh is a practicing registered dietitian with over six years experience in clinical practice. Focusing on prenatal and pediatric nutrition, she has worked as a nutrition educator for over nine years.

Q: Why are partially hydrogenated fats bad for you? Should I limit them from my family's diet?

A: Many foods, such as crackers and margarine, contain partially hydrogenated oils. These types of fats are saturated and can increase the cholesterol in the blood. The main reason that they are used so often in foods is that they extend the shelf life of a product.

To lower the amount of this fat in your and your family's diet, get in the habit of reading foods labels and try to limit the foods that contain partially hydrogenated fats. Also, choose oils and margarine made from liquid oil. (The ingredients list will say "oil" instead of "partially hydrogenated oil".) Consider using olive oil (a heart healthy oil) on your bread instead of butter or margarine.

Even though some fats are considered unhealthy, fat is still an important part of a healthful eating plan. It provides energy, essential fatty acids, helps the body to absorb fat soluble vitamins and makes food taste good. Just be sure not to eat too much: Limiting fat intake to 30 percent of your overall calories is a sensible way for you and children over age 2 to eat. Restricting fat before age 2 isn't necessary.