Confused about all the "fat" terminology? This week we'll look at the big picture and discuss trans-fatty acids; next week, we'll cover saturated and unsaturated fats.

We need fats in our diet to regulate metabolic processes, transport fat-soluble vitamins, and provide the fatty acids that are essential to life. However, too much fat is implicated in obesity, hypertension, and coronary artery disease.

Fats are composed of building blocks called "fatty acids." They are broken into saturated or unsaturated categories according to the number of hydrogen atoms in a molecule of fat.

Trans fats are created when unsaturated fatty acids are converted to saturated fatty acids; this happens when hydrogen atoms are added, a process called hydrogenation. This process is used to convert oils such as cottonseed, soybean, and sunflower oil to saturated fats that are more like animal fats in terms of texture and spreadability. You'll find trans fatty acids in cooking oils, margarine, shortening and processed foods such as French fries, fried chicken or fish, cakes, pies, pastries, muffins, crackers, and doughnuts, which are made with them.

Foods that are high in trans fatty acids are just as likely to cause increased total blood cholesterol and LDL (the "bad" cholesterol) levels as saturated fats. Therefore, it is recommended that you limit your intake of them. So far, trans fatty acids are not listed on food labels; FDA is in the process of adding that requirement. Look for "hydrogenated" in the labeling - that's a clue to trans fatty acids.

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