Saturated versus unsaturated fats

We're demystifying fats today, and the first step is to understand the difference between the two main categories, saturated and unsaturated. The bad fats are saturated, meaning their molecular structure has no flexibility because all possible bonds are filled with hydrogen. Saturated fat is more likely to form plaques, clog arteries and raise blood cholesterol levels.

These fats are found naturally in meat and dairy foods and are more resistant to spoilage than their healthier counterparts, the unsaturated fats. These fats are either mono-unsaturated or poly-unsaturated, meaning their molecular structure has one or more bond where hydrogen is absent. These fats are less stable, easier to metabolize, and seem to lower blood cholesterol levels. Because these fats have such a volatile structure, they can easily go rancid when oxygen attaches to the open bonds.

To avoid spoilage, food manufacturers hydrogenize these good fats by adding hydrogen and turning them into the more shelf-life friendly saturated fats, also called trans fatty acids, which are much less heart-friendly. Nutrition labels won't list trans fatty acids as such, but if you remember to look for foods low in saturated fats and avoid hydrogenated or partially hydrogenated fats, you'll be doing your heart a big favor.

Resources

For more detailed information on trans fatty acids, visit the American Heart Association Web site.