As the body of knowledge about the effects of fat grows, so does the confusion over the terminology. Last week we defined trans fats and talked about where they are found in food. This week we'll differentiate between saturated and unsaturated fats.

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.

• Saturated fatty acids are used in the process of manufacturing cholesterol in your body. Too much of these will raise total blood cholesterol and LDL (the "bad" cholesterol). They occur mainly in animal products, including meat, butter, cream, whole milk, and cheese. Some vegetable oils - particularly coconut and palm kernel oil - are high in saturated fat.
• Polyunsaturated fatty acids may lower total blood cholesterol but they also decrease HDL (the "good" cholesterol). They are found in corn, cottonseed, safflower, sesame, soybean, and sunflower cooking oils.
• Monounsaturated fatty acids may lower LDL without affecting the levels of HDL. They are found in vegetable oils such as olive, peanut, and canola oils, and in foods such as olives, peanut butter, avocados, and nuts including peanuts, cashews, pecans, walnuts, almonds, and pistachios.

Thus, unsaturated fats are better for you than saturated fats. And monounsaturated fatty acids are the least likely to cause problems with cholesterol levels. See recommended intakes of the different fats in the table.

Summary of National Cholesterol Education Program Guidelines for Fats

Type of Fat		Recommendation
Saturated fat		Less than 10% of total daily caloric intake Lower for people with severely high blood cholesterol levels
Polyunsaturated fat		10% or less of total daily caloric intake
Monounsaturated fat		Up to 15% of total daily caloric intake
Trans fats		Limit intake AHA recommends 10% or less of total calories from saturated fats and trans fatty acids

Related information About it: Cholesterol - In your blood, in your diet | Diet