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Fat, Trans Fatty Acid (Trans Fat), and Cholesterol
Q: What are fats and fatty acids?
A: Fats are a group of chemical compounds that contain fatty acids. Energy is stored in the body mostly in the form of fat. Fat is also needed in the diet to supply essential fatty acids that are substances essential for growth but not produced by the body itself. The terms fat and fatty acids are frequently used interchangeably.
Q: What are the main types of fatty acids?
A: There are three main types of fatty acids: saturated, monounsaturated and polyunsaturated. All fatty acids are chains of carbon atoms with hydrogen atoms attached to the carbon atoms. A saturated fatty acid has the maximum possible number of hydrogen atoms attached to every carbon atom. It is therefore said to be "saturated" with hydrogen atoms, and all of the carbons are attached to each other with single bonds.
In some fatty acids, a pair of hydrogen atoms in the middle of a chain is missing, creating a gap that leaves two carbon atoms connected by a double bond rather than a single bond. Because the chain has fewer hydrogen atoms, it is said to be "unsaturated." A fatty acid with one double bond is called "monounsaturated" because it has one gap. Fatty acids having more than one gap are called "polyunsaturated."
The fat in foods contains a mixture of saturated, monounsaturated and polyunsaturated fatty acids. In foods of animal origin, a large proportion of fatty acids are saturated. In contrast, in foods of plant origin and some seafood, a large proportion of the fatty acids are monounsaturated and polyunsaturated. The structure of saturated and unsaturated chemical bonds looks like the diagram below.
Saturated Fat
(i.e., saturated fatty acid)
Unsaturated Fat
(i.e., unsaturated fatty acid)
Q: What is trans fat?
A: Trans fat (also known as trans fatty acids) is a specific type of fat formed when liquid oils are made into solid fats like shortening and hard margarine. However, a small amount of trans fat is found naturally, primarily in some animal-based foods.
Q: Where will I find trans fat?
A
Vegetable shortenings, some margarines, crackers cookies, snack foods, and other foods made with or fried in partially hydrogenated oils.
Trans fat behaves like saturated fat by raising low-density lipoprotein (LDL or "bad") cholesterol that increases your risk of coronary heart disease (CHD). Trans fat can be found in some of the same foods as saturated fat, such as vegetable shortenings, some margarines, crackers, candies, cookies, snack foods, fried foods, baked goods, and other processed foods made with partially hydrogenated vegetable oils.
Trans fat is made when hydrogen is added to vegetable oil -- a process called hydrogenation. Hydrogenation increases the shelf life and flavor stability of foods containing these fats. Usually the hydrogen atoms at a double bond are positioned on the same side of the carbon chain. However, partial hydrogenation reconfigures some double bonds and the hydrogen atoms end up on different sides of the chain. This type of configuration is called "trans" (means "across" in Latin).
Q: What is the role of fat in the diet?
A: Fat is a major source of energy for the body and aids in the absorption of vitamins A, D, E, and K, and carotenoids. Both animal and plant-derived food products contain fat, and when eaten in moderation, fat is important for proper growth, development, and maintenance of good health. As a food ingredient, fat provides taste, consistency, and stability and helps us feel full. In addition, parents should be aware that fats are an especially important source of calories and nutrients for infants and toddlers (up to 2 years of age), who have the highest energy needs per unit of body weight of any age group.
Q: Are all fats the same?
A: Simply put: no. While unsaturated fats (monounsaturated and polyunsaturated) are beneficial when consumed in moderation, saturated fat and trans fat are not. Saturated fat and trans fat raise LDL ("bad") cholesterol. Therefore, it is advisable to choose foods low in both saturated and trans fats as part of a healthful diet.
Q: What about cholesterol?
A: Cholesterol is a waxy substance that occurs naturally in the tissues of all animals. The human body needs cholesterol to function properly, such as producing vitamin D, bile acids to digest fat, and many hormones. Given the capability of all tissues to synthesize sufficient amounts of cholesterol for their needs, there is no evidence for a biologic requirement for dietary cholesterol. Scientific evidence indicates a positive linear trend between cholesterol intake and LDL-cholesterol levels, and therefore, an increased risk of CHD.
Section 2 - Foods that Contain Trans Fat, Saturated Fat, and Cholesterol
Q: What is the daily trans fat intake of Americans?
A: FDA estimates that the average daily intake of trans fat in the U.S. population is about 5.8 grams or 2.6% of calories per day for individuals 20 years of age and older. On average, Americans consume approximately 4 to 5 times as much saturated fat as trans fat in their diet.
Trans fat can be found in vegetable shortenings, some margarines, crackers, candies, cookies, snack foods, fried foods, baked goods, and other processed foods made with partially hydrogenated vegetable oils. Small amounts of naturally occurring trans fat can be found in some animal products, such as butter, milk products, cheese, beef, and lamb.
Estimates of the average trans fat intake of U.S. adults from food groups (e.g., cakes, cookies, shortening, etc.) are described in the economic analysis for FDA's final trans fatty acid labeling rule, Trans Fatty Acids in Nutrition Labeling, Nutrient Content Claims, and Health Claims published July 11, 2003 (68 FR 41434 at 41468-41470). FDA based its estimates on USDA's 1994-96 Continuing Survey of Food Intakes by Individuals and on the special 1995 USDA database of trans fat content of selected foods.
Q : What foods contain saturated fat, trans fat, and cholesterol?
A: Saturated and trans fats can be found in some of the same foods, such as vegetable shortenings, some margarines (especially margarines that are harder), crackers, candies, cookies, snack foods, fried foods, baked goods, and other processed foods made with partially hydrogenated vegetable oils. High amounts of saturated fat are found in animal products, such as beef and pork, chicken skin, butter, whole milk, and cheese. Foods high in cholesterol include liver, other organs meats, egg yolks, and dairy fats.
It is important to choose foods with the lower combined amount of saturated fat and trans fat and the lower amount of cholesterol.
Q: Should trans fat be eliminated from the diet?
A: No. According to experts, eliminating trans fat completely from the diet would require such extraordinary dietary changes (e.g., elimination of foods, such as dairy products and meats that contain trans fatty acids) that eliminating trans fat could cause an inadequate intake of some nutrients and create health risks.
Q: What actions can consumers take to lower their intake of saturated fat, trans fat, and cholesterol?
A: Here are some actions you can take every day to keep your consumption of both saturated and trans fats and cholesterol low while consuming a nutritionally adequate diet.
Check the Nutrition Facts panel to compare foods because the serving sizes are generally consistent in similar types of foods. Choose foods lower in saturated fat, trans fat, and cholesterol. For saturated fat and cholesterol, use the Quick Guide to %DV: 5%DV or less is low and 20%DV or more is high. (Remember, there is no %DV for trans fat.)
Choose Alternative Fats. Replace saturated and trans fats in your diet with mono- and polyunsaturated fats. These fats do not raise LDL (or "bad") cholesterol levels and have health benefits when eaten in moderation. Sources of monounsaturated fats include olive and canola oils. Sources of polyunsaturated fats include soybean, corn, sunflower oils, and foods like nuts.
Choose vegetable oils (except coconut and palm kernel oils) and soft margarines (liquid, tub, or spray) more often because the combined amount of saturated and trans fats is lower than the amount in solid shortenings, hard margarines, and animal fats, including butter.
Consider Fish. Most fish are lower in saturated fat than meat. Some fish, such as mackerel, sardines, and salmon, contain omega-3 fatty acids that are being studied to determine if they offer protection against heart disease.
Limit foods high in cholesterol such as liver and other organ meats, egg yolks, and full-fat dairy products, like whole milk.
Choose foods low in saturated fat such as fat free or 1% dairy products, lean meats, fish, skinless poultry, whole grain foods, and fruit and vegetables.
Q: Do dietary supplements contain trans fat?
A: Yes, some dietary supplements contain ingredients that also include partially hydrogenated vegetable oil or trans fat as well as saturated fat and cholesterol. As a result of FDA's new label requirement, if a dietary supplement contains a reportable amount of trans fat, which is 0.5 gram or more, dietary supplement manufacturers must list the amounts on the Supplement Facts panel. Examples of dietary supplements that may contain saturated fat, trans fat, and cholesterol include energy and nutrition bars.
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