What is trans fat?
Trans fats are not formed by cooking, but only by a chemical process. Trans unsaturated fatty acids, or trans fats, are solid fats produced artificially by heating liquid vegetable oils in the presence of metal catalysts and hydrogen. This process, partial hydrogenation, causes carbon atoms to bond in a straight configuration and remain in a solid state at room temperature. Naturally-occurring unsaturated fatty acids have carbon atoms that line up in a bent shape, resulting in a liquid state at room temperature.
Which foods contain trans fatty acids?
Trans fats are produced commercially in large quantities to harden vegetable oils into shortening and margarine. Food manufacturers also use partial hydrogenation of vegetable oil to destroy some fatty acids, such as linolenic and linoleic acid, which tend to oxidize, causing fat to become rancid with time. The oils used to cook french fries and other fast food are usually this kind of partially hydrogenated oil, containing trans fats. Commercial baked goods frequently include trans fats to protect against spoilage. A small amount of trans fat also is produced in the gastrointestinal tract of cattle, so that low levels of these isomers are found in dairy and beef fat.
Are all fats the same?
Simply put: No. 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 you 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.
While unsaturated fats (monounsaturated and polyunsaturated) are beneficial when consumed in moderation, saturated and trans fats are not. It is advisable to choose foods low in saturated fat, trans fat, and cholesterol as part of a healthful diet.
Where can you find trans fat on the food label?
Food manufacturers have until Jan. 1, 2006, to list trans fat on the nutrition label. This phase-in period minimizes the need for multiple labeling changes, allows small businesses to use current label inventories and provides economic savings.
On July 9, 2003, the Food and Drug Administration published a final rule requiring manufacturers to list trans fatty acids, or trans fat, on the Nutrition Facts panel of conventional foods and some dietary supplements. With this rule, consumers will have additional information to make healthier food choices that could lower their intake of trans fat as part of a heart-healthy diet.
This final rule requires manufacturers of conventional foods and some dietary supplements to list trans fat on a separate line, immediately under saturated fat on the nutrition label. While scientific reports have confirmed the relationship between trans fat and an increased risk of coronary heart disease, none has provided a reference value for trans fat or any other information that FDA believes is sufficient to establish a Daily Reference Value, therefore a Daily Value will not be listed.
Dietary supplement manufacturers also must list trans fat on the Supplement Facts panel when their products contain reportable amounts (0.5 gram or more) of trans fat per serving. Examples of dietary supplements with trans fat are energy and nutrition bars.
FDA expects that, now that the final rule has been put forward, many food producers will begin providing trans fat information on the product label much sooner.
Until manufacturers are required to list the amount of trans fat, it is possible to determine the amount of trans fat by subtracting the grams of saturated, monounsaturated, and polyunsaturated fat from the total fat listed.
How can manufacturers reduce the trans fat levels in foods and still keep them solid?
There are several methods a manufacturer could use to lower the levels of trans fat and still keep it solid. They include:
- Mixing fully hydrogenated hard fats having no trans fat with nonhydrogenated oils.
- By using a process called interesterification. This process rearranges the molecular arrangement of the fat molecule to change the physical properties of the fat by combining nonhydrogenated oils with high saturated fat oils. An example is blending 20 parts fully hydrogenated soybean oil with 80 parts refined soybean oil. This mixture is then processed using interesterification. The result is soft tub margarine with a trace of trans fat.
- Using vegetable oils derived from plant biotechnology that are low in trans fat.
- Using gums or stabilizers to make the product solid.
- Using antioxidants to increase stability of the oil when made into a solid.
- Blending vegetable oils with partially hydrogenated fats to lower trans fat while keeping saturated fat low.
- A combination of some or all the above.