What is trans fat?

Trans fats, also called trans fatty acids, are a type of fat formed when liquid vegetable oils go through a chemical process in which hydrogen is added to make the oils more solid. Food processors use trans fats because they allow longer shelf life and give food desirable taste, shape and texture. Most trans fat are found in shortenings, stick margarine, cookies, crackers, snack foods, fried foods (including fried fast food), doughnuts, pastries, baked goods and other processed foods made with or fried in oils that go through this process. Some trans fat is found naturally in small amounts in various meat and dairy products. Evidence suggests that consuming trans fat can raise LDL (“bad) cholesterol levels and lower HDL (“good”) cholesterol levels. 

Trans fats are another name for hydrogenated oils, which are oils produced artificially by inserting hydrogen molecules in vegetable oils. Products that contain trans fats can stay fresh longer without becoming stale, but the changed chemical structure of these fats gives them an unnatural shape that causes bodily cells to become malformed and malfunction. They are particularly bad for the heart because they damage the arteries, setting the stage for plaque to form. They also raise LDL, or “bad” cholesterol and lower HDL, or “good” cholesterol. Sources of trans fats include baked goods with high amounts of fat such as doughnuts, cakes, cookies, and croissants.

Trans-fatty acids are the most unhealthy fats of all. Not only do they raise low-density lipoprotein (LDL), but they also lower high-density lipoprotein (HDL -- "good" cholesterol). These fats appear to promote visceral fat, the deep belly fat that surrounds the organs, which can trigger heart disease and insulin resistance. Although trans fat exists in small quantities naturally in fatty meats and high-fat dairy foods, the major source is man-made partially hydrogenated vegetable oil, a solid fat that is used in some commercial baked goods and makes foods more shelf-stable.

Sources: Foods made with partially hydrogenated oil, including some cookies, cakes, crackers, pie crusts, and other baked goods, frozen foods, and margarine.

Trans fats are made in a process that changes liquid vegetable oils into solid fats. Trans fats are found in shortening, margarine, many packaged processed foods such as cakes, candies, cookies, snack foods such as crackers, and fried foods such as French fries. Read the food labels and choose foods that have 0 grams of trans fat. In the ingredient list, look for partially hydrogenated oil. Food can have up to 0.49 grams of trans fat and still list 0 grams on the label.

Trans fats are primarily created through hydrogenation, a process that turns liquid oils into solids like hard margarine and shortening. Some foods with trans fats include vegetable shortening, some margarines, crackers, cookies and many packaged snack foods. Some animal-based foods have small amounts of naturally occurring trans fats. Trans fats do not spoil as quickly as liquid fats, which makes them better in foods that are packaged for a long time. Trans fat can increase cholesterol levels the same way as saturated fat. The best way to check for trans fat in a food is to look at the list of ingredients. Food made with partially hydrogenated or hydrogenated oil will have trans fat. Be aware, though, that nutrition food labels will list trans fat only if there is more than 0.5 grams in a serving.

Trans fat is created when a liquid fat is infused with hydrogen and becomes solid at room temperature so it has a long shelf life. That's why you'll find it in processed food—everything from commercial baked goods, stick margarine, and shortening to fast food. These bad-guy fats increase triglycerides, total cholesterol, and harmful low-density lipoprotein (LDL) cholesterol, and decrease healthy high-density lipoprotein (HDL) cholesterol.

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Trans fat comes from the alteration of good unsaturated fat. This process involves adding hydrogen to the bonds in fatty acid chains, thereby saturating many of the previously unsaturated bonds. This factory-made fat became popular because it increased the shelf life of many food products. It is now mandatory for all food products to announce the presence of trans fat on their labels. If a food item has less than 0.5 g of trans fat per serving, the fat does not have to be disclosed and is labeled "0 gram," so it is always a good idea to look at the list of ingredients on a package to see whether partially hydrogenated vegetable oil is present.

The main determinant of whether fat is good or bad is how it affects your heart, particularly with regard to cholesterol. Polyunsaturated fats lower low-density lipoprotein (LDL), so these fats are considered good. Monounsaturated fats not only lower LDL but also raise high-density lipoprotein (HDL), and so they are considered even better. Olive oil, for example, is a monounsaturated fat. Saturated fats are bad because they raise LDL. Trans fat is even worse because not only does it raise LDL and lower HDL, it also makes platelets sticky!

Trans fats are extremely dangerous to the body chemistry. Trans fats are man-made fats that are used in processed foods. They are modified vegetable-derived fats that may be even worse than animal-derived saturated fats. They are also called hydrogenated oils, and they are laboratory-designed to have a similar chemical structure as saturated fat. They are solid at room temperature and have adverse health consequences. Like saturated fats, they promote heart disease and cancer.