Just the facts. From the experts.

In early November, the Food and Drug Administration began the process (a preliminary determination) of banning artificial trans fats from our food. If the determination is finalized, trans fats will not be allowed as an ingredient in foods without FDA approval. So what are trans fats and what could it mean if they are banned?

The American Heart Association says, “Trans fats (or trans fatty acids) are created in an industrial process that adds hydrogen to liquid vegetable oils to make them more solid.” They are used because they are easy to handle, inexpensive to produce, they have a great shelf life and they create a great taste and texture as a food ingredient.

We wanted to learn more, so we contacted sports nutritionist Dr. Liz Applegate and food scientist and registered dietitian Dr. Ruth MacDonald.

Dr. Liz ApplegateSenior Lecturer, Department of Nutrition and Director of Sports Nutrition, Intercollegiate Athletics, University of California – Davis


Dr. Ruth MacDonaldChair and Professor of the Department of Food Science & Human Nutrition, Iowa State University.


First of all, what do you think about the proposal to ban trans fats?

Dr. Applegate: I think it’s a good move by the FDA. I hope it’s something consumers will embrace, along with the idea that to improve heart health, they have to watch their total fat intake, exercise and maintain a healthy body weight.

Why did food companies create trans fats?

Dr. MacDonald: Trans fats were actually an unintended consequence of the hydrogenation process. Hydrogenated fats were created to be more healthful because unsaturated fats pose less risk to health than saturated fats, that is, assuming you are concerned about heart disease. For some other illnesses, such as cancer, unsaturated fats may promote that disease. Until recently, there was no data to indicate trans fats were harmful.

What are the benefits of trans fats? Without them, what happens? Will food still taste the same after the trans fat ban?

Dr. MacDonald: The major problem with unsaturated fats is that they become oxidized when exposed to air – this causes off flavors and colors. The process of hydrogenation stabilizes these fats from the oxidative effects. In essence, food stays fresher longer. The characteristics of foods may also be affected by changing the fat source – and food companies will need to work hard to find replacement fats and oils that still generate the same taste, texture and shelf-life that they have with hydrogenated fats. This will undoubtedly increase the cost of foods due to the investment needed in research and product development and the change in ingredient supply.

How do food companies make trans fats?

Dr. Applegate: Food manufacturers take an inexpensive oil like soybean oil or cottonseed oil and make it more stable and solid at room temperature by hydrogenating it. It affects the texture of what the food manufacturers are making. For example, if you have a cookie or a cracker that needs to be crumbly instead of oily and have a good mouth feel, you would use a hydrogenated oil that contains solid fat. It’s too expensive to use butter. During World War II, the U.S. rationed food and other goods. Many times, butter was sent to the armed forces, which left food manufacturers without butter as an ingredient. They used hydrogenation of vegetable oil to create an inexpensive substitute for butter.

What is hydrogenation?

Dr. Applegate: Imagine using a liquid fat ingredient, like soybean oil, in a cookie or a cracker. The oil would literally drip out of it. Food manufacturers created an inexpensive food fat with similar properties to butter, but less expensive than butter. Hydrogenation is changing the liquid fat of an oil into a solid fat like butter. Vegetable shortening is an example. Hydrogenation adds atoms of hydrogen to make a liquid fat into a solid fat (trans fat). Partially-hydrogenated means that when manufacturers add the hydrogen atom, some of the oil becomes saturated fat, while small amounts are left as trans fat. Hydrogenation also helps with stability. Liquid fats or oils are not stable for long periods of time and can go rancid, with an off-taste.

What is partially-hydrogenated oil?

Dr. MacDonald: A fatty acid with a lot of double bonds is called unsaturated (carbons are ‘unsaturated’ with hydrogens). Oils, which are liquid at room temperature, are comprised of mainly unsaturated bonds. Solid fats, such as butter and lard, have fewer unsaturated fats and more saturated fats. To make oils more solid at room temperature, techniques are used to hydrogenate (add hydrogens) back to the fatty acids. This process produces margarine or shortenings from vegetable oils. The amount of hydrogenation can be controlled so that you can generate a fat that has the characteristics needed for a food product – hence ‘partially-hydrogenated’.

If this new ruling from the FDA is finalized, how quickly will foods with artificial trans fat products be eliminated?

Dr. Applegate: It’s going to be a few years. Food manufacturers will need time to reformulate their products.

Overall, what’s your healthy eating advice?

Dr. MacDonald: The best advice is to consume foods in moderation and to select low fat foods whenever possible.

Can I use hydrogenation to make my own trans fat oil in my kitchen?

Dr. Applegate: Not really. Hydrogenation is a chemical reaction. To hydrogenate soybean oil, you would need hydrogen gas and a chemical catalyst to start the reaction. This is best left up to food manufacturers and food chemists.  



What should we ask our experts about?

Add a Comment

Craving more food facts? Read on!

Trans Fats Moving Off the Menu
Troubled about Trans Fats?
Trans Fat Take-Aways: The Trans Fats Webcast Highlights