Trans fats are formed when hydrogen is added to liquid oils, turning them into solid fat like shortening or margarine. Hydrogenation increases shelf life of foods, adds flavor and texture, and can be useful in preparation. Hydrogenated fat has been sold in the U.S. for over 100 years (beginning with Crisco shortening, in 1911).

In the 1990s, studies showed that trans fats were a cause of coronary artery disease. Trans fats not only increase "bad" cholesterol, but also decrease good cholesterol. A 1994 article in the American Journal of Public Health claimed trans fats were the cause of 20,000 deaths in the U.S. Increased awareness of the effects of trans fats led to mandatory labeling of food products in 2006.

Trans fat consumption is a concern to food manufacturers. Many manufacturers have taken steps to remove trans fat (also known as "partially hydrogenated oils") from their products. McDonald's restaurants stopped cooking french fries in trans fats over 10 years ago.

What are the alternatives to trans fat or hydrogenated oils? One answer is to use butter instead - in very small amounts! Other types of oils such as canola, soy bean and "tropical" oils (palm, palm kernel, coconut) can be substituted. But for dieters, the best solution is to avoid fatty foods altogether!

When buying food for yourself or your family, always read the label! Trans fats may be listed as "partially hydrogenated oil." Keep in mind that foods containing less than half a gram of trans fats can state on their label they contain zero! Eating many servings of those foods will add up.

To learn more about healthy eating, read our nutritionist Elaine Murphy's blog, and join CalMWM for our regular nutrition live chats.