The process of making trans fats, called hydrogenation, was invented in 1809. Increased demands for butter and lard forced scientists to look for fat alternatives. By pumping hydrogen gas into oil, liquid fats at room temperature become more like solids.

This was extremely beneficial for food companies, because trans fats have a longer shelf life than butter and lard. Hydrogenated and partially hydrogenated oils found their way into almost every processed and packaged food in the grocery stores. Margarine spreads and vegetable shortenings were touted as healthier alternatives.

In the 1990s, scientists discovered that trans fats raise bad cholesterol (LDL) and lower good cholesterol (HDL). A high LDL cholesterol level in combination with a low HDL cholesterol level significantly increases risks of heart disease, a leading killer of men and women. In 2006, the Food and Drug Administration required all food manufactures to include trans fats on food labels.

Because food companies have yet to find fat alternatives at similar costs, partially hydrogenated and hydrogenated oils are still used as ingredients in food products. If a product is made with hydrogenated oils but contains less than 0.5 grams of trans fat per serving, the product can be labeled as "no trans fats." However, eating several servings of "no trans fats" processed foods per day could result in total trans fat consumption at an unhealthy level.

Trans fats are mostly found in processed foods such as cookies, chips, crackers, cakes, margarine, shortening and fast food. The best way to avoid trans fats completely is to read the ingredients list rather than the nutrition facts panel and look for partially hydrogenated or hydrogenated oil -- your heart will thank you.