A study published in the Journal of the American Dietetic BP Optimizer Review Association found that most American's know they need to avoid trans fats, but only 20% actually knew which foods contained trans fats.
Trans fatty acids are a processed fat, produced as a by-product when hydrogen is added to make a substance more solid at room temperature. For example, margarine is hydrogenated vegetable oil – hydrogen was added and the by-product trans fat is produced. Although, it should be noted that many margarine's have changed production procedures so the trans fatty acid by-product is not produced. Trans fatty acids are just as bad for heart health (if not worse) than saturated fats. The fats increase LDL (bad) cholesterol levels and lower HDL (“good”) cholesterol.
Trans fats, also known as hydrogenated oils, are artificially produced in the laboratory by adding extra hydrogen atoms to unsaturated vegetable oils. They have long been a favorite of the food industry for their increased shelf life over conventional oils. Unlike natural fats, however, these fats have no nutritional value and drastically increase the risk of cardiovascular disease and death. Like saturated fats, they increase the body's levels of LDL (“bad”) cholesterol, but unlike those fats they also lower its levels of HDL (“good”) cholesterol.