Trans-fatty acids are an example of what can happen to essential nutrients when a food is processed. Also called hydrogenated fats, these fatty acids are found in margarine, vegetable shortenings, crackers, cookies, snack foods and numerous other processed foods. Trans-fats are produced by a chemical process in which hydrogens are added to an unsaturated fatty acid. The food industry uses this process because it converts a liquid fat to a soft solid form, like margarine, and also because it increases the shelf-life for fats. In this process, however, the fatty acid molecule shifts structures to a structure that is not found in the body; that is, the fats in the body occur in what is called a "cis" 3-dimensional structure, and trans-fatty acids are the opposite of that, and are a "trans" structure. Chemically, they are different.