Hydrogenated oils are oil products that are chemically altered to improve the oil's shelf life. There are two types of hydrogenated oils: fully hydrogenated and partially hydrogenated. The partially hydrogenated oils are terrible for heart health because they have high levels of trans fats. Fully hydrogenated oils complete the process of hydrogenation, which forms a single bond rather than a double bond, as in trans fats, and have lower trans fats as a result.
Fully Hydrogenated Shortening
Fully hydrogenated shortening is made in a similar manner to typical shortening options, but it completes the hydrogenation process to form only single bonds. It is much harder than regular shortening, which makes it difficult to spread and to use in cooking. Although it is harder to use, it has much less trans fat. Like any hydrogenated product, it is not healthy for the body or heart, but it is better than regular partially hydrogenated shortening.
Cottonseed oil, made from cotton, is one of the most unhealthy oil choices. It is commonly used in junk food items like potato chips because of the inexpensive price. According to the "Ask Dr. Sears" website, cottonseed oil is not only unhealthy because of the high levels of saturated fats, but also because it is sprayed heavily with pesticides and is often hydrogenated for longer shelf life.
Peanut oil is made from peanuts. It has a high level of saturated fats with a low level of unsaturated fats, which makes is ideal for cooking because it does not break down at high temperatures. Peanut oil is often hydrogenated to increase shelf life, but it does not break down as much as other types of oils during the hydrogenation process, so it results in lower trans fat content than other oils.
Hydrogenated Corn Oil
Corn oils are inexpensive oil options, but they are commonly hydrogenated to increase shelf life. Since corn oils are low in saturated fats and high in mono and poly unsaturated fats, the hydrogenation process breaks down the fats and result in high levels of trans fat. This is a very unhealthy oil choice when it is hydrogenated because of the high levels of trans fats that result from the hydrogenation process. When regular corn oil is used in high heat, it will hydrogenate because of the high temperatures.