Food companies began use hydrogenated oil to help increase shelf life and save costs. Hydrogenation is a process in which a liquid unsaturated fat (e.g. olive or peanut oil) is turned into a solid fat by adding hydrogen. During this processing, a type of fat called trans fat is made.
While small amounts of trans fats are found naturally in some foods, most trans fats in the diet come from these processed hydrogenated fats.
Partially hydrogenated oils can affect heart health because they increase “bad” cholesterol and lower “good” cholesterol. On the other hand, a fully hydrogenated oil contains very little trans fat, mostly saturated fat, and doesn’t carry the same health risks as trans fat.
Still, food manufacturers continue to use partially hydrogenated oils to save money, extend shelf life, add texture and increase stability.