Hydrogenated oil is a type of fat that food manufacturers use to keep foods fresher for longer. It is made by adding hydrogen to a liquid fat, such as vegetable oil, to turn it into a solid fat at room temperature. The process of hydrogenation creates trans fats, which are a type of unsaturated fat that can harm your health. Partially hydrogenated oils (PHOs) contain trans fats in the final product, which can affect heart health by increasing "bad" (low-density lipoprotein, or LDL) cholesterol and lowering "good" (high-density lipoprotein, or HDL) cholesterol. Fully hydrogenated oils, on the other hand, are mostly saturated fat and do not pose the same health risks as trans fat. Food manufacturers use hydrogenated oil as a preservative, to save money, extend shelf life, add texture, and increase stability. Hydrogenated oil is commonly found in ultra-processed foods that also have saturated fat, such as margarine, vegetable shortening, packaged snacks, and baked foods. Although fully hydrogenated oils are not banned and are considered safe, they are still saturated fats, and health experts recommend that people avoid foods that contain them and opt for fresh fruits, vegetables, whole grains, and lean proteins instead.