Shortening, like margarine, is a fat that is solid at room temperature. Also like margarine, it was traditionally made with hydrogenated oils linked to inflammation. Some brands have reduced the amount of trans fats used in production to a level that permits the label “zero trans fats.” But this label is permitted so long as the amount of trans fats is below 0.5 grams. The shortening you buy with this label may still have trace amounts of trans fats. A better way to ensure you’re steering clear of these harmful compounds? Read the ingredients list. If trans fats are present, the hydrogenated or partially hydrogenated oil will be listed on the label.