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Trans Fat

N. Jay Sorensen, MBA RD
Last Updated: February 16, 2015

Q: What is trans fat?

A: Trans fat (also know as trans fatty acids) is a specific type of fat formed when liquid oils are made into solid fats like shortening and hard margarine. However, a small amount of trans fat is found naturally primarily in some animal-based foods.

Q: Where will I find trans fat?

Nutrition Facts

A: Vegetable shortenings, some margarines, crackers, cookies, snack foods, and other foods made with or fried in partially hydrogenated oils.

Trans fat behaves like saturated fat by raising low-density lipoprotein (LDL or “bad”) cholesterol that increases your risk of coronary heart disease (SHD). Trans fat can be found in some of the same foods as saturated fat, such as vegetable shortenings, some margarines, crackers, candies, cookies, snack foods, fried foods, baked goods, and other processed foods made with partially hydrogenated vegetable oils.

Trans fat is made when hydrogen is added to vegetable oil – a process called hydrogenation. Hydrogenation increases the shelf life and flavor stability of foods containing these fats. Usually the hydrogen atoms at a double bond are positioned on the same side of the carbon chain. However, partial hydrogenation reconfigures some double bonds and the hydrogen atoms end up on different sides of the chain. This type of configuration is called “trans” (means “across” in Latin). The structure of a trans unsaturated chemical bond looks like the diagram below.

Trans Fat (i.e., trans fatty acids)

Trans Fat

Hydrogen atoms are on opposites sides of the chain of carbon atoms at the carbon-carbon double bond.

Q: Is it possible for a food product to list the amount of trans fat as 0 g on the Nutrition Facts panel if the ingredient list indicates that is contains “partially hydrogenated vegetable oil?”

A: Yes. Food manufacturers are allowed to list amounts of trans fat with less than 0.5 gram (1/2 g) as 0 (zero) on the Nutrition Facts panel. As a result, consumers may see a few products that list 0 gram trans fat on the label, while the ingredient list will have “shortening” or “partially hydrogenated vegetable oil” on it. This means the food contains very small amounts (less than 0.5 g) of trans fat per serving.