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Understanding trans fat

Trans fat can be harmful to your heart and arteries. Avoiding it helps protect your health.

In the same way that some things you eat offer health benefits with nearly no drawbacks (think fresh fruits), other items offer drawbacks with no benefits (think trans fat).

Though some types of fat can help your body absorb vitamins and ensure healthy growth, trans fat has nothing to offer but health troubles, such as high cholesterol and an increased risk of heart disease.

Knowing what trans fat does, where it's found and how to avoid it can help you and your heart stay in good health.

Good fat gone bad

Though small amounts of trans fat naturally occur in some animal products, it's created in much larger amounts by a process called hydrogenation. Hydrogenation means adding hydrogen to vegetable oil. This transforms the oil into a solid fat. Partially hydrogenating oils produces trans fat. Fully hydrogenated oils have almost none.

Though trans fat increases a food's shelf life and makes it taste better for a longer time, it can also wreak havoc on your health.

Unlike the vegetable oil it's made from, which may have some health benefits in its original form, trans fat isn't needed by the body and has no known health benefits, according to the U.S. Department of Agriculture (USDA).

What's worse, trans fat increases levels of low-density lipoproteins (LDL, or bad cholesterol) and decreases levels of high-density lipoproteins (HDL, or good cholesterol). Both changes can increase your risk of heart disease.

Because of the possible risks from trans fat and the lack of benefits, the USDA recommends eating as little of it as possible.

Where's the fat?

The U.S. Food and Drug Administration (FDA) requires manufacturers to list the amount of trans fat on nutrition fact labels. However, be aware that a food can have up to 0.5 grams of trans fat per serving and still claim to have "0 grams trans fat."

Much of the trans fat eaten by Americans is artificial and comes from partially hydrogenated vegetable oils used in commercial foods, such as baked goods, frozen pizza, coffee creamer, french fries, shortening and stick margarine, according to FDA.

FDA no longer considers partially hydrogenated oils to be safe for human use. As of June 2018, FDA no longer allows manufacturers to add the ingredient to their products.  

Small amounts of trans fat occur naturally in meat and dairy products. And some edible oils have a very low level of trans fat. These foods can be part of a healthy diet.

Shopping smart

Read labels. The American Heart Association offers these suggestions:

  • For cooking, use naturally occurring oils that aren't hydrogenated whenever you can. Olive and canola oil are good examples.
  • Choose processed foods made with unhydrogenated oil. 
  • Limit red meat, and go for low-fat dairy products. 

Reviewed 5/2/2022

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