Please note: This information was current at the time of publication. But medical information is always changing, and some information given here may be out of date. For regularly updated information on a variety of health topics, please visit, the AAFP patient education website.

Information from Your Family Doctor

Trans Fats


Am Fam Physician. 2009 Aug 15;80(4):372.

  See related article on trans fats.

What are trans fats?

Trans fats are a type of fatty acid. Fatty acids are a source of energy for your body. Fatty acids come from fruit and vegetable oils, seeds, nuts, animal fats, and fish oils. Not all fatty acids are unhealthy, but some, such as trans fats, can be bad for you. Trans fats are often used in processed foods and baked goods because they are cheaper than animal fats, have a wide range of textures, and have a longer shelf life.

What types of foods contain trans fats?

Margarines, shortening, crackers, cookies, chips, salad dressings, and fried foods may be made with trans fats. Many foods from fast food restaurants also have high levels of trans fats.

Why are they unhealthy?

Trans fats may increase the levels of bad cholesterol in your body and decrease the levels of good cholesterol. Studies have found that eating more trans fats is linked to a higher risk of heart disease.

How do I avoid them?

You should add more fruits and vegetables to your diet in place of some packaged foods. Fruits and vegetables are naturally free of trans fats. You should also read food labels carefully. Many foods now say “ trans fat free” on the package.

Food labels must list trans fats, total fat, saturated fat, and cholesterol. Trans fats may also be listed on food labels as hydrogenated (hi-DRAW-je-nate-ed) or partially hydrogenated vegetable oils. Some fast food restaurants do not use trans fats anymore, but it is important to ask before you order. The American Heart Association recommends that no more than 1 percent of your total calories per day come from trans fats. This equals about 2 to 2.5 grams per day.

Where can I get more information?

Your doctor

American Academy of Family Physicians

Web site:

American Heart Association

Web site:

Fast Food Facts

Web site:

This handout is provided to you by your family doctor and the American Academy of Family Physicians. Other health-related information is available from the AAFP online at

This information provides a general overview and may not apply to everyone. Talk to your family doctor to find out if this information applies to you and to get more information on this subject.


Copyright © 2009 by the American Academy of Family Physicians.
This content is owned by the AAFP. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. This material may not otherwise be downloaded, copied, printed, stored, transmitted or reproduced in any medium, whether now known or later invented, except as authorized in writing by the AAFP. Contact for copyright questions and/or permission requests.

Want to use this article elsewhere? Get Permissions

More in AFP

Editor's Collections


Sep 15, 2020

Access the latest issue of American Family Physician

Read the Issue

Email Alerts

Don't miss a single issue. Sign up for the free AFP email table of contents.

Sign Up Now

Navigate this Article