How Bad is Trans Fat in Food?

A food additive to avoid: partially hydrogenated vegetable oil, inter-esterified vegetable oil (trans fat)

Found in: Fat, oil, shortening: Stick margarine, crackers, fried restaurant foods, baked goods, icing, microwave popcorn.


Vegetable oil, usually a liquid, can be made into a semi-solid shortening by reacting it with hydrogen. Partial hydrogenation reduces the levels of polyunsaturated oils and also creates trans fats, which promote heart disease.

A committee of the U.S. Food and Drug Administration (FDA) concluded in 2004 that on a gram-for-gram basis, trans fat is even more harmful than saturated fat. Many food manufacturers have replaced hydrogenated shortening with less-harmful ingredients. The Institute of Medicine has advised consumers to consume as little trans fat as possible, ideally less than about 2 grams a day (that much might come from naturally occurring trans fat in beef and dairy products). Harvard School of Public Health researchers estimate that trans fat had been causing about 50,000 premature heart attack deaths annually, making partially hydrogenated oil one of the most harmful ingredients in the food supply.

Beginning in 2006, Nutrition Facts labels have had to list the amount of trans fat in a serving. That- and a threatened lawsuit against Kraft- spurred many companies, including Frito-Lay, Kraft, ConAgra, and others, to replace most or all of the partially hydrogenated oil in almost all their products. Usually the substitutes are healthier and the total of saturated plus trans fat is no higher than it was. Foods labeled “0g trans fat” are permitted to contain up to 0.5g per serving, while “no trans fat” means none at all. Consumers need to read labels carefully: foods labeled “0g trans” or “no trans” may still have large amounts of saturated fat.

Laws and lawsuits have gotten trans fat out of most restaurants, which had been using partially hydrogenated oil for frying chicken, potatoes, and fish, as well as in biscuits and other baked goods. New York City, California, and other jurisdictions strictly limited trans fat and got many restaurants to switch to healthier oils. Lawsuits against McDonald’s, KFC, and Burger King contributed to this progress.

In 2003, Denmark became the first country to virtually ban partially hydrogenated oil. In 2004, the Center for Science in the Public Interest petitioned the FDA to immediately require restaurants to disclose when they use partially hydrogenated oil and to begin the process of eliminating partially hydrogenated oil from the entire food supply. The FDA rejected the idea of requiring restaurants to disclose the presence of trans fat and in 2013 was continuing to consider CSPI’s petition to revoke the legal status of partially hydrogenated oil (the FDA con¬siders that oil to be “generally recognized as safe,” even though it and everyone else considers it to be “generally recognized as dangerous”). That would eliminate artificial trans fat from the American food supply. As it is, about 75 percent of the artificial trans fat has been eliminated, saving thousands of lives per year.

Fully hydrogenated vegetable oil does not have any trans fat, but it also does not have any polyunsaturated oils. It is sometimes mixed (physically or chemically) with polyunsaturated liquid soybean oil to create trans-free shortening. When it is chemically combined with liquid oil, the ingredient is called inter-esterified vegetable oil. Meanwhile, oil processors are trying to improve the hydrogenation process so that less trans fat forms.

Other relevant links:

• Check out this graphic about the breakdown of common cooking oils. See: What are Common Oils Made Up Of?

• These substitutions will help you cut unhealthy fat from your diet. See: Tips for Minimizing Saturated Fat Intake

• Are Americans improving their diets when it comes to fat consumption? See: Fats and Oils in the Changing American Diet

One Reply to “How Bad is Trans Fat in Food?”

Leave a Reply

Your email address will not be published. Required fields are marked *