What Does Zero Trans Fat Really Mean?

Health Professional

A reader recently asked how can a food list 0 grams of trans fat on the Nutrition Facts panel and still have partially hydrogenated vegetable oil listed in the ingredients. Are they not the same?  


The answer is yes: trans fat is the same as partially hydrogenated vegetable oil. Trans fats are made by adding hydrogen atoms to vegetable oil through a process called hydrogenation. The "trans" refers to the positioning of these hydrogen atoms on different sides of the carbon atom backbone. "Partially" hydrogenated refers to the fact that the carbon backbone of the vegetable oil is not fully saturated with hydrogen atoms. If it was fully saturated with hydrogen atoms, then it might be called saturated fat depending on the chemical bonds of the carbon atoms.

Why do companies do this? By changing the chemical structure of vegetable oil to a partially hydrogenated one, the flavor and shelf life of this oil or fat is improved. That's why so many flavorful products such as cookies and chips can sit on a gas station stand for months at a time without losing their flavor and form.

The downside is that trans fat is very bad for your cholesterol levels. (See my blog from July 26, 2006 entitled: Trans fatty acids: What's the Worry?) It raises bad LDL levels and lowers good HDL levels. High intake of trans fat has been associated with an increase risk of heart attack.


Why then can a food have trans fat yet still list 0 grams of content on its food label? To answer that, we only need to look as far as the federal government, for only could the federal government come up with such a logical rule.

On July 11, 2003, the Food and Drug Administration ruled that by January 1, 2006, the amount of trans fat in a serving of food must be listed on a separate line under the total fat section on the Nutrition Facts panel. There are several scenarios in which a food may contain trans fat and yet the amount may be reported as 0 grams or not even listed at all in this Nutrition Facts panel.

  • The food per serving contains less than 0.5 grams of total fat (all fat combined). The manufacturer is not required to report total fat content let alone its % breakdown. A footnote should appear stating that the food is "not a significant source of trans fat."
  • The food per serving contains more than 0.5 grams of total fat and thus total fat is listed with its % breakdown of saturated and unsaturated fat. But, the amount of trans fat per serving is less than 0.5 grams. The label may then read 0 grams of trans fat. (You do the math?) The ingredients label, however, must list partially hydrogenated vegetable oil or "shortening" if there is still some trans fat in the food.
  • The food product was already in distribution prior to January 1, 2006, and therefore was not required to have trans fat listed separately in the Nutrition Facts panel.
  • The food product was distributed after January 1, 2006, but the manufacturer received an extension allowing it to utilize pre-existing Nutrition Facts labels that do not list trans fat. The manufacturer has to apply for this extension, and it must be approved by the FDA.

Just a few final comments about trans fat and the Nutrition Facts panel. If the food contains some trans fat, albeit a very small amount, it should appear in the ingredients as partially hydrogenated vegetable oil or shortening. When trans fat is listed on the Nutrition Facts panel, you won't see a % daily value listed with it. That's because there is no recommended amount of trans fat in a daily diet since trans fat in general is bad for you. So, it's not recommended that you eat it.

However, eliminating all trans fat from your diet is impractical and extremely difficult since many foods that contain trans fat also contain essential nutrients.