If you’ve noticed that your favorite margarine seems oilier than it used to, there’s a reason: It’s been reformulated to avoid having to list trans fats on the label. As of Jan. 1, 2006, all food manufacturers are required to list the grams of trans fat per serving in a separate line directly under the saturated fat line on Nutrition Facts labels.
However, unlike total and saturated fat, the listing for trans fat doesn’t include a % DV (percent Daily Value) column. That’s because there is no recommended level of intake for trans fats, only to keep them as low as possible.
Trans fats are created when manufacturers add hydrogen to vegetable oils – a process called hydrogenation. The added hydrogen exerts a slight pull that rotates the fat chain, changing the configuration from what in chemistry is called "cis" to "trans" – thus, the name trans fats. The process is done to improve the texture, flavor stability and shelf life of foods containing these fats.
Unlike unaltered mono and polyunsaturated fats, which do not adversely affect blood cholesterol, trans fats act like saturated fats by raising LDL, or bad cholesterol. In addition, trans fats lower HDL, or good cholesterol, actually making them worse for the body than saturated fat. Trans fats also appear to boost blood triglyceride levels and impair the ability of blood vessels to dilate, both of which increase the risk for heart disease.
The FDA has required that saturated fat and dietary cholesterol be listed on food labels since 1993. By adding trans fat on the Nutrition Facts panel, consumers now know for the first time how much of all three – saturated fat, trans fat, and cholesterol – are in the foods they choose, so they are better able to make the heart-healthy food choices that can help them reduce their risk of heart disease.
Although a few foods, including beef, pork, lamb, butter and milk, naturally contain small amounts of trans fats, most of the trans fat in our diet comes from processed foods made with partially hydrogenated vegetable oils. Common sources of partially hydrogenated vegetable oils include stick and some tub margarines, shortening, cake and biscuit mixes, soup mixes, cakes, cookies, donuts, pastries, and fried snack foods such as crackers, potato chips and corn chips.
Many food manufacturers have been busy reformulating their products to eliminate as much of the trans fat in them as possible before the January labeling deadline. For many, the goal has been to get trans fat to under 0.5 grams (1/2 gram) per serving. At this level, they can round down to the coveted "0" listing. This is why you may see a few products that list 0 grams of trans fat on the label, but still include shortening or partially hydrogenated oil somewhere in the ingredient list.
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by Pat Kendall, Ph.D., R.D., Food Science and Human Nutrition Specialist, Colorado State University, Cooperative Extension