Nutrition Column – Trans Fat: KeepitAs Low as Possible

Add trans fats to the list of fats you need to watch out for on food labels. By Jan. 1, 2006, all food manufacturers will be required to include a new line on their Nutrition Facts labels listing grams of trans fat per serving. The trans fat information will be directly below the saturated fat information. Some manufacturers have already begun listing trans fat on labels; others are busily trying to modify formulations in an effort to minimize the amount of trans fat they’ll need to report on their product labels. What’s the scoop on trans fat?

What are trans fats and why are they added to food? Trans fats are made 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.

Why are trans fats bad? Unlike unaltered mono and polyunsaturated fats, which do not adversely affect blood cholesterol, trans fats act like saturated fats by raising LDL ("bad") cholesterol. In addition, trans fats lower HDL ("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. Research is underway to determine how much trans fat is too much. Until then, the current recommendation is "to keep trans fatty acid consumption as low as possible."

Trans fats in the Diet.  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.

Until next January when trans fats must be listed on all food labels, the only way to determine if a product contains trans fats is to read the list of ingredients. If the list includes the words "shortening," "partially hydrogenated vegetable oil" or "hydrogenated vegetable oil," the food contains trans fat. The higher the word is on the ingredient list, the greater proportion of trans fat contained in the product.

Even without trans fat labeling, you can estimate the amount of trans fat in a product from the Nutrition Facts label. Just note the amount of total fat, then add up the grams listed next to each individual fat. If the product lists hydrogenated oil in its list of ingredients, the missing grams are mostly trans fat.

Margarine vs. Butter.  Always up for debate is whether choosing butter or margarine is healthier. Although margarines tend to contain more trans fat than butter, the total amount of trans and saturated fat found in most margarines is less than that found in butter. In addition to containing a large amount of saturated fat, butter also contains cholesterol. Therefore, most researchers still prefer margarines, particularly soft tub margarines in which liquid oils are the first ingredient.

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by Pat Kendall, Ph.D., R.D., Food Science and Human Nutrition Specialist, Colorado State University, Cooperative Extension