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First it was cholesterol, then saturated fat. Now trans fatty acids are the latest dietary demon. Like those nutrients, trans fats raise blood cholesterol levels and significantly increase the risk of premature heart disease.
Trans fat has been nicknamed "phantom fat" because the Food and Drug Administration does not require it to be listed on food labels.
As a result, even health-conscious consumers are often unaware that hundreds of popular foods-from margarine, baked crackers and biscuits to cookies, fish sticks and french fries-pack significant amounts of trans fatty acids.
Much of this fat comes from liquid vegetable oils that have been converted to solids because they stay fresh longer than conventional shortenings.
On average, Americans consume about five grams of trans fat per day, accounting for about 3 percent of their total calories, according to a 1999 study in the Journal of the American Dietetic Association.
While that may sound tiny, research has linked even small amounts of trans fat to an increased risk of heart disease.
A 1994 Harvard University study found more than twice the risk of heart attacks among those who ate partially hydrogenated oils, which are high in trans fat, compared with those who consumed little trans fat.
Several large studies in the United States and elsewhere, including the Nurses Health Study, also show a strong link between premature death and consumption of foods high in trans fatty acids.
Trans fats are unique in that they affect blood lipids in every way that is harmful. This hidden fat raises low-density lipoprotein (LDL) the harmful form of cholesterol ñ and lowers protective high-density lipoprotein (HDL) the so-called "good cholesterol." Most Americans are clueless about the dangers of trans fat.
A 1995 survey by the FDA found that 90 percent of those polled were either unaware of the risks of trans fat or mistakenly thought that it was beneficial. Even those who recognize trans fat as something to avoid are often confused about how best to do that.
Those who try to reduce trans fat will find it tough because most food labels don't have the information that you need to do that. Nutritional labels on prepared foods list the total grams of fat in products and that total does include trans fat, but there is no separate line showing, as they do with saturated fats, the actual amount of trans fats.
The FDA, however, proposed in November that food manufacturers begin including trans fat on labels. The 90-day public comment period won't end until mid-February and two food companies have already requested a 90-day extension. When the comment period ends, it could take about two years for any new rule to go into effect.
Under the proposed regulation, trans fat would be folded into the saturated fat gram count, since both raise the risk of heart disease. An asterisk would direct the consumers to the bottom of the label where they could find a reference listing the exact amount of trans fat included in the food.
If the proposal goes forward, trans fat would also be part of the nutritional information that the FDA considers when it gives foods such rankings as "lean," "extra lean," "reduced saturated fat" or "low saturated fat."
Low-cholesterol foods that now sometimes contain significant amounts of trans fatty acid would be required to contain less than two grams of saturated fat and trans fat per serving combined.
The FDA estimates that these labeling changes would prompt changes in eating habits that would save at least $1 billion in annual health care costs by preventing 6,400 cases of heart disease per year and at least 2,100 deaths.
Others say the benefits could be even greater. Trans fatty acids are responsible for about 30,000 premature deaths per year.
The Stealth Fat
Why the sudden concern about trans fats? Beef and high-fat dairy products have always contained minuscule amounts of trans fat, which is produced in the gastrointestinal lining of cattle. But in the 20th century, food manufacturers discovered the stability and long shelf life of trans fat.
During the past 50 years, trans fat has become one of the most common ingredients in both grocery store food and restaurant fare. Trans fats are produced when food manufacturers take liquid vegetable oils, heat them and add metal catalysts and hydrogen to the mix.
Called partial hydrogenation, this process produces hardened vegetable oils that remain solid at room temperature. They can then be made into shortening and margarine and are less likely to spoil.
With the proliferation of prepared foods in recent years, it's a small wonder that a long and varied list of products now contains hidden trans fat.
Food surveys suggest that the typical American eats about 34 grams a day of saturated and trans fat combined, well over the recommended daily intake of 20 grams of saturated fat for an average 2,000 calorie-a-day diet.
A close look shows clearly how the numbers creep up. Think that biscuit with three grams of saturated fat on the label isn't too bad? Add in the four grams of trans fatty acid and it jumps to seven grams of artery-clogging fat.
Peruse the label of those chocolate chip cookies that boast only two grams of saturated fat per serving. Surprise!
They contain double the amount of fat when the trans fat is taken into account. Ditto for the fish sticks, which tout just three grams of saturated fat per serving but actually pack another five grams of hidden trans fat.
Same goes for some of the most popular brands of baked crackers, which boast just one gram of saturated fat on their labels but contain an extra two grams of trans fat.
And that piece of apple pie? It has seven grams of saturated fat in the crust, but contains another seven grams of trans fat per serving.
In the dairy case, there's more confusion between butter and margarine. Butter contains no trans fatty acids. Each tablespoon of butter still has seven grams of saturated fat or roughly a third of the recommended daily intake.
Many margarines particularly stick margarines are low in saturated fat, providing just two to three grams per tablespoon, but they come loaded with trans fat, sometimes as much as three additional grams per tablespoon.
Stick margarines are almost as bad as butter, but the tub margarines are much better and the lower-fat tub margarines are much, much better.
Calculating Trans Fat In Your Food
Until a final rule is made, however, consumers can only guess how much trans fat most foods contain. The easiest way to check is usually to read the ingredient list. If partially hydrogenated oils or fats appear, the food has trans fat.
But knowing how much is difficult ñ unless the label happens to list monounsaturated and polyunsaturated fat grams, which are not required but are sometimes included on the label.
Even then, consumers need to calculate the amount of trans fat by adding grams of polyunsaturated, monounsaturated and saturated fat and subtracting that sum from the total fat listed on the label. The difference is a ballpark estimate of trans fat. For example, Oreos have seven grams of total fat in a serving.
The saturated fat, polyunsaturated and monounsaturated fat add up to five grams. The difference is two grams, and most of that is trans fat. Wheat Thins have six grams of total fat and only three grams are accounted for in the saturated, polyunsaturated and monounsaturated fat counts. That leaves three grams of fat and most of that is trans fat.
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