Trans-Fat: What Exactly is it, and Why is it so Dangerous?

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July 19, 2003 | 124,688 views

By Dr. Joseph Mercola
     with Rachael Droege

Trans fatty acids, also known as trans fat, is an artery-clogging fat that is formed when vegetable oils are hardened into margarine or shortening. It is found in many other foods besides margarine and shortening, however, including fried foods like french fries and fried chicken, doughnuts, cookies, pastries and crackers. In the United States, typical french fries have about 40 percent trans fatty acids and many popular cookies and crackers range from 30 percent to 50 percent trans fatty acids. Doughnuts have about 35 percent to 40 percent trans fatty acids.

Trans fat is known to increase blood levels of low density lipoprotein (LDL), or "bad" cholesterol, while lowering levels of high density lipoprotein (HDL), known as "good" cholesterol. It can also cause major clogging of arteries, type 2 diabetes and other serious health problems, and was found to increase the risk of heart disease. Many food companies use trans fat instead of oil because it reduces cost, extends storage life of products and can improve flavor and texture.

One problem with the use of trans fat is that food companies were not required to list it on nutrition labels so consumers had no way of knowing how much trans fat was in the food they were eating. Further, there is no upper safety limit recommended for the daily intake of trans fat. The Food and Drug Administration (FDA) has only said that "intake of trans fats should be as low as possible."

In a step in the right direction, the FDA has announced a final rule requiring food manufacturers to list trans fat on Nutrition Facts labels. The bad news is that the labels are not required until 2006 so consumers will need to fend for themselves when making food choices until that time.

While some foods like bakery items and fried foods are obvious sources of trans fat, other processed foods, such as cereals and waffles, can also contain trans fat. One tip to determine the amount of trans fat in a food is to read the ingredient label and look for shortening, hydrogenated or partially hydrogenated oil. The higher up on the list these ingredients appear, the more trans fat.

You can also add up the amount of fat in a product (saturated, monounsaturated and polyunsaturated), provided the amounts are listed, and compare the total with the total fat on the label. If they don't match up, the difference is likely trans fat, especially if partially hydrogenated oil is listed as one of the first ingredients.

A few companies, like Frito Lay, Lipton, and Nestle have already taken steps to eliminate trans fat in some products. Nestle is removing it from Rolo and Toffee Crisp and possibly other products. Their competitor, Cadbury, is also considering removing trans fats from some of its products.

Recently a lawsuit was filed against Nabisco, the Kraft Foods unit that makes Oreo cookies, seeking a ban on the sale of Oreo cookies because they contain trans fat, making them dangerous to eat. The case was later withdrawn because the lawyer who filed the suit said the publicity surrounding the case accomplished what he set out to do: create awareness about the dangers of trans fat. Kraft is also among the companies making efforts to reduce trans fatty acid in their products.

If you're wondering what foods are left that don't contain trans fat, don't worry, there are plenty! My book, Dr. Mercola's Total Health Program, contains plenty of recipes that are delicious and full of nutrition. You can also check out Know Your Fats: Complete Primer for Understanding the Nutrition of Fats, Oils and Cholesterol by Mary G. Enig, Ph.D., a nutritionist widely known for her research on the nutritional aspects of fats and oils, for more information about how trans fat--and other types of fat--can affect your health.

If you would like to comment on the trans fat issue I encourage you to post your thoughts by using the link at the top or bottom of this page. Comments will be posted on the Knowledge Filter postings so that everyone can get involved in the discussion.

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