According to the American Heart Association, you should limit consumption of hydrogenated fats, also known as trans fats, to less than 1 percent of total daily calories because, like saturated fats, they raise blood cholesterol levels, especially LDL, or "bad" cholesterol levels. One major source of hydrogenated oils in the American diet is fast foods. Partially hydrogenated vegetable oils provide about 75 percent of the trans fatty acid consumption in the U.S. diet.
Identification
Trans fats are formed when cooking oils are hydrogenated. The word "hydrogenate" means to add hydrogen. When unsaturated fatty acids from vegetable oils are hydrogenated, through the use of heat, hydrogen or certain metal catalysts, a structural change occurs. The oil becomes harder, more resistant to rancidity and more saturated at room temperature.
Applications
The hydrogenation of liquid oils, or turning liquid oil into a solid, allows for wider uses and easier transportation due to an increased shelf life. Hydrogenated oils are also less expensive than animal fats. These are a few of the characteristics that make hydrogenated oils attractive to the food industry. According to the Harvard School of Public Health, when saturated fat was identified as a major contributor to high cholesterol, fast food restaurants switched from using beef tallow for frying French fries and donuts to using partially hydrogenated vegetable oils which, at the time, seemed to be a smart change.
Content
Before 2006, the use of hydrogenated oils and the trans fatty acid content of many popular fast foods, such as fried chicken, pastries and French fries were quite high. The U.S. Department of Agriculture's National Nutrition Database reports that trans fatty acid content among fast foods varies greatly. Donuts, French fries, fast food pastries, such as pies and cinnamon rolls, and chicken tenders are some of the worst offenders, providing 2 to 6 g trans fats per serving.
Decreased Use
An article featured in Science Daily in July 2010 noted that fast food restaurants, such as McDonald's, Burger King and Wendy's, significantly decreased the trans fatty acid composition of their French fries between 1997 and 2008 by modifying their use of hydrogenated oils. This is primarily due to the connection between hydrogenated oils, which yield trans fats, and elevated cholesterol levels.
Recommendations
Organizations such as the U.S. Department of Agriculture and the American Heart Association recommend limiting trans fat intake to less than 1 percent of total calories. Thus, on a 2,000-calorie diet, that would amount to 2 g or less of trans fats. If you consume fast foods, even moderately, it is very likely that you exceed that limit. Even considering the changes that have occurred in recent years in the fast food industry, with a decreased use of hydrogenated oils, the trans fat content of many fast foods continues to be higher than may be healthy.
References
- American Heart Association: Know Your Fats
- Harvard School of Public Health: Shining the Spot Light on Trans Fats
- Science Daily: Fast Food Chains Have Significantly Decreased Trans Fats in Cooking Oils, Study Finds
- U.S. Department of Agriculture National Nutrition Database: Fatty Acid Content of Selected Foods
Member Comments