What are trans fatty acids?

Trans unsaturated fatty acids, or trans fats, are solid fats produced artificially by heating liquid vegetable oils in the presence of metal catalysts and hydrogen.¹ This process, partial hydrogenation, causes carbon atoms to bond in a straight configuration and remain in a solid state at room temperature. Naturally-occurring unsaturated fatty acids have carbon atoms that line up in a bent shape, resulting in a liquid state at room temperature.

Which foods contain trans fatty acids?

Trans fats are produced commercially in large quantities to harden vegetable oils into shortening and margarine. Food manufacturers also use partial hydrogenation of vegetable oil to destroy some fatty acids, such as linolenic and linoleic acid, which tend to oxidize, causing fat to become rancid with time. The oils used to cook french fries and other fast food are usually this kind of partially hydrogenated oil, containing trans fats. Commercial baked goods frequently include trans fats to protect against spoilage. A small amount of trans fat is also produced in the gastrointestinal tract of cattle, so that low levels of these isomers are found in dairy and beef fat

Metabolic studies have shown that trans fats have adverse effects on blood lipid levels--increasing LDL ("bad") cholesterol while decreasing HDL ("good") cholesterol. This combined effect on the ratio of LDL to HDL cholesterol is double that of saturated fatty acids.³

Trans fats have also been associated with an increased risk of coronary heart disease in epidemiologic studies.⁴

Based on the available metabolic studies, we estimated in a 1994 report that approximately 30,000 premature coronary heart disease deaths annually could be attributable to consumption of trans fatty acids.⁴

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Waist Circumference Predicts Heart Disease Risk

The findings are based on an analysis of data from 10,969 subjects who participated in the third National Health and Nutrition Examination Survey from 1998 to 1994.

Dr. Shankuan Zhu, from the Medical College of Wisconsin in Milwaukee, and colleagues found that waist circumference was more strongly tied to cholesterol levels, blood pressure, and blood glucose levels than was BMI.

"The present study reports waist circumference cutoffs that correspond to well-established BMI cutoffs, recommended by the World Health Organization (news - web sites) and the National Institutes of Health (news - web sites) for overweight and obesity, in their association with cardiovascular disease risk factors," the researchers conclude.

"Our findings indicate that waist circumference is a better indicator of cardiovascular disease risk than is BMI across three race-ethnicity groups."

SOURCE: American Journal of Clinical Nutrition, February 2005.

People of all ages can benefit from physical activity. Try to exercise at least three to four times a week for about 30 minutes each day. If you have a busy schedule, you can break up those 30 minutes into three 10-minute sessions – it is the total time that you exercise per day that counts. You can choose from a wide range of activities, including brisk walking, cycling, dancing and swimming. We know that even moderate, daily activity, such as gardening, mowing the lawn or taking the stairs instead of the lift, can help your heart. If you have not exercised recently, be sure to check with your doctor before starting any exercise programme.