Trans fat worse for heart than saturated fat

By Suzanne Rostler

NEW YORK, Jul 12 (Reuters Health) - When choosing between a thick juicy steak and a heaping plate of French fries, the meat just might be the healthier option, a study from the Netherlands suggests.

The study measured the effect of trans fat, found in fried foods and processed foods such as cookies, crackers and pastries, and of saturated fat, found in meat, butter and some dairy products, on blood vessel function and cholesterol levels.

Researchers fed 29 healthy, nonsmoking adults two different diets. The "Trans-diet" contained 9.2% of total calories from trans fat and the "Sat-diet" diet contained the same proportion of calories from saturated fat. Individuals followed the diets for 4 weeks, and then switched to the other diet for 4 weeks.

Dr. Nicole M. de Roos, of Wageningen University, and her colleagues studied participants' blood vessel function by measuring how readily the vessels dilated in response to blood flow. Relatively poor dilation is a marker of heart disease risk.

According to the results, the trans-fat diet reduced this blood vessel function by 29% and lowered HDL ("good")-cholesterol levels by about one fifth, compared with the saturated-fat diet. Previous research has shown that trans fats, like saturated fats, also raise LDL ("bad")-cholesterol levels.

"This suggests that trans fatty acids increase the risk of heart disease more than the intake of saturated fats," the researchers conclude.

In an interview with Reuters Health, de Roos said that companies manufacturing foods such as doughnuts and cookies should report how much trans fat is found in the item on the label. Additionally, restaurants could use liquid vegetable oils, which do not contain much trans fat, rather than solid "hydrogenated" fats to fry foods. Hydrogenated fats are oils that undergo a process to make them solid at room temperature.

"The major sources of trans fats in our diet are the ready-made baked goods and fried fast foods," de Roos explained. "These foods are not labeled, so the consumer does not know how much trans fat he gets."

Trans fat accounts for 4% to 7% of dietary fat intake in the US and The Netherlands, according to the report in the July issue of Atherosclerosis, Thrombosis and Vascular Biology: Journal of the American Heart Association.

To reduce the amount of trans fats in the diet, the American Heart Association recommends that consumers cook with unhydrogenated oils such as canola or olive oil and choose processed foods made with these oils rather than with hydrogenated or saturated fat.

Low-fat margarine, a minor source of trans fat, should be used instead of butter, which contains both trans and saturated fats. Liquid or tub margarines are preferable to stick varieties.

SOURCE: Atherosclerosis, Thrombosis and Vascular Biology 2001;21:00-00.

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