A new study has shown that trans fatty acids are associated with increases in triglycerides and a drop in HDL, the "good" cholesterol. A group of 26 volunteers rotated through 5-week diets in which they received fat from either soybean oil, semi-liquid margarine, tub margarine, shortening, stick margarine, or butter. All diets had 30% of total calories from fat.

At the AHA convention, researchers reported that, as the trans fatty acids increased in the diet, and the polyunsaturated fats decreased, the triglyceride levels 4 hours after a meal increased. Overall, those on the stick margarine diet had triglyceride levels 18% higher than those using semi-liquid margarine. Stick margarine also caused a drop in HDL, the "good" cholesterol. While butter increased HDL, it also caused a significant increase in LDL, the "bad" cholesterol.

Blood cholesterol contains a variety of components - some good, some bad. [See table.] LDL cholesterol and triglycerides are thought to increase the risk of heart disease, while HDL helps clear cholesterol from the body.

We'll provide more information on the various types of fats in the next couple of weeks.

Type of Fat	Effect on Cholesterol Levels
Trans fatty acids	Reduce the "good" cholesterol, HDL Increase triglycerides
Saturated fats	Increase total blood cholesterol Increase the "bad" cholesterol, LDL
Polyunsaturated fats	Reduce total cholesterol Reduce the "good" cholesterol, HDL
Monounsaturated fats	Lower LDL; no effect on HDL

Related information About it: Cholesterol - In your blood, in your diet | Diet