What are trans Fatty Acids?

1. trans fatty acids are hydrogenated forms of poly- and mono- unsaturated fatty acids--i.e., the configuration of the double bond(s) in the fatty acids are modified to the trans position.
   
   
2. Hydrogenation was developed in the 1930's at a time when lard was the major fat available for commercial purposes.  To make vegetable oil a suitable substitute for lard, hydrogenation was developed to give vegetable oil consistency and "hardness" that extended the shelf life.Thus, stick margarine has traditionally contained more trans fatty acids than tub margarine.
   
   
3. The concern with trans fats has been that they raise LDL cholesterol levels when substituted for the parent vegetable oil. However, trans fats lower LDL cholesterol when substituted for lard, butter and other animal fats rich in saturated fatty acids.  Therefore, trans fats have better effects on LDL cholesterol than traditional shortenings of lard, butter, and palm oil.  Hence, patients should choose margarine over butter.  Tub margarine is preferable to stick margarine.  Most tub margarines currently available contain minimal amounts of trans and many now meet criteria allowing them to be labeled as "no trans" products.     
    
4. Other sources of trans fats are meats and dairy products.
   
   
5. Even though there has been a perception that trans fatty acid intake is of major significance, Americans eat 4-10 times more saturated fat than they do trans fat.  Thus, reducing saturated fat intake will reduce trans intake and should be the major focus of a cholesterol-lowering diet.