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What is Trans Fat?


When you look at the Nutrition Facts box on any food label you will find the item Trans Fat.  And hopefully the food item you are looking at doesn’t have any.  So what is Trans Fat and why is it bad for me?

Simply put, trans fat is shortening.  Liquid vegetable oils are chemically changed into solid shortening by a process known as hydrogenation.  This process fundamentally alters the properties of the fat.  Its new solid nature has a much longer shelf life than the original liquid oil.  This means that any product made with hydrogenated or partially hydrogenated fats such as crackers, cookies, pastries, margarine and a whole range of other foods prepared with shortening have a much longer shelf life before going rancid.  

This breakthrough in food technology was originally viewed as a very good thing because now we could have a healthy alternative in baked goods without using butter or lard which is a source of saturated fat and cholesterol.   And the longer shelf life improved our food distribution system.  So from the 1950’s through the 1980’s hydrogenated fats were used in an increasingly wide range of prepared food items.  And shortening “made from 100% vegetable oil” became a household staple.

Life was great until it was discovered that this new trans fat was highly correlated to a higher incidence of heart disease.  Liquid oils generally are unsaturated while solid fats like cheese, butter and the marbling fat in meat are saturated.  When we chemically change liquid oils to solid shortening, we create a highly saturated fat.  As we all know, saturated fat raises our bad (LDL) cholesterol and lowers our good (HDL) cholesterol which in turn clogs our blood vessels.  And as it turns out, trans fat is worse for us than naturally occurring saturated fat.  In fact the scientific evidence was so compelling that in 2006 the FDA mandated that trans fat be added to all food labels so that consumers could make informed choices affecting their health.  And that brings us back to looking at a Nutrition Facts food label.

The good news is that food manufacturers have removed much of the trans fat from their products.  But remember to read the fine print.  There are still products out there with the health claim of “No Trans Fat” displayed prominently on the front of the package.  Double check the ingredient label.  If you find partially hydrogenated vegetable oil, then the product has trans fat in it.  By law, if a product has less than half a gram of trans fat in a serving, the producer can legally claim zero trans fat.   

It’s still less expensive to buy shortening than vegetable oil.  So many of the fried foods in restaurants will be deep fried in trans fat.  This gives us yet another reason to limit fried food consumption.  One little step at a time is how we improve our diet.  Keep moving and watch out for trans fat.

Tim Scallon is a registered dietitian and Director of Clinical Nutrition and the HC Polk Education Center at Memorial Health System in Lufkin.  The Polk Center provides individual and group education on diabetes, heart disease and stroke; monthly classes on healthy cooking; and monthly support groups in Lufkin and Livingston.  In cooperation with Sodexo Food Service and the City of Lufkin, the Polk Center produces the nationally viewed TV series Memorial Cooking Innovations where dietitian Tim Scallon teams up with Chef Mani Marini to demonstrate how healthy eating can taste great.  The show can be seen on cable in 46 cities and on the Memorial web site at http://www.memorialhealth.org. Call 639-7585 for more information.

By Tim Scallon, M.S. R.D. L.D.
Director of the Horace C.  Polk Jr. Regional Diabetes Center and 
Department of Clinical Nutrition at Memorial Health System of East Texas

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