Trans Fat 101 - what and where?
Written by Gloria Tsang, RD
Published in Feb 2004; updated in Feb 2006
 Trans fat is found in numerous foods - commercially packaged goods, commercially fried food such as French Fries from some fast food chains, other packaged snacks such as microwaved popcorn as well as in vegetable shortening and some margarine. Indeed, any packaged goods that contains "partially-hydrogenated vegetable oils", "hydrogenated vegetable oils" or "shortening" most likely contain trans fat.
Before the invention of trans fatty acids, we cooked food with lard, palm oil or butter etc which are high in saturated fat. Researchers found that saturated fat increases LDL cholesterol (the Bad cholesterol) which may increase the risk of heart disease.
Therefore, manufacturers started to use the healthier vegetable oils in their food production. As liquid vegetable oils are not stable to heat and can go rancid easily, scientists began to "hydrogenate" liquid oils so that they can withstand better in food production process and provide a better shelf life. As a result of hydrogenation, trans fatty acids are formed.
Similar to saturated fatty acids, trans fatty acids also increase LDL cholesterol (the Bad cholesterol) and lower HDL cholesterol (the Good cholesterol) therefore increasing the risk of heart disease. Some studies also showed that a diet high in trans fatty acids may be linked to a greater risk of Type 2 Diabetes.
What about "Fully-Hydrogenated" oil?
Fully hydrogenated oil does not contain trans fatty acids. Instead, it contains more saturated fat (primarily stearic acid). Stearic acid is immediately converted into oleic acid (a type of mono-unsaturated fatty acids) in our body and that's why stearic acid does not raise LDL cholesterol (the bad cholesterol).
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 Key:
Minimize the intake of both saturated fat and trans fat by checking the food labels. Effective January 1, 2006, all packaged food products must list trans fats content on the Nutrition Facts panel. The amount of trans fats per serving of food will appear under the Total Fat section of the label.
For those labels not listed the amount of trans fatty acids in countries where trans-fat labeling law does not exist, here is how you can figure it out on your own: add up the values for saturated, polyunsaturated and monounsaturated fats. If the number is less than the "Total fats" shown on the label, the unaccounted is trans fat.
Please note that trans fats are also found in many fried foods such as chicken nuggets and french fries from the fast food chains as they often use vegetable oil containing trans fats. Despite some chains have started changing their frying oil, it is advised to eat less fat anyway - less total fat in general means less trans and saturated fats!!!
Update: In April 2004, the FDA Food Advisory Committee voted in favor of recommending that trans fatty acid intake level be reduced to "less than 1% of energy (2g per day of a 2000 kcal diet)".
Corporate food manufacturers such as Kraft and Kellogg have announced their plans to replace certain vegetable oils in their production to reduce or eliminate trans fatty acid content.
In Canada, Health Canada and the Heart and Stroke Foundation of Canada are currently co-chairing a task force aimed at finding ways to effectively reduce industrial trans fatty acids in the food supply to the lowest levels possible.
What about the naturally occurring Trans Fat? Trans fat naturally found in animal products is generally the good kind of trans fat. For more information, read A Good Trans Fat - Conjugated Linoleic Acid.
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