Trans Fatty Acid Overview
Trans fatty acids are one sub-type of fatty acid. Most people refer to trans fatty acids simply as trans fats. Trans fats help preserve the shelf life of food. To create a trans fat, manufacturers start with an unsaturated fatty acid and force hydrogen ions in it, under high pressure. This will "hydrogenate" the fatty acid. The goal of the hydrogenation is to create a saturated fatty acid, which is more stable and won’t go rancid. A byproduct of this reaction is a trans fatty acid.
Trans Fat Structure
In the image below you can see the difference between the structure of the various types of fatty acids. Trans and cis are essentially names for a different configuration. If you look under trans, at the bottom stick figure, you can see the straight line of the fatty acid. Look to the far right and you'll see what looks like the same structure, except the saturated fat does not have a double bond. The double bond is represented by the extra parallel line. What's interesting is that the cis and trans fatty acids actually have the exact same molecular structure, they have the same number of carbons, hydrogens and oxygen, in the same order. The only difference is that the orientation the molecule is pointing in relationship to the double bond. It's like it's flipped. This change is orientation creates a more stable molecule that won’t go rancid as easily as an unsaturated fat. Unsaturated fatty acids are less stable than saturated and trans fatty acids.
Health Effects of Trans Fats
Unfortunately, there are well defined detrimental effects to health associated with the consumption of trans fats. There is a very powerful association between consumption of trans fats and heart disease. There is no physiological need for the consumption of trans fats. Trans fats occur in nature only to a small degree (and these may in fact be healthy), but it's recommend to avoid manufactured trans fats. If a product has partially hydrogenated oil on the label, there is trans fat in the product. This also pertains to hydrogenated soybean oil. This is not a healthy fat. Manufacturers are now required to list the grams of trans fat on the label, but manufacturers can write 0 grams on the nutrition facts panel, even if there is 0.5 gram of trans fat. To figure out if a product has trans fat, look for partially hydrogenated and hydrogenated oil on the ingredient list.
The FDA announced June 16th, 2015 that manufacturers have 3 years to remove all partially hydrogenated oils from their products. They have determined that they are no longer GRAS (generally recognized as safe).
The FDA announced June 16th, 2015 that manufacturers have 3 years to remove all partially hydrogenated oils from their products. They have determined that they are no longer GRAS (generally recognized as safe).
Common Food Sources of Trans Fats
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There are naturally-occurring trans fats and artificial trans fats. Some foods such as milk, butter and meat contain naturally-occurring trans fats.
Most Americans consume artificial trans fats in processed food. As mentioned above, look for partially hydrogenated oil in the ingredient list to spot trans fats. Common foods with artificial trans fats include doughnuts, cakes, pie crusts, frozen foods such as pizza, cookies, crackers, stick margarines, peanut butter, dairy creamers, powdered sauces and dressings and powdered hot cocoa. |
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Processed Food Without Trans Fat is Still Processed
There are many products that claim to be trans fat free. Although this may sound positive, replacing trans fats with another fat substitution or food additive may not necessarily be healthier. If you are consuming a processed food, you are consuming a food with fewer nutrients and more food additives. It's recommended to consume whole food that is naturally free of trans fatty acids. Some foods have small amounts of naturally occurring trans fats and this is fine to consume.
References
- The FDA takes step to remove artificial trans fats in processed foods. U.S. Food and Drug Administration. June 15, 2016. Last accessed April 2, 2016. http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm451237.htm
- de Souza, R, et al. Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies. BMJ 2015;351:h3978. http://www.bmj.com/content/351/bmj.h3978
- Trans Fat. American Heart Association. Last updated October 7, 2015. Last accessed April 2nd, 2016. http://www.heart.org/HEARTORG/HealthyLiving/HealthyEating/Nutrition/Trans-Fats_UCM_301120_Article.jsp#.Vv_6LT80unQ
- Fatty acid image by Benjah-bmm27 from Wikipedia, CC0 1.0.
Last updated April 2, 2016