Trans Fats:Devil in Disguise

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The term “trans fats” is short for “trans fatty acids,” which in turn refers to the biochemical composition of a particular kind of fat. Biochemically speaking, trans fatty acids are unsaturated fatty acids that have at least one double bond in what is known as the “trans configuration.” More importantly, in relation to obesity, trans fats are produced by the food industry during the partial hydrogenation of vegetable oils.

This partial hydrogenation is a process that converts vegetable oils into semisolid fats that can then be used in manufacturing, commercial cooking, and margarine production. The food industry has found partially hydrogenated oils to be attractive due to their ability to extend product shelf life, their stability for deep-frying, and their semisolid nature, which allows for flavor and palatability enhancement of baked goods. Due to this, trans fats can be found in pastries such as doughnuts, cinnamon rolls, and pie crusts--ever wonder how a pie crust can last for a year on the shelf? They can also be found in biscuits, crackers, cookies, pizza crusts, premade dough, deep-fried foods, certain popcorns, and many, many other food products.

Under current regulations, as much as 0.49 g of trans fat per serving can be added to foods without having to be listed in the “trans fat” portion of the nutrition label.

Therefore, consumers must look for the words “partially hydrogenated” in the ingredients list—this tells you that trans fats are, indeed, present in the food product in question. However, the Food and Drug Administration (FDA) announced on June 16, 2015 that it will move forward with a campaign to ban all partially hydrogenated fats as unsafe in any amount.

Why Are Trans Fats Bad for You?

According to a wealth of research, trans fats are linked to a number of related maladies, including obesity, diabetes, cardiovascular disease, and sudden death from cardiac causes. Trans fats have even been found to cause molecular changes at the level of the fat cell, or adipocyte, itself. Specifically, trans fats can cause the adipocytes to release more free fatty acids into the bloodstream, which then can go on to cause atherosclerosis and plaque formation in the coronary arteries, for example.

Trans fats can also cause adipocytes to display greater inflammatory responses, contributing to overall inflammation within the body, another factor that has been linked to a variety of diseases, including cardiovascular disease and diabetes. Trans fats also increase inflammation through the action of monocytes or macrophages, which are white blood cells that are part of the body’s natural immune system. Another way to think of this: trans fats cause our body’s immune system to respond as if it were under an attack, producing inflammation in response to this perceived attack.

Trans fats also act detrimentally at the level of the liver cell, or hepatocyte. Via this unfavorable impact on the hepatocyte, they cause an increase in LDL cholesterol (also known as the “bad” cholesterol) and a decrease in HDL cholesterol (also known as the “good” cholesterol).

Finally, trans fats cause problems directly in the blood vessels, by affecting the cells that line blood vessel walls, known as endothelial cells. By causing dysfunction in these cells, they set up the vascular system for a host of medical issues, including high blood pressure (hypertension), atherosclerosis, heart attack, and stroke.

Health Impact of Trans Fat Bans

Experts at the World Health Organization and elsewhere have noted that policy measures that eliminate trans fats in processed foods can be considered a population-based intervention that would help address one of the dietary risk factors for chronic disease such as obesity, diabetes, and cardiovascular disease. The Centers for Disease Control and Prevention (CDC) has estimated that the complete elimination of artificial trans fats from the diet of Americans could prevent as many as 7,000 coronary deaths and 20,000 nonfatal coronary events.

The country of Denmark banned the use of partially hydrogenated oils in 2003, and several other countries have done the same. In the United States, New York City famously passed a trans-fat ban for restaurants in 2006. The state of California did so in 2008. The FDA is now doing so for the entire United States as of 2015.


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Brownell KD and Pomeranz JL. Perspective: The trans-fat ban—food regulation and long-term health. N Engl J Med 2014; 370:1773-1775.

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