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What Are Trans Fats and Why Are They Bad For You?

Despite its negative association to health, the diet needs fat to allow the body to carry out essential functions. Although trans fat, especially, should be used with caution. So what exactly are trans fats and why are they bad for you?


Fat is often feared related to its thrown out use to describe overweight and obesity. But despite its negative association to health, the diet needs fat to allow the body to carry out essential functions. Like any nutrient, though, its nutritional intake should depend on the amount and type. Trans fat, especially, should be used with caution. So what exactly are trans fats and why are they bad for you?

Defining Trans Fat

Trans fats, also known as trans fatty acids, occur in two forms: naturally or chemically produced. In nature, trans fats may be found in meat and dairy products in the presence of bacterial enzymes. However, industrial trans fats are mostly consumed in the North American diet and raise the most concern when it comes to health. Trans fats mostly surfaced when food manufacturers realized solid fats increase both shelf-life and flavor stability in many baked and packaged foods, or in these top five foods for trans fat.

To accomplish the desirable characteristics, liquid oils became manipulated by adding hydrogen (coining its alter name of hydrogenated oil) and reconfiguring its chemical makeup - specifically from a cis configuration to trans, hence the name of trans fat. The alteration ultimately produces a more stable product and bares its use within the food supply. And though the resulting characteristics of trans fat may appear desirable, there is no nutritional benefits of eating trans fats at this time.

Why Are They Bad for You?

Though most nutrition experts try to stray away from classifying foods into "good" and "bad" categories, trans fats are the exception to the rule. In fact, the U.S. Food and Drug Administration (FDA) coined the year 2018 to strip trans fat from the food supply. Research claims and statistics suggest a high intake of trans fat...

...raises low-density lipoprotein (LDL) or "bad" cholesterol in the blood, which may build plaque in the artery walls. Also known as atherosclerosis, too much plaque can obstruct airways and cause a clot to rupture. Atherosclerosis can ultimately lead to a heart attack or stroke, and may even be fatal.

...lowers high-density lipoprotein (HDL) or "good" cholesterol. HDL cholesterol helps move the "bad" cholesterol out from the artery walls, ultimately facilitating its excretion from the body.

...increases the risk of type 2 diabetes, mostly related to a prediabetic condition called insulin resistance, in which cells are unable to efficiently respond to insulin. Insulin plays a key role in assisting glucose from the blood into the body's cells. Without normal responses from insulin, glucose builds up in the bloodstream, creating high blood sugar (hyperglycemia).

Even more specifically, statistics suggest individuals with a high intake of trans fat...

...are 21 percent more likely to develop heart disease.

...increase their risk of heart attacks as much as one and a half times while growing the risk of heart disease mortality (or death) by 28 percent.

...have a 34 percent risk of overall mortality compared to those with a lower trans fat intake. Overall mortality simply translates to death related to all causes.

Ending on good news, the FDA believes eliminating trans fat could prevent an estimated 20,000 heart attacks and 7,000 deaths from heart disease annually.

How Much Is Enough?

Until trans fat is diminished within the food supply, the U.S. Dietary Guidelines suggest no more than 1 percent of daily calories to come from trans fat products. This ultimately translates to approximately two grams each day based on a 2,000-calorie diet. Limiting saturated fat is also stressed with a daily intake of less than 7 percent or about 16 grams and 140 calories. Naturally limit saturated and trans fat by filling the diet with whole grains, including whole grains, fruits and veggies, lean proteins, milk and dairy products, nuts and seeds, and olive and canola oils.

Written By Christy Zagarella, MS, RDN. Published on November 07, 2012. Updated on October 25, 2017.


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