Skip to main content

(And 5 Easy Ways to Never Eat Them Again)

Have you ever wondered what a trans fat really is?

Well, you are not alone.

The subject of trans fat can be confusing and is often misunderstood.

The goal of this article is to help clarify many of the most common questions about trans fats.

We will explain what trans fats are, how they are made, and what makes them different from other fats.

We will also explore why they are bad for us and show you ways to avoid eating them once and for all.

What Is a Trans Fat?

Trans fats (also called trans unsaturated fatty acids or trans fatty acids) are found in nature as well as produced synthetically.

Natural trans fats are produced in the gut of some grazing animals (like cattle and sheep), which is why small quantities of trans fat can be found in animal products like meat, milk and milk products.

According to the official USDA nutrient database, cheese, milk, yogurt, burgers, chicken fat, turkey meat, bologna and hot dogs contain up to about 1-5 percent trans fat.

Trans fat can also be synthetically created by hardening vegetable oil in a process called hydrogenation, which rearranges the atoms, so they behave more like animal fats.

Partially hydrogenated oils (PHOs) are attractive to food manufacturers because they enhance the shelf life, texture and flavor stability of foods—all at a low cost.

Let’s examine how the hydrogenation process alters the composition of fat.

Naturally occurring fats have double bonds: a connection with two bonds, holding one carbon atom to the next in a long chain of carbons. Each carbon on both sides of the double bond has one hydrogen attached to it. Because these two hydrogen atoms are located on the same side of the double bond, it causes the chain to bend.

When you partially hydrogenate, the molecules are rearranged so that the two hydrogen atoms are no longer located on the same side but instead on the opposite (or trans) side of each other. This acts to ‘straighten out’ the carbon chain, making it more solid and tight.

How Many Trans Fats Do We Eat?

In the standard American diet, the average daily trans fat intake is 5.8 grams, representing approximately 2.6 percent of calories consumed.

About half of American’s trans fat intake comes from animal products and half from processed foods that contain partially hydrogenated oils. (PHOs)

Trans fats may be present in many commercially processed, packaged foods, which are made with PHOs.  This includes baked goods, cakes, coffee creamers, cookies, crackers, donuts, fast food, fried food (including French fries), frozen pies, frozen pizza, potato and tortilla chips, ready-to-use frosting, refrigerated dough products, snack foods (including some microwave popcorn), vegetable shortenings and stick margarine.

Why Trans Fats Are Bad for Us

Trans fat was once thought to be healthful and a ‘great boon to Americans’ arteries,’ but research has told another story.

At the end of the day, trans fat is bad for us.

In fact, trans fat is considered to be the worst type of fat you can eat.

According to the National Academy of Sciences, the organization that advises the US and Canadian governments on nutritional science policy, “Trans fatty acids are not essential and provide no known benefit to human health.”

A 2006 analysis published in the New England Journal of Medicine concurs, stating that, “From a nutritional standpoint, the consumption of trans fatty acids results in considerable potential harm but no apparent benefit.

Trans fats increase the risk of heart disease, cancer, obesity, and diabetes. They have even been associated with aggressive behavior, impatience, and irritability.

Specifically, trans fats encourage:

  • Cardiovascular Disease. Unlike other dietary fats, trans fats simultaneously raise your LDL (‘bad’) cholesterol and lower your HDL (‘good’) cholesterol. Because of this, they are a serious threat to our cardiovascular health, increasing the risk of clogged arteries and death from strokes and heart attacks. A 1993 Harvard study strongly supported the idea that eating partially hydrogenated vegetable oils contributed to the risk of having a heart attack. In the study, researchers estimated that replacing just 2 percent of energy from trans fat with unsaturated fat could decrease the risk of heart disease by a whopping 30 percent!
  • Inflammation. We also know that eating trans fat promotes inflammation, a condition linked to a variety of chronic diseases including cardiovascular disease, obesity, cancer, and diabetes.
  • Cancer. Moreover, it appears that trans fats promote cancer. There are two reasons for this. First, the integration of structurally deformed fats into our cells walls can leave gaping holes and, therefore, allow cancer-causing chemicals to enter. Secondly, trans fat also increase the risk of cancer by altering our immune and hormonal systems. Research has shown that for breast cancer patients, consuming trans fats can increase the risk of dying by 78 percent after diagnosis within a 7-year period.
  • Obesity. Finally, trans fat (like all fat) contributes to obesity and obesity-related diseases like type 2 diabetes, arthritis, and hypertension.

So How Many Trans Fats Can We Eat Safely?

According to the National Academy of Sciences, the answer is simple.

The only safe level of trans fat consumption is zero.

The NAS does not set a ‘safe level’ or a “Tolerable Upper Daily Limit” because “any incremental increase in trans fatty acid intake increases coronary heart disease risk.”

And while the NAS recognizes that complete elimination of trans fat might be difficult for those not following a plant-based diet (given its natural presence in animal products), it strongly recommends keeping trans fat consumption as low as possible.

The World Health Organization concurs, advocating that trans fats be limited to less than 1 percent of overall energy intake.

The FDA has taken measures to reduce and/or eliminate trans fat consumption.

Since 2006, it has required that trans fat content is listed on the Nutrition Facts label. And in 2013, the FDA went one step farther. It declared that partially hydrogenated oils (the source of trans fats) are not ‘generally recognized as safe’ (GRAS) and set a 3-year time limit to remove them from all commercially processed foods.

How to Avoid Trans Fat

Here are three easy ways to avoid trans fat consumption.

1. Avoid commercially prepared baked goods, snack and boxed foods as well as fast foods.

Some of the more common foods to avoid include baked goods made with shortening or partially hydrogenated oils, such as cakes, cookies, crackers, fried foods, French fries, muffins, pies, potato chips, shortening, and margarine.

2. Read labels carefully for trans fat content.

While FDA regulation requires that the amount of trans fat be listed on the Nutrition Facts labels, trans fats are only listed when they exceed 0.5 grams per serving. To avoid having to show the trans fat content of a given food, many companies will reduce its serving size.

For example, if a half-cup serving size has a trans fat content of 0.7 gram, it should be listed on the Nutrition Facts label. However, if the serving size is reduced to one-fourth cup, the amount of trans fat drops to 0.35 gram and the food product can be listed as having zero trans fat.

True trans fat content is therefore often ‘hidden,’ which means you could unwittingly eat a fair amount of trans fat without knowing it.

To ensure that you avoid trans fat, it is imperative you do not rely on the Nutrition Facts label only. You should also check the food’s ingredients list for ‘partially hydrogenated vegetable oil.’ If the product contains PHOs, it contains trans fat and should be avoided.

3. Be careful in restaurants, bakeries, and coffee shops.

Since there are no food labels in restaurants, you need to be extra careful with what you eat. Specifically, avoid deep-fried foods since some restaurants still use PHOs in their fryers.  And always ask about the ingredients used to prepare baked goods.

Bottom line?

There is no level of trans fat that is safe. Any trans fat intake above zero increases LDL cholesterol concentration.

This means that any food that contains trans fat should be kept at the lowest level possible and preferably avoided altogether. This includes meat, eggs, and dairy (for non plant-based eaters), and any processed foods, which have been made with partially hydrogenated oils (regardless of the trans fat levels you see listed on the Nutrition Facts label).

The easiest way to eliminate trans fats altogether is to adopt a whole food, plant-based diet that is rich in fruits, vegetables, and whole grains, and is naturally trans fat free!

Rosane Oliveira, DVM, PhD

President & CEO, Plant-Based Life Foundation | Dr. Rosane Oliveira combines a lifelong passion for nutrition with 25 years of genetics research to create programs that help people develop healthy habits on their journey towards a more plant-based lifestyle. She is a Visiting Clinical Professor in Public Health Sciences and was the founding director of the first Integrative Medicine program at the UC Davis School of Medicine. She completed her postgraduate studies in Brazil and did her postdoctoral training in immunogenetics and functional genomics at the University of Illinois at Urbana-Champaign.