Hydrogenated oil comes in two forms: partially or fully hydrogenated. One use of hydrogenated oil is to preserve the shelf life of food. Partially hydrogenated oil contains trans fat that can raise cholesterol and result in health complications.

In 2015, the Food and Drug Administration (FDA) said that partially hydrogenated oil is not safe, and removing it from food could prevent thousands of heart attacks each year.

The following article discusses what hydrogenated oil is, the types, why artificial trans fat is bad, and why food manufacturers use hydrogenated oil in foods.

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Hydrogenated oil is a type of fat that food manufacturers use to keep foods fresher for longer. Hydrogenation is a process where manufacturers add hydrogen to a liquid fat, such as vegetable oil, to turn it into a solid fat at room temperature.

There are two types of hydrogenated oil: partially hydrogenated and fully hydrogenated.

Partially hydrogenated oil (trans fat)

In the past, manufacturers added partially hydrogenated oils to processed foods.

According to the FDA, foods that used to contain large amounts of artificial trans fat include:

  • most baked goods
  • stick margarine
  • frosting
  • coffee creamers
  • snack foods

In 2015, the FDA declared that trans fat is not “generally recognized as safe” and had to be phased out by 2018.

However, trans fat may still be present in some foods. According to the American Heart Association (AHA), trans fat occurs naturally in certain animals, such as cows.

Fully hydrogenated oil

Fully hydrogenated oil also uses a process to take a liquid oil and transform it into a solid at room temperature. As the name suggests, the oil is fully or nearly completely hydrogenated, which reduces the amount of trans fat in the final product.

Unlike partially hydrogenated oil, the FDA still allow products to use fully hydrogenated oil as of 2018.

In 2020, the FDA released certification that states fully hydrogenated rapeseed oil is safe for sparing use in food products.

Though hydrogenated oils may be safe, it does not mean they are necessarily good for a person to consume. Products that contain them are often highly processed with added sugar and salt.

A person should still avoid foods that use hydrogenated oils and opt for fresh fruits, vegetables, whole grains, and lean proteins instead.

Food manufacturers use hydrogenated oil as a preservative. They also use it for enhancing flavor and texture.

According to AHA, food manufacturers add hydrogenated oils to foods for several reasons, including:

  • cutting costs
  • preserving foods
  • enhancing texture
  • enhancing taste

Instead of using trans fat or partially hydrogenated oils, manufacturers use a combination of different oils to enhance taste and texture.

Hydrogenated oil, particularly partially hydrogenated oil, has a number of potential side effects that can negatively affect a person’s health.

According to the FDA, trans fat can raise people’s low-density lipoprotein (LDL) cholesterol. This is also known as “bad cholesterol.” Higher LDL cholesterol levels increase a person’s risk of developing heart disease, which is the leading cause of death in the United States.

The AHA add that trans fat can also reduce levels of high-density lipoprotein (HDL) cholesterol. This is known as “good cholesterol.” The increase in LDL cholesterol and decrease in HDL cholesterol can raise the risk of a person developing heart attack, stroke, and type 2 diabetes.

An older study of over 400 women found that consuming trans fat increased their risk of developing insulin resistance.

As manufacturers no longer use partially hydrogenated oil and trans fat in their processes, they have switched to using a combination of oils, including fully hydrogenated oil.

Foods that contain higher levels of hydrogenated oils include:

  • canned frostings
  • baked goods
  • margarine sticks
  • coffee creamers
  • snack foods

Some of these foods may still contain a small amount of trans fat as a result of the manufacturing process.

Since hydrogenated oil is found in highly processed foods, a person should avoid hydrogenated oil as much as possible.

Learn more about healthful cooking oils here.

The AHA recommend a person includes these foods in their diet:

  • whole grains
  • non-tropical vegetable oils
  • unsweetened dairy
  • variety of fruits and vegetables
  • skinless poultry
  • fish
  • legumes

They also recommend a person avoids:

  • sugar-sweetened beverages
  • foods with added sodium
  • foods high in saturated fat
  • foods containing some trans fat

In other words, a person should avoid eating highly processed food, such as fast food, baked goods, and other foods high in saturated fat, hydrogenated oils, salt, and sugar.

Many processed foods contain hydrogenated oil to increase shelf life and enhance flavor.

There are two types of hydrogenated oil: partially and fully hydrogenated. Partially hydrogenated oil contains trans fat and manufacturers can no longer add it to foods in the U.S.

Manufacturers can still use fully hydrogenated oils in their manufacturing processes. However, foods containing these oils are still not a healthful option, so people should try to avoid them.

The easiest way to avoid hydrogenated oil is to avoid processed foods. A person should make whole foods, including vegetables, fruits, nuts, lean protein, and unsweetened dairy, part of a regular diet.