What is Trans Fat?

Trans fats are unsaturated fats produced from vegetable oils. They are commonly used in the preparation of margarine and commercially baked or fried foods.

Fast food is often high in trans fat.kazoka | Shutterstock

There are two forms of trans fat - naturally-occurring and artificial trans fats. Artificial trans fats are man-made fats produced through a chemical process called hydrogenation. Naturally-occurring trans fats can be found in many animal products, including milk and meat.

How are trans-fat produced?

Artificial trans fats are a by-product of a chemical process called hydrogenation. Hydrogenation is used to turn vegetable oils into solids to improve shelf life. This chemical process changes the degree of saturation of the fat and converts the liquid oils into solid or semi-solid forms. The resultant product remains solid at room temperature and is called partially hydrogenated oils. Hydrogenation preserves foods, making them less likely to spoil. This method is also relatively cheap and imparts a desirable taste to food.

Why are trans fats considered to be unhealthy?

Trans fat confers no health benefits; instead, it is associated with a high risk of developing a plethora of diseases.

Cardiovascular disease (CVD)

People who regularly eat trans fats are more likely to suffer from heart disease and stroke. Trans fats affect blood cholesterol levels by raising LDL cholesterol (bad cholesterol) and triglycerides and lowering HDL cholesterol (good cholesterol).

Trans fats cause systemic inflammation, increased formation of blood clots, and reduced endothelial function or vascular relaxation - all contributing to increased cardiovascular risk.


Trans fats also contribute to insulin resistance and thus elevate the risk of developing type 2 diabetes.

Carcinogenic (cancer-causing) properties of trans fats

Trans-fat has also been linked to breast cancer development. A study conducted by Kohlmeier et al., found a positive association of body stores of trans fatty acids and breast cancer development in postmenopausal European women; however, this fact requires confirmation in other populations too.

Trans-fatty acids have also been hypothesized to increase the risk of colon cancer. Alteration of immune response, cell wall integrity, and impairments in prostaglandin synthesis are some reasons postulated for the same.

Pregnancy complications

Trans fat can cross the placenta and cause fetal impairments. A high intake of trans fatty acids has also been associated with the risk of preeclampsia – a condition characterized by high blood pressure and protein in the urine.


As per a study by Weiland et al., trans fat increases the incidence of allergic conditions such as asthma, allergic cold, and eczema. Due to these adverse effects, several countries such as Denmark, Switzerland, Canada, Britain, and the United States have reduced or restricted the use of trans fats by the food industry.

The American Heart Association (AHA) recommends reducing the intake of foods containing partially hydrogenated vegetable oils. AHA suggests preparing meat without added saturated and trans fat.

The US FDA (Food and Drug Administration) has also taken steps to remove artificial trans fats in processed foods. In 2015, FDA determined that partially hydrogenated oil, are not “Generally Recognized as Safe,” or GRAS.

The World health organization (WHO) has also launched a campaign to eliminate the use of trans fat, especially in emerging economies of South Asia.

Which foods contain trans fat?

Trans fat is found in most of the commercially available fried and baked foods. Cakes, frozen pizza, tortilla chips, cookies, crackers, biscuits, coffee creamer, and margarine are loaded with trans-fat. The amount or percentage of trans fat in a particular packaged food can be determined by reading the nutrition facts panel. Trans fat can also be checked by referring the ingredient lists and looking for components termed partially hydrogenated oils.

How to reduce the consumption of trans fat.

The American Heart Association recommends the following ways to reduce the consumption of trans fat.

  1. Food labels help the consumers’ intake of additives such as trans-fat. When buying processed foods, opt for one with unhydrogenated oil rather than partially hydrogenated oils.
  2. Nuts and fish contain a high amount of unsaturated omega-3 fatty acids and are thus good choices of healthy fats.
  3. Eat a diet rich in fruits and green leafy vegetables. Include proper proportions of whole grains, low-fat dairy products, poultry, fish, and nuts. Limit the consumption of red meat and sugary foods and beverages.
  4. Consider using healthier oils when cooking. Vegetable oils such as canola oil, sunflower oil, and olive oil are some naturally occurring unhydrogenated oils.
  5. Limit the consumption of commercially fried foods and baked goods. Processed food with alternatives sources of fat with zero trans-fat levels should be selected.


  • American Heart Association. (2017) Trans Fats. heart.org.
  • Mayoclinic. (2017) Trans fat is double trouble for your heart health. mayoclinic.org.
  • Iwata, N. G et al., (2011) Trans fatty acids induce vascular inflammation and reduce vascular nitric oxide production in endothelial cells. PloS one, 6(12), e29600. doi:10.1371/journal.pone.0029600
  • Dhaka, V et al., (2011). Trans fats-sources, health risks and alternative approach - A review. Journal of food science and technology, 48(5), 534–541. doi:10.1007/s13197-010-0225-8

Further Reading

Last Updated: Jun 18, 2019

Yolanda Smith

Written by

Yolanda Smith

Yolanda graduated with a Bachelor of Pharmacy at the University of South Australia and has experience working in both Australia and Italy. She is passionate about how medicine, diet and lifestyle affect our health and enjoys helping people understand this. In her spare time she loves to explore the world and learn about new cultures and languages.


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