What is trans fat?

What is trans fat?

Pawel Malczewski
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Short Summary

Industrial Trans fatty acids (iTFAs) have been used in processed foods for over a century. For the last four decades, strong evidence has started to show that they are detrimental to our health. However, only in the last decade, have a small number of countries started to undertake steps to reduce or eliminate iTFAs from our diets.

This article discusses industrially produced trans fats, their history and the most effective methods for eradicating them from the supermarket shelves and from our diets. For a quick answer click here.

Explanation

Trans fats come from 3 sources:

  • They can be generated through a process called partial hydrogenation. Most of the trans fatty acids in our diet have this origin.
  • They are a consequence of some cooking methods that require high temperatures and/or reheating oils. The amount of iTFAs that originate through this method fall below the safe recommended limits.
  • Trans fats naturally occur in milk and other dairy products and the meat of ruminant animals, but are considered safe in the amounts naturally found in these foods.

What are trans fats?

This article focuses on industrial trans fatty acids since they have a significant impact in our health. Natural trans fats from ruminants are covered in another article.

In general, iTFAs can be thought of as damaged fats.

The iTFAs mainly consist of stearic, oleic and elaidic acids which melt at 108 Fahrenheit (42 degrees Celsius) and are, therefore, solid at room temperature and inside the human body.

Trans fatty acids are straight chains of carbon and hydrogen molecules that can align closely together, mimicking saturated fats. This tight alignment increases the melting point. (1)Song J, Park J, Jung J, Lee C, Gim SY, Ka HJ, et al. Analysis of Trans Fat in Edible Oils with Cooking Process. Toxicol Res. 2015 Sep; 31(3): 307–312. Available here.

iTFAs have a slightly different chemical structure compared to naturally occurring trans fatty acids (rTFAs). This difference is thought to exert different effects on our body.

Studies on rTFAs are very limited.  There is currently not enough knowledge to clearly pinpoint the differences in the health effects when measured gram for gram. Available studies didn’t find any evidence between rTFAs and negative health effects. It is even believed that they might have a positive effect on health.

However, there are numerous studies on iTFAs . They show a clear link to cardiovascular diseases, cancers and other serious health issues.

Short history of iTFAs

iTFAs didn’t exist, or existed only in trace amounts, in foods before the invention of partial hydrogenation in the early 1900s.

During the 1920s, partial hydrogenated oils (PHOs) became a common component of frying fats, margarines and shortenings.

The consumption of iTFAs started to increase after World War II and reached its peak in the 1970sand 1980s, when margarines were advertised as a healthier alternative to saturated-fat butter. (2)Liska DJ, Cook CM, Wang DD, Gaine C, Baer DJ. Trans fatty acids and cholesterol levels: An evidence map of the available science. Food and chemical toxicology. Volume 98, Part B, December 2016, Pages 269–281. Available here.

The concerns of their health effects started soon after iTFAs invention. However, solid scientific evidence only started to emerge about four decades ago. In the 1990s, it was shown that iTFAs increase LDL cholesterol and decrease HDL cholesterol. (3)Stender S. In equal amounts, the major ruminant trans fatty acid is as bad for LDL cholesterol as industrially produced trans fatty acids, but the latter are easier to remove from foods. Am J Clin Nutr December 2015. vol. 102 no. 6 1301-1302. Available here.

In Denmark, iTFAs almost disappeared after 2003/2004, when a total ban was introduced. Some European countries also introduced a total ban, after Denmark’s success in eradicating them.

The consumption of trans fats in the United States dropped drastically after the introduction of compulsory labelling. In 2016, it was estimated that there was an average consumption of 1g per day (0.5% of the daily energy intake). PHOs will be totally phased out by 2018. (4)FDA – U.S. Food and Drug Administration. Final Determination Regarding Partially Hydrogenated Oils (Removing Trans Fat). Available here.
There are relatively few countries with bans on iTFAs and PHOs or with labelling laws that impose the disclosure of all components. In other countries, where consumers are health conscious and where manufacturers voluntarily reduce these fats, it is expected that trans fats will effectively disappear from foods. However, in countries where the voluntary reduction doesn’t work (such as the Balkan countries), an increase of iTFAs is noted in the products. (read more..)

What are the most consumed sources of industrial trans fats?

The largest amounts of iTFAs are found in vegetables spreads, shortenings and baked products that use PHOs. For a comprehensive list of foods that contain high amounts of iTFAs, please read the article (read more..).

Stir frying and deep frying in high temperatures also generates some trans fats, but in comparatively  very small quantities, although it may add to our daily intake of trans fats. (read more..)

How helpful are the trans-fat and PHO bans?

A ban on industrial trans-fat usage is the most effective method of insuring that these substances are not posing health risks in our society.

Various countries have introduced different methods to reduce trans fats such as: (5)World Health Organization Europe. 2015. Eliminating trans fats in Europe. A Policy Brief. Available here.

  • mandatory labelling of packaged goods, including information on the trans fats or partially hydrogenated oil contents to enable the public to make informed choices
  • encouraging manufacturers to voluntarily change their food processing methods
  • imposing trans-fat and/or PHO bans

Compulsory labelling

Compulsory labelling for iTFOs and PHOs is somewhat, but not 100%, effective in restricting trans fats from our diet. Many customers are not familiar with the terminology used on the labels or on the ingredients list and some labelling laws have loopholes, allowing manufacturers to conceal the real iTFOs and PHOs contents. (read more..)

Voluntary changes in food production

In some countries, the government encourages manufacturers to reduce or eliminate the production of partially hydrogenated oils and assumes society’s pressure that will occur naturally.

While some in countries PHOs usage has been reduced successfully (e.g. Australia, NZ, Germany and UK) (6)World Health Organization Europe. 2015. Eliminating trans fats in Europe. A Policy Brief. Available here.
, this method doesn’t seem to work in other countries (e.g. Serbia, Croatia, Bosnia and Hercegovina). Voluntary reduction initiatives seem to work, but not in all the countries that have adopted it.

Please note, however, that without enforced restrictions, there are no guarantees that the foods you eat don’t contain high amounts of iTFAs. (7)Steen Stender. Industrially Produced Trans Fats and the New Nordic Diet, by Steen Stender. Coursera. Lecture 23 – 7.3 Available here.

Ban on using trans fats and PHOs

A total ban on PHOs and strict restrictions of iTFAs, insure that we can safely consume any products without exceeding the safe levels of these substances.

In some countries, such as Denmark, Switzerland, Austria, Iceland, Hungary and Norway, PHOs are not allowed in foods and a limit of 2g of iTFA per 100g of fat is applied. In the United States, the use of partially hydrogenated fats and oils will be phased out completely in 2018. (8)FDA – U.S. Food and Drug Administration. Final Determination Regarding Partially Hydrogenated Oils (Removing Trans Fat). Available here.
The amounts of trans fats are often very high in the most popular junk food snacks, making them even more unhealthy.

The following example shows how much iTFAs are consumed from three popular junk foods. The study was done in 2008 and presents the trans fatty contents used in different countries. (9)Stender S, Astrup A, Dyerberg J. Ruminant and industrially produced trans fatty acids: health aspects. Food Nutr Res. 2008; 52: 10.3402/fnr.v52i0.1651. Available here.

At the bottom of the graph, it is clear that there was a reduction in trans-fat contents in these products after Denmark applied a ban in 2003/2004.

Fortunately, in the United State, the PHOs will disappear after 2018 due to legislation introduced in 2015 to phase them out completely. This, unfortunately, cannot be said about Australia, New Zealand and many other countries which don’t plan any restrictions of iTFAs.

Contents of trans fats in common junk food

It is not surprising that the elimination of trans fats from foods, corresponded with a significant reduction in the mortality rates related to cardiovascular diseases (CDV). Every year, since the ban in Denmark, there are on average 14.2 less deaths per 100,000 people caused by CDV. (10)Restrepo JB, Rieger M. Denmark’s Policy on Artificial Trans Fat and Cardiovascular Disease. Am J Prev Med. 2016 Jan;50(1):69-76. Available here.
The following graph presents the reduction in the mortality rates of coronary artery disease. Although is not a proof that the mortality reduction is exclusively due to the ban on trans fats, it certainly played an important role. (11)Steen Stender. Industrially Produced Trans Fats and the New Nordic Diet, by Steen Stender. Coursera. Lecture 23 – 7.3 Available here.

Mortality rate of coronary artery disease by country

Australia and New Zealand

Countries, such as Australia and New Zealand, don’t plan to implement a ban or impose any restrictions on iTFAs or PHOs use.  This is due to fear that manufacturers will replace trans fats with other harmful ingredients, such as more sugar, making matters worse.

Lab tests were performed on food samples from supermarkets. Based on this information, the consumption of trans fatty acids in Australia is estimated to be 0.5-0.6% of the total energy intake, which is below the recommended limit. (12)World Health Organization Europe. 2015. Eliminating trans fats in Europe. A Policy Brief. Available here.

Please note, however, that this does not guarantee that all products are safe to eat.  Manufacturers are not legally obliged to limit iTFAs in their foods. This means that if you are unlucky with your choices, you might be potentially far exceeding the daily safe limits of trans fats.

Conclusion

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Industrially produced trans fats are harmful and should be avoided.  While it is safe to consume fats without fear of exceeding trans fats intake in countries with a total ban, you have no such guarantee in countries that only apply labelling restrictions or count on a voluntary trans-fat reduction.  In this case, the safest way to insure a minimal intake of iTFAs is by avoiding processed foods that contain fat, and cook using whole foods and non-processed ingredients.

Familiarizing yourself with the labels and labelling legislation in your country is also helpful, although it is not 100% effective, due to loopholes in the rules.

References   [ + ]

1. Song J, Park J, Jung J, Lee C, Gim SY, Ka HJ, et al. Analysis of Trans Fat in Edible Oils with Cooking Process. Toxicol Res. 2015 Sep; 31(3): 307–312. Available here.
2. Liska DJ, Cook CM, Wang DD, Gaine C, Baer DJ. Trans fatty acids and cholesterol levels: An evidence map of the available science. Food and chemical toxicology. Volume 98, Part B, December 2016, Pages 269–281. Available here.
3. Stender S. In equal amounts, the major ruminant trans fatty acid is as bad for LDL cholesterol as industrially produced trans fatty acids, but the latter are easier to remove from foods. Am J Clin Nutr December 2015. vol. 102 no. 6 1301-1302. Available here.
4. FDA – U.S. Food and Drug Administration. Final Determination Regarding Partially Hydrogenated Oils (Removing Trans Fat). Available here.
5. World Health Organization Europe. 2015. Eliminating trans fats in Europe. A Policy Brief. Available here.
6. World Health Organization Europe. 2015. Eliminating trans fats in Europe. A Policy Brief. Available here.
7. Steen Stender. Industrially Produced Trans Fats and the New Nordic Diet, by Steen Stender. Coursera. Lecture 23 – 7.3 Available here.
8. FDA – U.S. Food and Drug Administration. Final Determination Regarding Partially Hydrogenated Oils (Removing Trans Fat). Available here.
9. Stender S, Astrup A, Dyerberg J. Ruminant and industrially produced trans fatty acids: health aspects. Food Nutr Res. 2008; 52: 10.3402/fnr.v52i0.1651. Available here.
10. Restrepo JB, Rieger M. Denmark’s Policy on Artificial Trans Fat and Cardiovascular Disease. Am J Prev Med. 2016 Jan;50(1):69-76. Available here.
11. Steen Stender. Industrially Produced Trans Fats and the New Nordic Diet, by Steen Stender. Coursera. Lecture 23 – 7.3 Available here.
12. World Health Organization Europe. 2015. Eliminating trans fats in Europe. A Policy Brief. Available here.

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