Beware of trans fats

No question about it. Trans fats are bad for us. Something we have known for quite some time, but not been doing that much about. Food authorities in many countries have issued warnings but hoped for voluntary action by the food industry to reduce the trans fat in their products. To a part this has also happened but not enough has been done. It is believed that current intake remains a public health concern.

A few countries, the first being Denmark, did ban trans fats, but now there is a further call for action. The Food and Drug Administration (FDA) in the USA has finally started to move by issuing a preliminary determination that partially hydrogenated oils are no longer GRAS.  That is they are not generally recognised as safe (GRAS) and will require premarket approval should the preliminary determination be finalised. This could start a ripple effect in many other countries.

So what are we talking about?

Subtle changes in fat structure - trans to the left and cis to the right (Photo: Wikimedia)

Subtle changes in fat structure – trans to the left and cis to the right (Photo: Wikimedia)

Trans fats are formed when vegetable oils are treated with hydrogen, changing their chemical composition. This process allows the liquid oil to remain solid at room temperature, preventing biscuits and cakes from going soggy and extending their shelf life. In chemical terms, trans fat is a fat molecule that contains one or more double bonds in trans geometric configuration. A double bond may exist in one of two possible configurations: trans or cis. In trans configuration, the carbon chain extends from opposite sides of the double bond, whereas, in cis configuration, the carbon chain extends from the same side of the double bond. The trans molecule is a straighter molecule. The cis molecule is bent.

The cis configuration is the natural form of unsaturated fatty acids. The process of hydrogenation adds hydrogen atoms to unsaturated fats, eliminating double bonds and making them into partially or completely saturated fats. Typical commercial hydrogenation is partial in order to obtain a mixture of fats that is solid at room temperature, but melts upon baking or consumption to make the food product taste that special extra. And in here lies the problem. Partial hydrogenation converts some of the cis configuration into trans-unsaturated fats instead of hydrogenating them completely.

And to the damage of trans fats

Sorry for the complex background but to understand the issue it is important to know what we are talking about. With the chemistry out of the way it is time to look at the bad effects of trans fats.

Various studies have over some time now linked trans fats to heart disease. A 2002 report by the National Academy of Science’s Institute of Medicine in the USA found a direct correlation between intake of trans fat and increased levels of low density lipoprotein (LDL) cholesterol, commonly referred to as “bad” cholesterol, and, therefore, increased risk of heart disease. And as if this was not enough, trans fats also lowers the levels of the high density lipoprotein (HDL) cholesterol, the so called “good” cholesterol that you actually want.

The Centers for Disease Control and Prevention in the USA estimates that a further reduction of trans fat in the food supply can prevent an additional 7,000 deaths from heart disease and up to 20,000 heart attacks each year in the American population. It is also expected that rates of diabetes, obesity, and some other ailments might be reduced as well.

Where can we find the trans fats?

Donuts (or doughnuts) often culprits with trans fat (Photo: Eric Herot)

Donuts (or doughnuts) often culprits with trans fat (Photo: Eric Herot)

More than a decade ago with the initial trans fat debate consumers started to avoid foods with trans fat and companies responded by reducing the amount of trans fat in their products. However, there are still many processed foods made with partially hydrogenated oils, the major dietary source of trans fat in processed food. Trans fat can still be found in such processed foods as crackers, cookies, cakes, frozen pies and other baked goods. Certain products such as microwave popcorn, shelf stable cakes and donuts are likely to have a higher content. It can also be found in chicken nuggets, frozen pizza, coffee creamers and vegetable shortenings.

Actually, some trans fats can be found naturally at low levels in meat and dairy products. Natural trans fats, which include conjugated linoleic acid and vaccenic acid, originate in the rumen of cattle and sheep and can comprise 2–5% of total milk and body fat. There is still debate about the harmfulness of such natural trans fats but the most convincing evidence points to their inclusion on the harmful side.

What can you do?

In waiting for further action from food authorities and the the industry there are a few things you can do. If there is compulsory label requirements you should look out for any trans fat levels declared. If not it could pay off to look at partially hydrogenated oils in the ingredient list. Thing is that products containing less than 0.5 grams of trans fats might in many circumstances be rounded down to zero. But if there is partially hydrogenated oil listed with the ingredients, there might be a small amount of trans fat. Selecting foods with even small amounts of trans fat can add up to a significant intake.

So be careful in your food choice and don’t eat donuts or microwave popcorn too often.

Related articles

Are trans fats old hat?

Trans fatty acids in the diet was a hot topic for debate started around two decades ago. Trans fats occur both naturally in some animal products like butter, cheese and meat and as industrially modified vegetable fats to create spreads such as margarine, cooking fats for deep-frying and shortening for baking. Trans fat in the form of partially hydrogenated vegetable fat is used by food manufacturers because it is cheap, shelf-stable, and can withstand high temperatures during processing. The major issue at that time was the industrially produced trans fats, although later similar suspicions have been raised also to naturally occurring trans fats.

Heart disease from trans fats in the diet (Photo credit: Gabriela Camerotti – Flickr)

In an opinion published in 2004, the European Food Safety Authority endorsed findings that linked high levels of trans fat in the diet with increased risk of heart disease, as it increases levels of bad cholesterol in the blood. Trans fats might also decrease the levels of good cholesterol, making the situation even worse.

Action has been taken in some countries. In 2003, Denmark became the first country to introduce laws regulating the sale of many foods containing trans fats, a move which effectively bans partially hydrogenated oils. The limit set was 2% of fats and oils destined for human consumption. In 2005, Canada introduced mandatory labelling of all trans fats for pre-packaged food. Argentina and Brazil enforced mandatory labelling of trans fats in 2006, later followed by strict but variable limits for different foods. Similarly, the USA introduced mandatory labelling of prepackaged food in 2006, followed by a legislative limit of 0.5 grams of trans fats in a standard serve of packaged food or a restaurant meal in New York City in 2008 and in California in 2011. Other regions in the USA introduced similar actions. In 2009, Austria and Switzerland and in 2011 Iceland introduced a legislative limit similar to the Danish limit, soon to be followed also by Sweden. Australia and New Zealand organised round table discussions with industry and concerned organisations starting in 2007 to encourage voluntary reductions in the use of trans fats.

Trans fats can be found in fast food (Photo credit: angels – Flickr)

Now researchers from Copenhagen University Hospital and the University of Copenhagen have looked at the impact of the actions taken by different governments and pressure from the public debate over the last decade on the use of industrial trans fats. They analysed samples of foods from across Europe including French fries, chicken nuggets, microwave popcorn, and  samples of biscuits, cakes and wafers which listed partially hydrogenated vegetable fat, synonymous with trans fats, high on the ingredient list. The researchers designed a high trans fat menu from the tested foods and found that in 2009, people in Hungary, Poland and the Czech Republic could still consume 10-20 g of trans fat in a high trans fat menu – although this was an improvement from more than 30 g in 2005. For people in Germany, France and the UK, the same menu provided less than 2 g of trans fat in 2009, down from 20-30 g four years earlier.

So on the bright side the researchers pointed out that, although on a population level trans fat consumption might now be low, there were still sub-populations in some countries with a very high consumption. They wrote that in 2009, only two EU countries – Austria and Denmark – protected their populations from excessive trans fat consumption with specific legislation. All others relied on food producers to voluntarily reduce trans fat in their foods. And obviously the societal pressure was different in different countries.

The World Health Organisation recommends that trans fat should account for less than 1% of total calories. What’s the situation in your country? Look out for ingredients like ‘partially hydrogenated vegetable fats’.