Unsaturated fats with trans-isomer (E-isomer) fatty acid(s) are commonly known as trans fats. Because the term refers to the configuration of a double carbon-carbon bond, trans fats are sometimes monounsaturated or polyunsaturated, but never saturated. Trans fats are rare in living nature, but can occur in food production process.

Fatty acids in foods are made up of polyunsaturated (like safflower oil, sunflower oil and corn oil), monounsaturated (like olive oil, peanuts, and avocados), saturated (like coconut oil, palm oil, butter and cheese) and trans fats (like margarine and shortening). Saturated and trans fats are linked to coronary heart disease. The majority of trans fats are produced by the food industry when it uses a process called hydrogenation to turn liquid vegetable oils into semi-solid products. This process hardens and stabilizes the oils, enhances the flavor and extends the shelf life of food products. These trans fats also break down less easily which makes them more suitable for frying. The majority of trans fats are found in foods made with shortening, margarine or partially-hydrogenated oils and in baked goods like crackers, cookies and donuts and in fried foods like French fries and fried chicken. The trans fat content of some of these foods can be as high as 45% of the total fat in the food product. Trans fats also occur naturally at fairly low levels in ruminant-based foods like dairy products and beef and lamb.

Should we regulate the amount of trans fats contained in the food we eat? In the mid 2000’s a Canadian government task force on trans fats recommended that all vegetable oils and spreadable margarines have the trans fat content limited to 2% of the total fat content and all other foods be limited to a maximum of 5% of total fat content. These new regulations would decrease the average trans fat intake by at least 55%.

Are trans fats worse than saturated fats? There is a lot of evidence linking both trans fats and saturated fats to coronary heart disease. Trans fats appear much more dangerous because metabolic studies have shown that they increase the blood levels of our bad cholesterol (LDL) and decrease the levels of our good cholesterol (HDL). Saturated fats appear less damaging because they elevate the total cholesterol levels – both bad (LDL) and good (HDL). The Harvard School of Public Health found that removing trans fats from the industrial food supply could prevent tens of thousands of heart attacks and cardiac deaths each year in the US. The findings are published in the April 13, 2006 issue of the New England Journal of Medicine. Government organizations around the world have started to act to resolve the problem. In 2002, the US National Academies of Science recommended that trans fat consumption be kept as low as possible. In 2003 the World Health Organization recommended that trans fat intake be limited to less than 1% of overall energy intake. Also in 2003, Denmark set an upper limit on industrially produced trans fats in foods, limiting them to just 2% of the total fats in foods. They excluded meat and dairy products. In 2005 Canada required mandatory labeling of trans fats in packaged foods. The US followed in 2006 with a mandatory labeling for any foods containing 0.5 grams or more of trans fats per serving.

Is mandatory labeling sufficient? Shouldn’t we let informed consumers self-regulate the amount of trans fats they consume? Once the consumer understands how harmful trans fats are and that as little as 5 grams per day can lead to heart disease, then mandatory labeling will force the food industry to reduce the amounts contained in food products much faster than a bunch of government regulations, However what about restaurants and the fast food industry? Here is where the Canadian government task force recommendations are probably a good thing. Consumers do not know how much trans fats there are in French fries, deep fried chicken and baked goods. The recommendation from the June 27th, 2006 final report of the Trans Fat Task Force states – “For all vegetable oils and soft, spreadable (tub-type) margarines sold to consumers or for use as an ingredient in the preparation of foods on site by retailers or food service establishments, the total trans fat content be limited by regulation to 2% of total fat content.” This will people to eat restaurant and fast food industry foods with the knowledge that the trans fat content is limited to 2% or less.

The international trade in food is standardised in the Codex Alimentarius. Hydrogenated oils and fats come under the scope of Codex Stan 19. Non-dairy fat spreads are covered by Codex Stan 256-2007. In the Codex Alimentarius, trans fat to be labelled as such is defined as the geometrical isomers of monounsaturated and polyunsaturated fatty acids having non-conjugated [interrupted by at least one methylene group (-“CH2”-)] carbon-carbon double bonds in the trans configuration. This definition excludes specifically the healthy trans fats (vaccenic acid and conjugated linoleic acid) which are present especially in human milk, dairy products, and beef.

In the USA some major food chains have chosen to remove or reduce trans fats in their products. In some cases these changes have been voluntary. In other cases, however, food vendors have been targeted by legal action that has generated quite rightly a lot of media attention.