ARCHIVED - Health Canada Scientist Leads Trans Fat Research
Trans fats are big news these days.
Trans fat has negative health effects on the level of blood lipids which are major risk factors for coronary heart disease. These effects are stronger than those of saturated fatty acids. According to the Harvard School of Public Health, trans fats cause between 30,000 and 100,000 premature deaths annually in the United States.
What exactly are trans fats? Simply put, they are a type of fat formed when food manufacturers turn liquid oils into solid fats using a process called "partial hydrogenation." Trans fats also exist naturally as a small percentage of the total fat found in dairy and meat products.
During the 80's and 90's, partially hydrogenated oils became popular among commercial food makers because it's cheaper to use than other fats and prolongs the shelf life of products. Since then, processed food is the major source of trans fat in the North American diet. This trend is beginning to reverse.
Discovering a Method for Reliably Identifying Trans Fats
Many foods in Canada list the amount of trans fats on their labels. However, it was only recently that we've been able to reliably identify trans fat. One of the biggest challenges was distinguishing trans fats from similar molecules called cis isomers.
It was one of Health Canada's very own scientists, Dr. Nimal Ratnayake, who discovered how to accurately determine trans fatty acid content in dietary fats and animal tissues. In fact, his innovative method is now considered the international standard for measuring trans fats in food.
He combined a scientific process called gas chromatography with a second process, silver ion thin layer chromatography. These charged ions help separate the cis and trans molecules, which otherwise would be impossible to differentiate.
The remarkable column he uses to separate the molecules is very long. While it measures 100 meters long, it is just .25 mm thick!
Estimating the Consumption of Trans Fats by Canadians
Ratnayake has also performed extensive research on the quality of fat in the Canadian diet. Thanks to his work, we now know that we are possibly the highest consumers of trans fats in the world.
In fact, his work played a key role in the move by Health Canada to require mandatory nutritional labelling of trans fatty acids in foods sold in Canada.
Ratnayake found that the average Canadian consumed 8.4 g of trans fatty acids per day, which amounted to 10% of total fat intake (recommended intake is less than 2%). Remarkably, Canadian men aged 18 to 34 ate an average of 38.9 g of trans fatty acids a day.
These levels of trans fat consumption were higher than levels reported by other countries, including Britain, Germany and the United States. And they were more than triple the average levels of consumption in countries such as Portugal, Italy and Greece.
Trans Fatty Acid Content in Human Adipose (Fat) Tissue Samples From Various Countries
So how did Ratnayake discover this disturbing news?
He used a combination of laboratory and statistical methods to estimate the Canadian consumption levels, and then compared them with other countries. He looked at the levels of trans fatty acids in human fat tissue and breast milk. He analysed data from Canadian nutrition surveys and developed estimates based on Canadian market share data. He also analysed the trans fat levels in a combination of foods reflecting an average Canadian diet.
Ratnayake's studies also showed that processed foods, such as packaged cakes, microwave popcorn, store-bought cookies and crackers, and fast food were the major sources of trans fatty acids in the Canadian diet. Although trans fats do exist naturally in dairy and meat products, they contributed only a small proportion to the total amount of trans fats consumed.
Visit our main trans fat page for more information.
Did you know?
In January 2003, Canada became the first country to pass legislation requiring mandatory declaration of the trans fatty acid content of foods. Labelling of trans fats will be compulsory for most pre-packaged foods by December 2005.
Recently, the House of Commons passed a motion calling for a task force to develop recommendations and strategies for reducing processed trans fats in Canadian foods to the lowest levels possible. It also urges the government to enact regulations or a law limiting these trans-fats in all food products.
Health Canada, in conjunction with the Heart and Stroke Foundation of Canada, will work with the task force to develop ways to reduce trans fats in Canadian foods to the lowest levels possible.
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