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What is Trans Fat? - From the Canadian Food Information Council

Simply put, trans fat is a type of unsaturated fat with physical properties that mimic saturated fat. Trans fats are also known as trans fatty acids and for the purposes of this article these two terms will be used interchangeably.
Trans fat entered the diet and heart disease debate decades ago. Early studies found that high intakes of trans fat increased blood cholesterol levels and thus were associated with an increased risk of coronary heart disease CHD). However, at that time there was equally strong evidence that trans fat did not result in an increase in blood total cholesterol levels.

In the 1990’s, more research from controlled trials with human subjects and from large-scale studies of diet and disease connections strengthened the case against trans fat.

What is trans fat and where do we find it?
Trans fat has the same basic components as all fat molecules—carbon, hydrogen and oxygen. Trans fat is distinguished from other fats by the presence of at least one double bond in the trans configuration The usual configuration in nature is cis.

Naturally occurring trans fats are found in meat and milk, but in small amounts.

The majority of the trans fat we eat comes from processed food products containing hydrogenated or partially hydrogenated oils e.g. hard margarines, shortening, some baked goods, fried foods, and snack foods such as chips and crackers.

Hydrogenation is a chemical process that converts oils—usually vegetable or fish oils—into a more solid form. When used in food processing, these changed oils result in products with greater stability and improved characteristics, such as a desirable texture.

The food industry began to widely use hydrogenation in the 1950’s, although the technique had been around since the early part of the 20th century. There was a desire to replace animal fats with vegetable oils in food products.

What is its role in health and disease?
Trans fat appears to behave like saturated fat, hence producing a negative effect on blood cholesterol levels.

Specifically, research reveals that trans fat raises total blood cholesterol and LDL cholesterol and it decreases HDL cholesterol1. These changes increase risk of heart disease.

How much trans fat do we eat?
Estimates range from 0.5% to 2.6% of energy1, but intakes are difficult to quantify. Not all food databases contain an analysis for trans fatty acid content. In addition, the food supply is changing, with manufacturers removing or reducing use of hydrogenated fats in their products.

A particular challenge with epidemiological investigations that span several years is assessing levels of trans fat intakes in the face of compositional changes in food products.

The most notable marketplace change is in the formulation of margarines, with trans-free choices now available and with the softer, i.e. lower-trans-fat margarines, gaining in popularity.

Trans fat intake also is influenced by the public’s knowledge, perceptions and interests in food. Trans fat stories are trickling into the news. The consumer’s growing awareness of trans fat, combined with the steady barrage of nutrition messages to reduce fat intake, can influence eating behaviour, and conceivably affect the amount of trans fat consumed.

Soon labels on packaged food in Canada will declare trans fat content as part of the new expanded list of nutrients in the Nutrition Facts panel.

The bottom Line
Consumers quickly grasped the lower-your-fat intake message launched in the ‘70’s. Small mention was made of trans fat then. Now, dietary fat advice is complicated by specifics and a focus on individual fatty acids.

People’s diets vary in fatty acid combinations and probably always will. Efforts to focus on one fatty acid over another create practical hurdles for consumers trying to follow dietary advice.

Still, trans fat has more stacked against it than for it. Lowering intakes of trans fat along with lowing intakes of saturated fat remain desirable dietary goals.