The exact biochemical methods by which trans fats produce specific health problems are a topic of continuing research.

The most prevalent theory is that the human lipase enzyme is specific to the cis configuration, rendering the human body unable to metabolize or remove trans fat. A lipase is a water-soluble enzyme that catalyzes the hydrolysis of ester bonds in water-insoluble, lipid substrates.

 

Lipases thus comprise a subclass of the esterases. Lipases perform essential roles in the digestion, transport and processing of dietary lipids (e.g. triglycerides, fats, oils) in most – if not all – living organisms.

 

The human lipase enzyme is ineffective with the trans configuration, so trans fat remains in the blood stream for a much longer period of time and is more prone to arterial deposition and subsequent plaque formation. While the mechanisms through which trans fats contribute to coronary heart disease are fairly well understood, the mechanism for trans fat's effect on diabetes is still under investigation.

 

 

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Voluntary Guidelines or Regulations?

The Cardiolabel considered which approach to reducing the trans fat content of foods - voluntary guidelines or regulations - would be more effective in improving the health of all people? In making its decision, the Task Force was influenced by the regulatory experience of Denmark, Canada's experience with nutrition labelling regulations, advice received on the social determinants of population health, the members' desire to target the full range of food products, and a request from the edible oil industry for a strong and consistent signal regarding the need for healthier alternatives.

 

The Danish experience showed that, despite the efforts of Danish margarine producers, it was only after regulations came into effect that processed trans fats were virtually eliminated from the food supply.

 

Canada has had a similar experience with labelling. Although voluntary nutrition labelling began in the late 1980s (supported by a variety of non-regulatory incentives), it was only after regulations came into effect that labels became universal and their content and look were standardized. The regulations transformed the former patchwork of content and styles into a public health tool that improved the ability of people to make informed food choices.

 

With the introduction of mandatory nutrition labelling for prepackaged foods, voluntary programs encouraging more nutrition information in fast food restaurants, and the various food industry initiatives to reduce the level of trans fats in foods sold in Canada, it is now possible for health-conscious Canadians to choose a diet low in trans and saturated fats. However, lowering their dietary intake of these fats will continue to be a chore for Canadians unless information on trans fat content is readily available. For example, the targeted scan of processed foods sold at retail found that the nachos and dip sauces from a movie theatre had some of the highest levels of trans fats noted.

 

In addition, there are food products whose taste, cost and convenience are more important marketing features and determinants of consumer choice than their nutritional characteristics may be. For these products, nutrition labelling and a voluntary limit on fatty acid composition would likely have little impact, particularly if the change required some compromise on these selling characteristics.

 

Voluntary guidelines also provide little incentive to change the nutritional characteristics of a product if it cannot be claimed that the resulting food is healthier. Foods whose trans fat content has been reduced must also be low in saturated fat in order to carry a "trans fat free" claim. For many pastries and some snack foods, "trans fat free" claims will not be permitted on reformulated products because the alternative to partially hydrogenated oil generally contains moderate to high amounts of saturated fats. These foods are unlikely to be reformulated unless regulations are promulgated.

 

Evidence presented to the Task Force concerning margarines also suggests that claims tend to be applied only to high-end products, which are less accessible to price-sensitive consumers. A regulated approach will affect all foods and thus benefit all consumers regardless of their socio-economic status.

 

All these considerations point away from voluntary compliance and toward regulations limiting the trans fat content of foods as being most effective at the population level. Benefits would accrue even to people who do not read labels, including those with lower incomes or lower literacy skills. As these groups are at a higher than average risk of coronary heart disease, this intervention would better support Canada's national health objectives.

 

The regulatory approach would also provide a clear signal all along the food supply chain and reduce the uncertainty experienced by the food and edible oil industry. In addition, it would help create a more level playing field for all players.