A new article, published in the New England Journal of Medicine (Vol. 354, pp. 1601-1613), reviews the evidence of these fatty acids at both the physiological and cellular level.
Though trace amounts of trans fats are found naturally, in dairy and meats, the vast majority are formed during the partial hydrogenation of vegetable oil that converts the oil into semi-solids for a variety of food applications.
Trans-fatty acids are attractive for the food industry due to their extended shelf life and flavor stability, and have displaced natural solid fats and liquid oils in many areas of food processing.
The authors of the study, from Harvard and Wageningen University in the Netherlands, report that the scientific literature shows that trans fatty acids raises serum levels of LDL-cholesterol, reduces levels of HDL-cholesterol, can promote inflammation can cause endothelial dysfunction, and influence other risk factors for cardiovascular diseases (CVD).
According to the American Heart Association, 34.2 percent of Americans (70.1 million people) suffered from some form of cardiovascular disease (CVD) in 2002.
The reviewers note that, from a nutritional point of view, "the consumption of trans fatty acids results in considerable potential harm but no apparent benefit."
Replacement in the food industry is straightforward, argue the reviewers, and Denmark is the example. The Scandinavian country introduced legislation in 2004 that required locally and imported foods to contain less than two per cent industrially made TFAs, a move that effectively abolished the use of partially hydrogenated vegetable oils in the country.
The reviewers point out that this measure saw the use of cis-unsaturated fatty acids, and some saturated fatty acids, as well as fully hydrogenated vegetable oils in food products.
"Both government and industry representatives agreed that these changes did not appreciably affect the quality, cost, or availability of food," said Mozaffarian.
Closer to home in the US, the introduction of trans fatty acid labeling and increased consumer awareness of trans fatty acid content "may provide an additional impetus for such changes."
"On the basis of experience of Europe, substantial reduction in the use of partially hydrogenated oils appears to be a feasible goal in the United States and could be effected through either legislation or voluntary efforts by food manufacturers," wrote the authors.
The review has been welcomed by Dow AgroSciences, producers of the trans fat-free Natreon canola and sunflower oils, which Dow says rivals the functionality of trans fats in stability for long-term frying.
"We recognize the rapidly increasing demand in the manufacturing and food service industries for healthy, highly stable, trans fat-free oils," said David Dzisiak, global business leader for oils at Dow AgroSciences.
The company recently announced it would double its Natreon canola and sunflower oil production capacity during the next 18 months to more than 1.2bn pounds by 2007.
"This ramp up in Natreon production can make a significant contribution to rapidly removing trans fats from the food supply," said Dzisiak.