No longer "GRAS": The trans fatty acids debate

Major dietary lipids in nutrition and health

In this chapter, an overview of the major lipids in the diet with emphasis in nutritional aspects is provided. Triacylglycerols, i.e., glycerol esterified with three fatty acids, are the predominant constituents in dietary lipids. Therefore, this chapter focuses on the nature and nutritional significance of the main fatty acids in the diet and their possible modifications during food processing and commercialization. The main fatty acids in dietary lipids are grouped into saturated, monounsaturated and polyunsaturated fatty acids. Nutritional implications, the latest intervention trials and health recommendations will be discussed. A brief description of the major sources of lipids in the diet is included, oils and fats standing out. Other food sources shortly commented are milk and dairy products, meat, poultry and eggs, fish, and structured lipids designed to improve functional and nutritional properties. Modifications of fatty acids as a result of processing and commercialization are discussed because of their great relevance for their health implications, especially oxidation compounds and trans fatty acids.

Circulating concentrations and relative percent composition of trans fatty acids in healthy Canadian young adults between 2004 and 2010: a cross-sectional study

BACKGROUND

Trans fatty acids (TFAs) produced from industrial partial hydrogenation of vegetable oils have been the subject of much research regarding their negative effect on the development of chronic diseases, and recommendations to label foods with partially hydrogenated vegetable oils and limit their levels were introduced in Canada in 2003 and 2007, respectively. Our aim was to determine temporal changes in circulating plasma TFAs in a population of young healthy Canadian adults after the introduction of the guidelines.

METHODS

In this study, circulating plasma concentrations and relative percent composition of individual TFAs over time (2004-2010) were determined in a cross-sectional cohort of young healthy Canadian adults as part of the Toronto Nutrigenomics study.

RESULTS

A total of 1294 participants were included in the cohort. Relative to 2004, total TFA levels were significantly lower in 2005-2009 (p < 0.05), but not in 2010. Although levels of 16:1t9 and 18:1t11 declined after 2004, levels of 18:1t9 and 18:1t10 were significantly lower in 2005-2009 (p < 0.05), but not in 2010.

INTERPRETATION

Trans fatty acids were lower in 2009 relative to 2004, but not different in 2010, suggesting that young Canadians may remain vulnerable to partially hydrogenated vegetable oil exposure and that there is a need for further monitoring of specific food categories and vulnerable populations.