Dugan, M. E. R., Aldai, N., Aalhus, J. L., Rolland, D. C. and Kramer, J. K. G. 2011. Review: Trans- forming beef to provide healthier fatty acid profiles. Can. J. Anim. Sci. 91: 545–556.Trans fatty acids are found naturally in foods, particularly in those derived from ruminant animals, such as beef and dairy cattle. Over the past few decades, human consumption of trans fatty acids has increased, but this has been mainly from products containing partially hydrogenated vegetable oils. The correlation of trans fatty acid consumption with diseases such as coronary heart disease has been cause for concern, and led to recommendations to reduce their consumption. Trans fatty acids, however, have differing effects on human health. Therefore, in foods produced from ruminant animals, it is important to know their trans fatty acid composition, and how to enrich or deplete fatty acids that have positive or negative health effects. This review will cover the analysis of trans fatty acids in beef, their origin, how to manipulate their concentrations, and give a brief overview of their health effects.