The objective of this study was to evaluate potential anti-atherogenic properties of hen eggs enriched naturally with conjugated linoleic acid (CLA) isomers (cis-9, trans-11 and trans-10, cis-12). Eighteen apoE and LDL receptor double-knockout mice (apoE/LDLR 2/2 ), at the age of 4 months with pre-established atherosclerosis, were randomly assigned to three experimental groups (n 6) and fed AIN-93G-based diets for the next 2 months. The experimental diets were: AIN-93G þ CLA-free egg-yolk powder (control); AIN-93G þ CLA-free egg-yolk powder þ 0·1 % CLA (CLA-supplemented eggs); and AIN-93G þ CLA-enriched egg-yolk powder, providing 0·1 % CLA (CLA-enriched eggs). For assessment of anti-atherogenic properties of CLA-enriched or CLA-supplemented eggs the following criteria were used: (1) serum lipid profile; (2) development of atherosclerosis; and (3) composition of atherosclerotic plaque. CLA-enriched eggs, compared with CLA-supplemented eggs, reduced significantly (P,0·05) total plasma cholesterol in the mice. At the same time, both CLA-supplemented eggs and CLA-enriched eggs tended to decrease the size of atherosclerotic plaque in aortic roots of mice. Most importantly, atherosclerotic plaques of mice fed CLA-enriched eggs showed significantly (P, 0·05) reduced number of atherogenic macrophages and increased area occupied by smooth muscle cells in atherosclerotic lesions. In conclusion, CLA-enriched eggs exerted an anti-inflammatory effect more effectively than CLA-supplemented eggs. This anti-inflammatory effect can be considered their major functional claim that warrants further exploitation. Conjugated linoleic acid: apoE/LDLR 2/2 : Atherosclerosis: Composition of aortic plaque Conjugated linoleic acid (CLA) is a collective term to describe a class of positional and geometric isomers of linoleic acid (cis-9, cis-12 C18 : 2n-6) in which the two double bonds are separated by a single C-C bond, but not by a methylene group (-CH 2 -). CLA isomers are intermediate products of bacterial biohydrogenation of dietary unsaturated fatty acids in the rumen, and are mainly found in fat of ruminant milk and meat 1 .In the last 10 years, extensive research have indicated that commercial CLA preparations, fed to laboratory animals, showed several health-related properties, including antiadipogenic 2 -5 , anti-carcinogenic 6 -8 , anti-atherogenic 9 -15 and anti-inflammatory 16,17 effects. Consequently, in view of the evident health-related properties associated with CLA isomers and also in line with the concept of functional foods 18 , attempts have been made to enrich animal-derived foods with CLA isomers through animal nutrition strategies. Indeed, these attempts resulted in production of functional food such as CLA-enriched milk (butter, cheese), ruminant and non-ruminant meat, as well as eggs 19,20 -23 .Except for our preliminary studies 24 , there have been no data available on whether eggs, enriched naturally with CLA isomers, and fed to laboratory animals, could have healthrelated properties similar to those described f...
