Impact of a Dietary Fish Oil Supplementation on the Plasma Lipidome of Healthy Adult Cats

Background/Objectives: Dietary fish oil supplementation has been associated with lower total plasma triacylglycerols in felines. The present study aimed to characterize this effect in more detail, using lipidomic analyses. Methods: Plasma samples of cats (n = 10), receiving a complete basic diet, with and without the addition of 0.5 g and 1.0 g fish oil/kg body weight/day, each for 21 days, in a randomized crossover design, were analyzed by an FIA MS/MS-based targeted metabolomics approach. Results: The results demonstrated that 360 metabolites were affected by the dietary treatments, predominantly belonging to triacylglycerols (n = 124), phosphatidylcholines (n = 68), phosphatidylethanolamines (n = 63), phosphatidylglycerols (n = 33), and phosphatidylinositols (n = 21). Lowering effects of fish oil supplementation on plasma triacylglycerols could be confirmed. However, increased levels of specific triacylglycerols were also observed, especially of those containing eicosapentaenoic or docosahexaenoic acid. The decreased triacylglycerols showed a lower number of carbons and a lower degree of unsaturation than the enhanced triacylglycerols. Such a lipid profile is assumed to be beneficial in human medicine; its relevance for feline health, however, is unclear so far. Conclusions: In conclusion, the lipidomic analyses provided a detailed characterization of the feline plasma lipidome and its modulation by a dietary fish oil supplementation. The clinical relevance of these findings warrants further investigation.