Enhancing Rats’ Diet with Ethyl Esters Derived from Linseed Oil and Examining the Resulting Changes in Their Blood Fatty Acid Profile

Omega-3 fatty acids are an important factor contributing to the prevention and cure of numerous diseases, and therefore their supplementation with diet is a significant issue. There are numerous supplements on the market containing omega-3 acids, of both plant and animal origin. In our study, we compared an effect of linseed oil, ethyl esters of linseed oil and fish oil supplementation to rats’ diet on their blood serum and erythrocyte fatty acid profile. The animals were divided into nine groups, three groups did not receive supplements and differed in dietary fat content, three were fed a high-fat diet for the whole experiment and supplemented, three were fed a high-fat diet and then the control one together with supplements. The experiment lasted 12 weeks. Significant changes in the profile of omega-3 fatty acids, as well as the ration of omega-6 to omega-3, were found in supplemented groups compared to the controls, the changes were more beneficial in groups supplemented with ethyl esters of linseed oil. The results were also more beneficial in groups where in addition to supplementation, there was also a dietary change from high fat to control during the supplementation period. In the case of the erythrocytes, the alpha-linolenic acid (ALA) content in ethyl ester-supplemented groups increased (p < 0.05) by about 60–120%, eicosapentaenoic acid (EPA) by 80%, and docosahexaenoic acid (DHA) by 41–60% compared to the control. In turn, in the blood serum, this increase (p < 0.05) was about 70–125%, 26–40%, and 38–54%, respectively. In the case of ethyl esters, except for an increase in EPA and DHA acids, higher values of ALA were found, which can be further used in the process of conversion to longer-chain omega-3.