Background: Neuroendocrine activation, activation of proinflammatory cytokines and platelets, and endothelial dysfunction play a significant role in the development of heart failure (HF).

Aim: The aim of the work was to assess the effect of supplementation with EPA and DHA in a daily dose of 1 g on selected inflammatory markers and platelet activation in patients with HF after recent myocardial infarction in light of their diet.

Methods: This preliminary study was a randomised, double-blind trial involving 30 patients with post-infarction HF. One group received a product containing 1 g of omega-3 acids, while the other received placebo, ie corn oil 1 g daily for 12 weeks. At baseline and at week 12, venous blood was obtained in the fasted state in order to determine the following parameters: NT-proBNP, fibrinogen, INR, creatinine clearance, serum lipid profile, hsCRP, troponin, glucose, transaminases, GGTP, MCP-1, pentraxin 3, and CD-40. To evaluate the patient’s diet and dietary intake of omega-3 acids, a 24-h dietary interview and the Block’s Food Frequency Questionnaire (FFQ) were applied.

Results: Supplementation of omega-3 acids in a dose of 1 g per day had no effect on lipid or inflammatory parameters, with the exception of pentraxin 3. In both groups, after three months of supplementation, overall consumption of energy and saturated fatty acids was significantly higher (p< 0.05).

Conclusions: Potential benefits associated with supplementation were nullified by a highly atherogenic diet. Apparently, supplementation of omega-3 acids without simultaneous dietary education and nutrition control does not bring the expected effect. Further research involving a larger group of patients is needed to better understand the relationship between patient’s diet and the effectiveness of omega-3 supplementation.