Effect of immunonutrition on serum levels of C-reactive protein and lymphocytes in patients with COVID-19: a randomized, controlled, double-blind clinical trial

Introduction: patients with COVID-19 undergo changes in leukocyte count, respiratory disorders, and an increase in inflammatory substances. To improve the inflammatory condition, some nutrients can be used, including arginine, omega-3 fatty acids and nucleotides. This study aims to evaluate how oral immunonutrient supplements affects serum C-reactive protein (CRP) levels and lymphocyte count in patients with COVID-19. Methods: in this double-blind clinical trial, we randomized 43 adult patients with COVID-19 to receive a standard high-protein normocaloric supplement (control) or an immunonutrient-enriched supplement (experiment) for 7 days. The primary outcome was to evaluate changes in total lymphocyte count and serum level of CRP. The assessment of risk and nutritional status of these patients was also performed. Results: forty-three patients with mean age of 41.5 (± 1.8) years were followed up, 39.5 % of them women. The mean body mass index was 27.6 (± 0.8) kg/m² and 58.1 % had low nutritional risk. In the experiment group, there was a CRP reduction of 23.6 (± 7.5) mg/L, while in the control branch the decrease was 14.8 (± 12.1) mg/L (p = 0.002). There was an increase in lymphocytes in the experiment group (+367.5 ± 401.8 cells/mm³) and a reduction in the control group (-282.8 ± 327.8 cells/mm³), although there was no statistical significance (p = 0.369). Relative risk (RR) of treatment in reducing CRP by 30 % or more was 4.45 (p < 0.001; 95 % CI, 1.79-11.07). RR in increasing lymphocyte count by 30 % or more was 1.28 (p = 0.327; 95 % CI, 0.67-2.45). Conclusion: we conclude that immunonutrient supplements seem to reduce CRP levels more than standard high-protein normocaloric supplements.