Effect of enteral feeding with eicosapentaenoic acid, γ-linolenic acid, and antioxidants on antioxidant status in patients with acute respiratory distress syndrome

Background: We previously showed that enteral feeding of a diet containing eicosapentaenoic acid, γ-linolenic acid, and elevated antioxidants improved clinical outcomes compared with a control diet in acute respiratory distress syndrome (ARDS) patients. It has been suggested that oxidative stress may overwhelm endogenous antioxidant levels and allow free radicals to further damage lung tissue. Therefore, we determined whether these ARDS patients were under oxidative stress and whether the experimental diet could improve antioxidant status. Methods: Ninety-eight ARDS patients received either the experimental or control diet (minimum of 75% of basal energy expenditure × 1.3) for at least 4 to 7 days. Total radical antioxidant potential (TRAP), lipid peroxide levels (LPO), and plasma antioxidant concentrations were determined at baseline and study days 4 and 7. Sixty-two normal individuals were assessed for reference values. Results: At baseline, ARDS patients had significantly lower plasma β-carotene, retinol, and α-tocopherol, lower TRAP, and higher LPO values compared with normals. After 4 days of feeding, β-carotene and α-tocopherol levels were normalized and significantly increased in the experimental group compared with controls. TRAP and LPO were not significantly different between groups and study day 4 and 7 values were not different from baseline values. Retinol levels increased equally in both groups. Conclusions: Before treatment, ARDS patients were found to be in a state of oxidative stress and had reduced levels of antioxidants. Although enteral nutrition with the experimental diet for at least 4 to 7 days did not reduce oxidative stress as measured, it did restore plasma levels of β-carotene and α-tocopherol to normal or higher levels and appeared to protect ARDS patients from further lipid peroxidation.