The beneficial effects of antioxidant supplementation in enteral feeding in critically ill patients: a prospective, randomized, double-blind, placebo-controlled trial

Weinvestigated whether intervention with antioxidant vitamins C and E in enteral feeding influenced oxidative stress and clinical outcome in critically ill patients. Two-hundred-sixteen patients expected to require at least 10 days of enteral feeding completed the study. One-hundred-five patients received enteral feeding supplemented with antioxidants, and 111 control patients received an isocaloric formula. Plasma lipoperoxidation (by thiobarbituric acid reactive substances [TBARS] and prostaglandin F2* isoprostane levels), low-density lipoprotein (LDL) oxidizability, and LDL tocopherol content were determined at baseline and at the end of the 10-day period. The clinical 28-day outcome was also assessed. Plasma TBARS and isoprostanes were 5.33 * 1.26 nM/mL and 312 * 68 pg/mL, respectively, before treatment and 2.42 * 0.61 nM/mL and 198 * 42 pg/mL after intervention (P * 0.01 for both comparisons). Antioxidants improved LDL resistance to oxidative stress by approximately 30% (the lag time before treatment was 87*23 min and was 118*20 min after treatment; P*0.04). There was a significantly reduced 28-day mortality after antioxidant intervention (45.7% in the antioxidant group and 67.5% in the regular-feeding group; P * 0.05). Isoprostanes may provide a sensitive biochemical marker for dose selection in studies involving antioxidants.