Antioxidant micronutrients in the critically ill: a systematic review and meta-analysis

Critical Care, 04/26/2012

Manzanares W et al. – Supplementation with high dose trace elements and vitamins may improve outcomes of critically ill patients, particularly those at high risk of death.


  • The authors searched computerized databases, reference lists of pertinent articles, and personal files from 1980 to 2011.
  • They included randomized controlled trials (RCTs) conducted in critically ill adults patients that evaluated relevant clinical outcomes with antioxidants micronutrients (vitamins and trace elements) supplementation versus placebo.


  • A total of 21 RCTs met inclusion criteria.
  • When the results of these studies were statistically aggregated (n=20), combined antioxidants were associated with a significant reduction in mortality (risk ratio [RR]=0.82, 95% confidence interval [CI] 0.72-0.93, P=0.002); a significant reduction in duration of mechanical ventilation (weighed mean difference in days=-0.67, 95% CI -1.22,-0.13, P=0.02); a trend towards a reduction in infections (RR=0.88, 95% CI 0.76,1.02, P=0.08); and no overall effect on ICU or hospital length of stay (LOS).
  • Furthermore, antioxidants were associated with a significant reduction in overall mortality among patients with higher risk of death (>10% mortality in control group) (RR 0.79, 95 % CI 0.68, 0.92, P=0.003) whereas there was no significant effect observed for trials of patients with a lower mortality in the control group (RR=1.14, 95% 0.72, 1.82, P=0.57).
  • Trials using more than 500g per day of selenium showed a trend towards a lower mortality (RR=0.80, 95% CI 0.63-1.02, P=0.07) whereas trials using doses lower than 500g had no effect on mortality (RR 0.94, 95% CI 0.67-1.33, P=0.75).

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