Antioxidant micronutrient supplementation may be beneficial for critically ill patients. Often, cocktails of antioxidant micronutrients are used. Consequently, meta-analyses of available randomized controlled trials of antioxidant micronutrient supplementation are of particular interest. Because the majority of randomized controlled trials included in these meta-analyses use a combination of several antioxidant micronutrients, conclusions are difficult to draw. The scientific step to take now is to gain more knowledge about antioxidant mechanisms by coupling plasma concentrations to effects and outcomes.