Rezaei and Hemilä1 raise interesting issues regarding the difference between vitamins E and C in their effect on contrast-induced acute kidney injury (CIAKI). They pooled results of 3 studies on vitamin E prophylaxis against CIAKI and calculated a pooled estimate of risk ratio (RR)=0.38 (95% CI, 0.24-0.62), indicating that vitamin E significantly prevented CIAKI. Therefore, they suggest an independent effect of vitamin E and argue that vitamin E and vitamin C should be analyzed separately.