Frei et al's 2012 review entitled "Authors' Perspective: What is the Optimum Intake of Vitamin C in Humans" is both flawed and misleading. RCTs are ill suited to determining the RDA, it is debatable that there is sufficient scientific evidence to determine the optimum intake of vitamin C in humans, observations regarding high-doses of ascorbate have been ignored, and there are inaccuracies of fact with respect to the saturation of blood plasma following low dose intake. Until the limitations of current knowledge are recognised it is unwise to set limits on the dose.