Fig. 1. Steady-state plasma vitamin C concentrations (mean ± SD) as a function of dose for all doses for seven men. Subjects consumed a vitamin C deficient diet, resulting in plasma and tissue vitamin C depletion. Vitamin C in solution was then administered by mouth at the doses shown until steady state was reached for each dose. Doses through 400 mg daily were received by seven subjects, through 1000 mg daily by six subjects and through 2500 mg daily by three subjects. Reproduced with permission from Proceedings of The National Academy of Sciences, from which details of the study can be obtained [50].