Kinetic parameters were estimated in nonsmokers and smokers to help elucidate the quantitative ascorbate metabolism in humans. This approach allows calculation of turnover rates at different levels of steady state intakes of ascorbate. Metabolic and renal turnovers were calculated separately. At plasma levels above about 0.7 mg/100 mL the renal elimination increased sharply and the metabolic turnover showed a saturation at a plasma level corresponding to a total turnover of about 60 mg/d. At the tested levels of intake of ascorbic acid the calculated total pool size increased to a level reached at a steady state plasma concentration achieved at an intake of about 90 mg/d. At intakes of this magnitude the absorption is substantially less than 100%. A daily intake of 100 mg of ascorbate for larger populations should be attained. Similar experiments with smokers showed an increase in the metabolic turnover corresponding to a demand of 140 mg/d to reach a similar stage.