Acute post-ingestion changes in plasma ascorbic acid concentration: Relationship to dose and to existing body stores.

Plasma ascorbic acid concentrations were measured in 27 adults before and after ingestion of 0.5 - 3.0 g of vitamin C. Mean (SEM) fasting concentration was 64 (3) mu mol/l, with no significant male-female difference. There was a significant correlation between the response and log dose (r = 0.928; P <0.01). There was no significant correlation (r = 0.14; P >0.1) between the dose-corrected increase and the fasting concentration; 0.5 g caused a greater increase than 0.25 g (mean increases 56 and 33 mu mol/l respectively; P <0.01); doses of 1.0 g and 2.0 g did not cause significantly greater responses. Results indicate that i) response to ingestion of vitamin C is dose dependent and independent of body stores of the vitamin, ii) a 0.5g dose appears optimal in terms of increasing the plasma ascorbic acid concentration. Copyright (C) 1997 Elsevier Science Inc.