Plasma ascorbic acid in adult males: effects of depletion and supplementation.

We investigated effects of moderately elevated oral doses of ascorbic acid (AS) on plasma AS turnover in healthy men after abrupt alterations in AS intake. Subjects ate a basal diet of conventional food in which only AS intake was changed. Blood specimens were collected from fasted subjects twice each week during depletion periods. Deproteinized plasma was analyzed after derivatization with 2,4-dinitrophenylhydrazine. Subjects remained healthy and never became frankly scorbutic. The kinetics of log-converted plasma AS values for the depletion periods demonstrated that the slopes calculated by least squares were up to 56% higher for six of nine subjects after 600 mg AS/day. The difference between the mean slopes (M) for loss of plasma AS was significantly different (p less than 0.05, n = 6) after 60 mg AS (M = -0.0222 +/- 0.0145) than after 600 mg AS (M = -0.0246 +/- 0.0003). Leukocyte AS concentration decreased 44.6% in the first depletion period and 77.1% in the second.