Relationship between leucocyte and plasma ascorbic acid concentrations.

Leucocyte and plasma ascorbic acid values were measured in healthy students, adult factory employees, and old people not receiving supplementary vitamin C and in healthy old people receiving 500 mg of vitamin C daily. Significant positive correlations between leucocyte and plasma ascorbic acid were found in all the groups. The regression lines differed significantly between one another within the sexes, but the pooled lines for each sex did not differ significantly in the unsupplemented groups. The relationship between plasma and leucocyte ascorbic acid values in the supplemented group differed significantly from that in the pooled unsupplemented groups.There was a limited range of variation in leucocyte ascorbic acid values compared with the range in plasma values in the supplemented group, whereas there was a wider range of variation in the leucocyte values in the unsupplemented groups. Leucocytes can therefore achieve a saturation level of ascorbic acid. Measurement of leucocyte ascorbic acid concentrations alone does not provide a reliable guide for the estimation of tissue status of ascorbic acid in normal individuals. Leucocyte concentrations provide a measure of the availability of ascorbic acid for storage, and plasma levels give an indication of its metabolic turnover rate. When these values are related the regression lines provide information about the storage and metabolism of ascorbic acid in normal individuals.