Handbook of Vitamin C Research

Human Specific Vitamin C Metabolism… 59genotype (0.89 mg/dL) was only 17%, while the difference in VC concentrations before andafter VC loading was 16 - 27%. This indicates that the change in VC excretion (7-11-fold) ismore sensitive than serum VC concentrations in reflecting VC load. Table 3C summarizes thecorrelation coefficients between 3-h blood VC levels and total amounts of VC excretedduring the 24-h period after loading with 1 mmol of AsA or DAsA. When AsA and DAsAare combined, the correlation is significant. Owing to small sample numbers, othercorrelation coefficients did not reach significance.Table 3. Total Vitamin C concentrations in whole blood before and after loadingwith 1 mmol AsA or DAsA in glutathione S-transferase P1 AA homozygotes and GAheterozygotesTotal vitamin C concentrations in bloodA. Before VC loadingVitamin CAsA+DAsAAsADAsAB. 1 h after loading (1 mmol VC)Loaded VCAsA+DAsAAsADAsABlood VC AA: homozygotes, GA: heterozygotes Significancemg/dL AA+GA (17) AA (12) GA (5) AA vs. GAaverage 0.82±0.12 0.84±0.12 0.77±0.12 n.s.maximum 1.07 1.07 1.03minimum 0.59 0.59 0.59average 0.82±0.14 0.84±0.12 0.78±0.17 n.s.maximum 1.07 1.07 1.03minimum 0.59 0.59 0.59average 0.81±0.11 0.83±0.11 0.76±0.06 n.s.maximum 1.07 1.07 0.83minimum 0.61 0.61 0.66Blood VC AA: homozygote, GA: heterozygote Significancemg/dL AA + GA(17) AA (12) GA (5) AA vs. GAaverage 1.01 ± 0.17 1.07 ± 0.15 0.89 ± 0.15 p < 0.0036maximum 1.34 1.34 1.07minimum 0.59 0.73 0.59average 0.94 ± 0.14 0.98 ± 0.12 0.86 ± 0.18 n.s.maximum 1.13 1.13 1.05minimum 0.59 0.73 0.59average 1.09 ± 0.16 1.16 ± 0.12 0.92 ± 0.14 p < 0.0030maximum 1.34 1.34 1.07minimum 0.79 0.96 0.79C. Correlation between blood VC (3 h) and urine VC (24 h)AA+GA(17) AA (12) GA (5) AA vs. GAAsA+DAsA significance0.609 p < 0.001 0.553 p < 0.01 0.722 p < 0.05 n.s.AsA significance 0.662 p < 0.01 0.547 n.s. 0.877 n.s. n.s.DAsA significance 0.582 p < 0.05 0.610 p < 0.05 0.522 n.s. n.s.Values are means ± SD. There were no GG homozygous subjects.