Handbook of Vitamin C Research

C mgC mgC mgC mg62Yasuo Kagawa, Shizu Higasa, Masaru Tsujimura et al.Figure 3 indicates the large interindividual differences in the time course of VC excretionamong four subjects in group B loaded with AsA (1 m mole) and DAsA (1m mole) under thesame condition described in Figure 1. The cause of interindividual difference will bediscussed in the following section.Subject BSubject DSubject BSubject D403020403020100Subject G-12~0 0~3 3~6 6~9 9~12 12~24Time(h)100Subject L-12~0 0~3 3~6 6~9 9~12 12~24Time(h)Subject GSubject L40403030202010Figure 3. Figure Interindividual 0 3 difference in the quantities and time course 0 of VC excretion of four subjectsafter loading AsA -12~0 and DAsA 0~3 under 3~6 the 6~9 condition 9~12 12~24 described in Figure -12~0 1. [31].0~3 3~6 6~9 9~12 12~24Time(h)Time(h)Discussion(1) Human Specific VC Metabolism and Antioxidant Activity of VCVC differs from other vitamins in that an exogenous source is required only by few VCauxotrophs including humans [1, 26, 27], while in all animals VC acts as an antioxidant [1,11] and a cofactor in the biosynthesis of collagen and catecholamine [1]. VC autotrophs suchas rat synthesize VC at the rate of 58mg/day/kg body weight [30] (average VC half life: 2.9days), while VC auxotrophs including humans consume VC about 2 mg/day/kg body weight(Tables 2 and 3), and less than 1 mg/day/kg in the case of Mongolians (Table 1) (average VChalf life: 16 days (7.5 -18.5 days) [42]). To prevent scurvy in humans 10mg/day or0.2mg/day/kg body weight is enough [28]. Moreover, VC autotrophs increase VC synthesisseveral fold in the presence of xenobiotics such as aminopyrine and chloretone [1] or under10