Plasma hydroperoxides are inversely related to vitamin C status in healthy adults

Plasma hydroperoxides are a marker for tree radical and peroxidation activity in blood. We examined the relationship between vitamin C status and plasma hydroperoxide levels in healthy adults. Hydroperoxides were measured by the in vitro oxidation of ferrous to ferric ions utilizing the indicator dye xylenol orange. Non-smoking subjects (n=99; 74 females and 24 males) were recruited from a campus population. Ages ranged from 18-40 years (mean=23.1±5.8 years). The mean fasting plasma vitamin C level for all subjects was 0.73±0.23 mg/dL (acceptable range: 0.6-0.8 mg/dL). Plasma vitamin C values were inversely correlated with plasma hydroperoxide values (r=0.20, p<0.05). Vitamin C depleted subjects (n=20, plasma vitamin C <0.55 mg/dL) had an increased plasma hydroperoxide load compared to subjects with adequate vitamin C status (n=79, plasma vitamin C ≥0.55 mg/dL), 3.99±1.73 μM and 3.27±1.39 μM. respectively (p<0.05). These data provide further evidence that vitamin C status is associated with improved antioxidant defense in plasma.