Age-associated plasma lipids, lipid peroxidation, and antioxidant systems in relation to vitamin C supplementation in humans

It is hypothesized that a reduction in the level of ascorbic acid with age leads to an impairment in the quenching of free radicals by antioxidants, which in turn increases the risk of succumbing to age-associated disorders. Healthy volunteers of both sexes at different age group were selected from the geriatric community. They were subjected to vitamin C supplementation. Lipids, lipid peroxidation, enzymatic, and nonenzymatic antioxidant status were gauged at the end of 30, 60, and 90 days. The activities/levels of enzymatic and nonenzymatic antioxidants were found to be low in the aged humans, whereas the lipid peroxidation status was found to be high. Supplementation of vitamin C lowered the levels of lipid peroxides, cholesterol, triacylglycerol, and phospholipids and increased the activities of enzymatic antioxidants such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione-S-transferase in the geriatric population. A substantial rise in the levels of nonenzymatic antioxidants such as vitamins C, E, and A were also observed but no significant alterations were noticed in the levels of bilirubin and uric acid. From our observations, we conclude that ascorbic acid normalizes lipid peroxidation and partially restores the antioxidant status. Thus ascorbate supplementation could be beneficial in minimizing age-associated disorders where free radicals are the major cause.