Product Review

Vitamin C is a key compound in the body€s €œantioxidant network,€ a chain of synergistic, inextricability linked, well-studied antioxidants that includes glutathione (GSH) and vitamin E. When vitamin E uses its antioxidant function in neutralizing free radicals, it also loses this antioxidant function. Vitamin C can change this status; it can regenerate vitamin E back to its native form, and is thought to €œspare€ glutathione in the body as well. Importantly, when ascorbate donates an electron and becomes itself oxidized, or €œconsumed,€ the ascorbate radical is relatively harmless. In a double-blind, placebo-controlled study in which blood GSH was measured in healthy subjects at several stages, 500 mg of vitamin C taken daily for 2 weeks significantly raised erythrocyte (red blood cell) glutathione levels. The researchers concluded that vitamin C supplementation at that level can benefit the overall antioxidant capacity of the blood. In another study of similar design, 1000 mg of vitamin C taken daily for 4 weeks bolstered vitamin E and glutathione content in erythrocyte cell membranes, compared with placebo. The highest concentrations of vitamin C in the body are found in the central nervous system (in neurons of the brain & spinal cord) and the adrenal glands. Although the presence of ascorbate in neurons is in part explained by its neuromodulatory enzyme activity, its high concentration suggests that vitamin C is so greatly retained by neurons in order to address the higher rates of oxidative metabolism experienced by the brain. This has led to the conclusion that under normal conditions, vitamin C helps safeguard the integrity of neurons (and therefore the brain), largely through neutralization of the free radicals of reactive oxygen species (ROS). Low levels of blood vitamin C and the resulting accumulation of ROS are thought to be detrimental€"especially to aging populations.