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diabetes [8], atherosclerosis [9], the common cold [10], cataracts [11], glaucoma [12], macular degeneration [13], stroke [14], heart disease [15], COVID-19 [16], and cancer.

1–5% of the Vit-C inside the human cells

interaction between Fe(II) and H2O2 produces OH− through the Fenton reaction

iron and ascorbate has long been used as an oxidizing system; the combination of these two reagents is referred to as the Udenfriend system

ascorbate serves as a reducing cofactor for many enzymes

uptake of ascorbate from the intestinal tract is very tightly controlled

It is well known that vitamin C, or ascorbic acid, is an effective biologic antioxidant and does not act as a pro-oxidant under normal conditions (5) because it does not readily autoxidize, i.e., react with oxygen (O2) to produce reactive oxygen species, such as superoxide radicals (O2•−) or H2O2

However, ascorbate readily donates an electron to redox-active transition metal ions, such as cupric (Cu2+) or ferric (Fe3+) ions, reducing them to cuprous (Cu+) and ferrous (Fe2+) ions, respectively

Reduced transition metal ions, in contrast to ascorbic acid, readily react with O2, reducing it to superoxide radicals (Reaction 2), which in turn dismutate to form H2O2 and O2

Hydroxyl radicals cause oxidative damage to cells because they unspecifically attack biomolecules [22] located less than a few nanometres from its site of generation and are involved in cellular disorders such as neurodegeneration [23, 24], cardiovascular disease [25], and cancer [26, 27].

It is generally assumed that in biological systems is formed through redox cycling by Fenton reaction, where free iron (Fe2+) reacts with hydrogen peroxide (H2O2) and the Haber-Weiss reaction that results in the production of Fe2+ when superoxide reacts with ferric iron (Fe3+)

other transition-metal including Cu, Ni, Co, and V can be responsible for formation in living cells

Anemia is a frequent finding in cancer patients, occurring in >40% of cases

chemotherapy, the incidence of anemia may rise to 90%

Anemia exerts a negative influence on the quality of life

Inflammation is the most predominant feature during the early (relaping) phases of the disease and declines with aging of the patients and disease duration

in the process of oligodendrocyte destruction and demyelination in MS lesions iron is liberated from its intracellular ferritin bound stores into the extracellular space, where it is taken up by microglia and macrophages and again stored together with ferritin. When this happens in MS lesions in an environment, where free radicals are produced by oxidative burst, iron can be liberated from ferritin and transformed into reactive Fe++[114], which reacts with hydrogen peroxide to generate highly reactive hydroxyl radicals [36] and thus amplifies oxidative damage and associated cellular injury

anti-inflammatory or immunomodulatory treatments are effective in the relapsing stage, but the benefit is lost when the patients have entered the progressive phase