WHAT VITAMIN C DOES IN THE BODY
– Vitamin C (ascorbic acid) is a powerful antioxidant that protects cells from free radical damage.
– It donates electrons to neutralize reactive oxygen species (ROS).
– After oxidation, it can be recycled back into active vitamin C using enzymes and glutathione.
ENZYME COFACTOR AND METAL ION REGULATION
– Acts as a cofactor for many enzymes.
– Keeps iron and copper in active forms (Fe3+ → Fe2+ and Cu2+ → Cu+).
– Supports DNA synthesis, epigenetic regulation, and neurotransmitter production.
COLLAGEN AND CONNECTIVE TISSUE HEALTH
– Required for hydroxylation of proline and lysine in collagen synthesis.
– Maintains strong blood vessels, skin, and connective tissues.
– Deficiency leads to weak vessels, poor healing, and scurvy.
OXYGEN SENSING AND CELL METABOLISM
– Required for hydroxylase enzymes regulating HIF‑1 (hypoxia‑inducible factor‑1).
– Controls cell response to low oxygen, glucose metabolism, and angiogenesis.
– Low vitamin C stabilizes HIF‑1, promoting abnormal metabolism and tumor growth.
EPIDEMIOLOGICAL FINDINGS
– Low vitamin C levels linked to higher cancer risk, cardiovascular disease, and mortality.
PRO‑OXIDANT EFFECT AT HIGH DOSES
– At pharmacological levels, vitamin C becomes pro‑oxidant.
– Generates hydrogen peroxide (H2O2) in the presence of iron.
– Causes oxidative stress, DNA damage, and protein oxidation.
SELECTIVE TOXICITY TO CANCER CELLS
– Cancer cells contain more iron and weaker antioxidant systems.
– They cannot detoxify H2O2 efficiently.
– Leads to oxidative damage, autophagy, apoptosis, and necrosis.
IN‑VITRO EVIDENCE
– Sensitive cancer cell lines include pancreatic, cervical, colon, breast, and prostate cancers.
– Chen et al. (2012): 5 of 6 prostate cancer lines sensitive to millimolar ascorbate.
– Cell death mediated by extracellular H2O2.
IN‑VIVO ANIMAL STUDIES
– Oral vitamin C only achieves normal blood levels.
– IV or injection reaches pharmacological levels (~20 mM).
– In mice, high‑dose vitamin C inhibited tumor growth and caused tumor necrosis.
KEY CONCLUSIONS
– Vitamin C is essential for antioxidant defense, collagen synthesis, enzyme activity, iron
metabolism, and gene regulation.
– High‑dose vitamin C selectively damages cancer cells through oxidative stress.
– Effects depend on dose, administration route, and tumor vulnerability.