Vitamin C (ascorbate) — The Essential Water-Soluble Antioxidant
Vitamin C, or ascorbic acid, is a vital water-soluble antioxidant and enzymatic cofactor essential for collagen synthesis, immune function, and neutralizing reactive oxygen species. While not traditionally viewed as a direct lifespan-extending molecule, its role in mitigating oxidative stress and supporting vascular health makes it a foundational component of healthspan maintenance.
Mechanism of Action
Vitamin C acts as a primary electron donor, neutralizing free radicals such as superoxide and hydroxyl radicals, thereby protecting cellular structures from oxidative damage. It is an essential cofactor for prolyl and lysyl hydroxylases, enzymes required for the stabilization and cross-linking of collagen fibers. Additionally, ascorbate recycles other antioxidants, notably vitamin E, back to their active states. Emerging evidence suggests it may also influence epigenetic regulation by acting as a cofactor for TET (Ten-Eleven Translocation) dioxygenases, which are involved in DNA demethylation.
Human Trial Evidence
Extensive human trials have investigated Vitamin C for cardiovascular health, immune support, and cancer. While high-dose intravenous Vitamin C has shown some adjunctive benefits in specific oncology settings, large-scale oral supplementation trials have generally failed to demonstrate significant extensions in overall lifespan or major reductions in all-cause mortality in well-nourished populations. Its primary proven benefits relate to preventing deficiency and modestly reducing the duration of upper respiratory tract infections.
Dosing Protocol
Typical oral dosing ranges from 500 to 1,000 mg per day, often divided to maximize absorption, as intestinal transport becomes saturated at higher doses. Liposomal formulations are sometimes used to improve bioavailability. High-dose intravenous protocols (e.g., 10–50 grams) are used in clinical settings for specific indications but are not standard for general longevity.
Safety & Contraindications
Generally recognized as safe with a low toxicity profile due to its water-soluble nature. High oral doses (typically >2,000 mg/day) can cause gastrointestinal distress, including diarrhea and nausea. It may increase the risk of oxalate kidney stones in susceptible individuals. High-dose supplementation should be avoided in patients with hemochromatosis or other iron-overload disorders, as Vitamin C enhances non-heme iron absorption.