Vitamin C (ascorbic acid) is an essential water-soluble vitamin and potent antioxidant that humans cannot synthesise endogenously due to the absence of the enzyme L-gulonolactone oxidase. It must therefore be obtained entirely through dietary intake or supplementation. As one of the most extensively studied micronutrients in clinical nutrition, Vitamin C plays a central role in numerous physiological processes, from immune defence and collagen biosynthesis to neurotransmitter synthesis and iron absorption.
Biochemistry and Mechanisms of Action
Ascorbic acid functions primarily as an electron donor, making it one of the body's most important water-soluble antioxidants. It neutralises reactive oxygen species (ROS) and reactive nitrogen species (RNS), protecting cellular structures from oxidative damage. It also regenerates other antioxidants, including vitamin E (tocopherol), back to their active forms.
Key biochemical roles include:
- Collagen synthesis: Vitamin C is an essential cofactor for prolyl and lysyl hydroxylases, enzymes required for the hydroxylation of proline and lysine residues in procollagen — a critical step in forming stable collagen triple helices.
- Carnitine biosynthesis: Required for the synthesis of L-carnitine, which facilitates fatty acid transport into mitochondria for beta-oxidation.
- Neurotransmitter synthesis: Acts as a cofactor in the conversion of dopamine to norepinephrine via dopamine beta-hydroxylase.
- Iron absorption: Reduces dietary non-haem iron (Fe³⁺) to the more bioavailable ferrous form (Fe²⁺), significantly enhancing intestinal absorption.
Immune Function
Vitamin C accumulates in high concentrations within immune cells, particularly neutrophils, lymphocytes, and monocytes, where it supports multiple aspects of immune defence:
- Stimulates the production and function of leukocytes, including neutrophils and natural killer (NK) cells
- Enhances chemotaxis, phagocytosis, and oxidant generation in neutrophils
- Supports epithelial barrier integrity, the body's first line of defence against pathogens
- Promotes antibody production and T-lymphocyte differentiation
A 2013 Cochrane review (Hemilä & Chalker) found that regular Vitamin C supplementation (≥200 mg/day) reduced the duration of common cold symptoms by 8% in adults and 14% in children, with greater effects observed in individuals under physical stress.
Antioxidant and Anti-inflammatory Effects
Chronic low-grade inflammation underlies many non-communicable diseases, including cardiovascular disease, type 2 diabetes, and certain cancers. Vitamin C's antioxidant capacity helps mitigate oxidative stress — a key driver of inflammatory cascades. Epidemiological studies consistently associate higher plasma ascorbate levels with lower markers of systemic inflammation, including C-reactive protein (CRP) and interleukin-6 (IL-6).
Cardiovascular Health
Vitamin C supports endothelial function by promoting nitric oxide (NO) bioavailability, which facilitates vasodilation and reduces arterial stiffness. Meta-analyses have demonstrated that supplementation is associated with modest reductions in systolic and diastolic blood pressure. Additionally, its role in preventing LDL oxidation may contribute to reduced atherosclerotic plaque formation.
Skin Health
Given its central role in collagen synthesis and antioxidant defence, Vitamin C is critical for skin integrity and repair. Adequate intake supports dermal collagen density, reduces UV-induced oxidative damage, and may attenuate photoageing.
Deficiency and Scurvy
Clinical deficiency (plasma ascorbate <11 µmol/L) manifests as scurvy after approximately 4–6 weeks of negligible intake. Early symptoms include fatigue, irritability, and joint pain, progressing to perifollicular haemorrhages, gingival disease, impaired wound healing, and anaemia. Risk groups include smokers, individuals with limited dietary variety, those with malabsorption conditions, and the elderly.
Supplementation Guidelines
- Recommended Dietary Intake (RDI): 45 mg/day (Australia/NZ); 75–90 mg/day (US RDA)
- Therapeutic range: 500–2,000 mg/day for immune support and antioxidant benefit
- Smokers: Require an additional 35 mg/day above standard recommendations
- Upper tolerable intake: 2,000 mg/day
- Form: Ascorbic acid is the most cost-effective form; buffered forms may be better tolerated gastrointestinally at higher doses; liposomal Vitamin C offers enhanced bioavailability
Our Recommended Vitamin C Supplements
At The Wellness Store, we stock a comprehensive range of practitioner-quality Vitamin C formulations:
- Liposomal Vitamin C — superior bioavailability via phospholipid encapsulation for maximum absorption
- LivOn Lypo-Spheric Vitamin C — a gold-standard liposomal formulation in convenient sachets
- Buffered Vitamin C — gentle on the stomach, ideal for higher therapeutic doses
- Buffered Vitamin C Powder — flexible dosing in powder form
- LightHouse Lypo-Caps Vitamin C — liposomal capsules for convenient daily use
- Quicksilver Scientific Vitamin C + Elderberry — combines high-potency Vitamin C with immune-supporting elderberry
- Vitamin C + R-Lipoic Acid — pairs Vitamin C with R-Lipoic Acid for enhanced antioxidant synergy
Dietary Sources
- Kiwifruit — ~93 mg per fruit (one of the richest sources)
- Red capsicum — ~190 mg per 100g
- Citrus fruits — 50–70 mg per 100g
- Broccoli — ~89 mg per 100g (raw)
- Strawberries — ~59 mg per 100g
Note: Vitamin C is heat-labile and water-soluble; cooking significantly reduces content in foods.
Conclusion
Vitamin C remains one of the most clinically relevant and evidence-supported micronutrients in integrative and preventive medicine. Its roles in immune modulation, collagen synthesis, antioxidant defence, and cardiovascular health make it a foundational supplement for overall wellbeing. At The Wellness Store, we stock practitioner-quality Vitamin C formulations to suit a range of clinical needs and tolerances.
This article is for educational purposes only and does not constitute medical advice. Please consult your healthcare provider before commencing supplementation.