Vitamin C — Supplements
Essential water-soluble antioxidant and enzyme cofactor supporting immune function and collagen synthesis.
Overview
Vitamin C (ascorbic acid) is an essential water-soluble vitamin that functions as a potent antioxidant, enzyme cofactor for collagen synthesis (prolyl and lysyl hydroxylases), and immune system modulator. Humans lack the enzyme L-gulonolactone oxidase required for endogenous synthesis. Vitamin C concentrates in immune cells at 10-100 times plasma levels and is rapidly consumed during infections. Meta-analyses of >30 RCTs show consistent reduction in cold duration (8% in adults, 14% in children) with regular supplementation, though not in cold incidence. Strong evidence supports its role in iron absorption enhancement and wound healing.
Indications
- Immune function support
- Collagen synthesis and wound healing
- Iron absorption enhancement
- Antioxidant defense
- Common cold duration reduction
Mechanism of Action
Ascorbate donates electrons to neutralize reactive oxygen species, protecting cells from oxidative damage
Dosing
| Compound | Dose | Frequency | Notes |
|---|---|---|---|
| Vitamin C | 1,000 mg | Once daily | Divided doses may improve absorption; take with iron-containing foods if addressing iron deficiency |
Safety & Contraindications
- GI distress (diarrhea, cramping) at doses >2,000 mg/day in sensitive individuals
- May increase oxalate excretion; caution in history of calcium oxalate kidney stones
- High doses may interfere with certain lab tests (glucose, occult blood)
- Excessive supplementation in iron overload conditions is contraindicated