Vitamin C (ascorbic acid)
Foundational nutrient with multiple EFSA-authorised claims and the Cochrane signal for shorter common-cold duration.
Why
Vitamin C (L-ascorbic acid) is a water-soluble essential nutrient with multiple EFSA-authorised health claims covering immune function, oxidative-stress protection, collagen formation, normal psychological function, energy-yielding metabolism, and increased iron absorption from plant sources. The Cochrane review of vitamin C for the common cold (Hemilä 2013) found that routine prophylaxis at ≥200 mg/day reduces common cold duration by ~8% in adults and ~14% in children, and reduces incidence specifically in those undergoing heavy physical stress (marathon runners, soldiers).
How it works
Cofactor for collagen prolyl and lysyl hydroxylases (vessel wall, skin, bone). Cofactor for dopamine β-hydroxylase and tyrosine hydroxylase (catecholamine synthesis). Reduces oxidised vitamin E and glutathione (recycles the antioxidant network). Reduces dietary iron to the absorbable ferrous form.
Expected onset · Symptomatic effects on cold duration require ongoing prophylactic intake; acute rescue dosing modestly reduces severity
How to take
Dosage
Daily: 75–90 mg (RDI). Common cold prophylaxis: 200 mg/day. Common cold rescue: starting at symptom onset, 1–2 g/day divided. Iron absorption: 100 mg with iron-containing meal.
Timing
With meals; divided for higher doses (absorption saturates above 200 mg per dose)
On the label
L-ascorbic acid (basic form), sodium ascorbate (buffered, gentler on GI), or liposomal forms (claims of better absorption, modest at best).
Ideal for
Adults seeking immune support during high-exposure seasons; people with low dietary fruit and vegetable intake; vegetarians/vegans needing enhanced non-haem iron absorption; people under heavy physical stress.
Safety
Evidence
EFSA-authorised health claims cover six separate functions, among the most-anchored nutrients in EU food law. Cochrane 2013 SR on common cold prophylaxis (29 RCTs, n>11,000): regular intake reduced cold duration by ~8% in adults, ~14% in children. Effect on incidence is restricted to high-physical-stress contexts. Treatment-dose rescue evidence is weaker.
- Hemilä & Chalker, Cochrane Database Syst Rev 2013, vitamin C for preventing and treating the common cold
- EFSA Reg 432/2012 authorised claims, vitamin C and immune function, collagen, iron absorption, oxidative stress, psychological function, energy metabolism
- Padayatty et al., Ann Intern Med 2004, vitamin C pharmacokinetics: implications for oral and intravenous use
Where to get it
Shop Vitamin C (ascorbic acid) on AmazonSponsored · As an Amazon Associate, Healicus earns from qualifying purchases.