Vitamin C (ascorbic acid) is a water-soluble antioxidant essential for collagen synthesis, immune function (particularly neutrophil function), iron absorption (enhances non-haem iron absorption), wound healing, and protection against oxidative damage. It is the primary water-soluble antioxidant in plasma and supports regeneration of vitamin E.
Severe deficiency causes scurvy — characterised by perifollicular haemorrhages, joint and muscle pain, impaired wound healing, swollen bleeding gums, and fatigue — now uncommon in Australia but still seen in people with very restricted diets, alcohol dependence, and older people living alone. Vitamin C is found almost exclusively in fresh fruits and vegetables.
FAQs
What are the first signs of scurvy?
Fatigue and irritability appear first, followed by joint and muscle pain, perifollicular haemorrhages (bleeding around hair follicles), and swollen bleeding gums. In children, bone pain and impaired growth occur. Scurvy responds rapidly to vitamin C replacement.
Can vitamin C cure the common cold?
Vitamin C does not prevent colds in most people, but regular supplementation (200-500 mg/day) modestly reduces cold duration. It may have more significant benefit in people with physical stress (military personnel, athletes in extreme conditions).
Is high-dose vitamin C safe?
Oral vitamin C above 1000 mg/day causes diarrhoea in many people (GI tolerance limit). Very high doses can increase kidney stone risk in people prone to oxalate stones. At physiological doses (200-500 mg/day), vitamin C is safe.
How does vitamin C help with iron absorption?
Vitamin C reduces ferric iron (Fe3+) to ferrous iron (Fe2+), which is better absorbed in the small intestine. Taking a vitamin C-rich food or supplement with plant-based iron sources can increase absorption by up to 3-fold.
