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ingestible · for immune support

Vitamin C (100-200 mg/day)

Reviewed by the Nimbera editorial team · Last updated May 2026

Carr & Maggini (2017, Nutrients, PMID 29099763) reviewed evidence that vitamin C supports neutrophil chemotaxis, phagocytosis, and microbial killing. A meta-analysis of 53 trials cited in the same review found prophylactic doses reduced cold duration by 8% in adults and 14% in children, and halved cold incidence in people under extreme physical stress.$5-$15 for a 3-month supply at 200 mg/day.

How to use

Take 100-200 mg daily with food. This range saturates plasma levels without excess. Higher therapeutic doses may be used during acute illness - consult a provider.

How it works

Vitamin C accumulates in neutrophils and lymphocytes at concentrations far above plasma levels, protecting these immune cells from oxidative damage during pathogen killing. It also supports collagen synthesis in mucosal barriers - the body's first line of defence.

Where to buy

Pharmacies, supermarkets, and health food stores. Look for ascorbic acid or calcium ascorbate forms.

Typical cost: $5-$15 for a 3-month supply at 200 mg/day.

Safety notes

Doses above 2,000 mg/day may cause diarrhoea and gastrointestinal discomfort. Those with kidney disease or a history of kidney stones should consult a doctor before supplementing.

Drug & supplement interactions

  • Always tell your doctor or pharmacist about any supplements you take.
  • Interactions can occur with prescription medications, blood thinners, and immunosuppressants.
  • Herbal remedies can affect how the body absorbs or metabolises drugs.
  • Check drugs.com interactions checker before starting.

Clinical source

Carr AC & Maggini S, Vitamin C and Immune Function, Nutrients, 2017

This information is compiled from primary clinical literature and is for informational purposes only. It is not a substitute for professional medical advice. Read our full disclaimer.