Vitamin C for coronavirus prevention with daily vitamin C supplementation
In a 2013 meta-analysis of 29 controlled trials with 11,306 participants, H.Hemilä showed that regular vitamin C intake of around 1 g/day did not prevent upper respiratory tract infections (URTIs). However, the same trials found that vitamin C did shorten and alleviate URTIs that occurred during the period of vitamin C administration. In adults the duration of infections was reduced by 8% (approx half a day) and in children by 14% (approx 1 day).
The last UK placebo controlled trial (2002) best illustrates the meaningful clinical difference between number of colds, cold duration and severity. One hundred sixty-eight volunteers were randomized to receive a placebo or a vitamin C supplement, two 500mg tablets daily, over a 60-day period between November and February. The researchers used a five-point scale to assess their health and recorded any common cold infections and symptoms in a daily diary. Compared with the placebo group, the vitamin C treatment group had fewer colds (37 vs 50, P<.05), but even fewer virally challenged ‘cold’ days (85 vs 178) and a shorter duration of severe symptom days (1.8 vs 3.1 days, P<.03). The number of participants who had 2 colds during their trial (2/84 on vitamin C vs 16/84 in the placebo group; P = .0004).
The evidence for a significant reduction in duration and severity of colds is greater and more consistent with a intake of 2 or more g/day. Given that COVID-19 is often much more severe than ordinary URTIs, the above estimates might justify a regular increased daily intake of vitamin C of at least 2 g/day while the prevalence of COVID-19 is high, and even more during an infection.
Vitamin C for coronavirus treatment - taking vitamin C during infection
While a relatively small amount of vitamin C is sufficient for healthy people the effective use of vitamin C depends of how much is required to support the immune system. When a person is infected the amount required increases dramatically. This is illustrated by the depletion of vitamin C levels in leucocytes, critical for immune response, during colds and flu. These critical immune cells normally have more than 10-fold higher vitamin C levels than other cells. An intake of 6 g/day has been shown to restore normal vitamin C levels in leucocytes during colds. This suggests that similar daily doses may be required to have a symptom reducing effect. Studies giving 3 vs 6 or 4 vs 8 g/day have shown the higher the dose the greater the effect with a 20% decrease in cold duration with 6 to 8 g/day. This equates to 1.5 to 2 days shorter colds. However, 46% of those taking 8 g/day in the first day of a cold report being symptom free after 24 hours. Case reports indicate greater effect with doses of 15+ g/day, titrating the dose to ‘bowel tolerance’ levels. During infection most people can tolerate 1 g/hr without diarrhoea. This was Dr Linus Pauling’s recommendation – to start with a loading dose of 2 or 3 g, then take 1g/hr until symptoms disappear.
Vitamin C for hospitalised & ICU patients with pneumonia, sepsis or COVID-19
Vitamin C supplementation has been shown effective, even at low doses between 0.2g and 1.6 g/day, in reducing incidence, speeding up recovery and reducing mortality in those with pneumonia. A recent study by A.Carr has reported depleted plasma vitamin C status (23µmol/l) in 44 hospitalised patients with pneumonia, compared to healthy controls (56µmol/l). The most severe patients in ICU had levels averaging 11µmol/l, which is the level that defines scurvy.
P.Marik has reported similar findings in 22 ICU patients with sepsis with levels of 14.1nmol/l  and recommends giving 1.5 g of vitamin C every 6 hours intravenously. Marik has also reported that all COVID-19 patients in ICUs so far tested by his group (Frontline Covid-19 Critical Care - FLCCC) have deficient or undetectable levels of vitamin C sufficient to diagnose scurvy.
M.Vizcachipi, at the Chelsea and Westminster NHS Hospital, using 1g vitamin C every 12 hours, has reported a mortality rate (25.1% in females and 38.2% in males) 21% lower than the UK national average (ICNARC data) of 49%, thus saving one in five lives.
Vitamin C to prevent or shorten ICU hospitalisation, mechanical ventilation and mortality
One of the major causes for concern with COVID-19 is the relatively high proportion of cases requiring intensive care unit (ICU) treatment. H.Hemila’s meta-analysis of 12 trials with 1,766 non-COVID patients in ICU found that vitamin C shortened ICU stay by 8%. Another meta-analysis of eight trials found that vitamin C shortened the duration of mechanical ventilation in patients who required the longest ventilation.
There is evidence that vitamin C levels decline precipitously in critically ill patients and that administration of an appropriate dose can dramatically reduce complications and mortality. Although 0.1 g/day of vitamin C can maintain a normal plasma level in a healthy person, much higher doses (1 – 4 g/day) are needed to increase plasma vitamin C levels of critically ill patients to within the normal range. The FLCCC give 3 g of intravenous vitamin C every six hours, together with steroids and anti-coagulants. FLCCC are reporting zero COVID-19 deaths in their ICUs in those without end-stage comorbidities.
Preliminary, unpublished results of a randomised, placebo controlled trial in Wuhan of mechanically ventilated ICU patients given either 12 g of intravenous vitamin C twice daily or sterile water placebo in a saline drip show 24% mortality on the vitamin C group vs 35% in the placebo group, with significant results in the reduction of the inflammatory marker IL-6 and of mortality in those with the worst pulmonary function index (PF<150).
Overall, a variety of studies have shown that high-dose oral supplements of vitamin C can reduce the risk of infection and effectively reduce the intensity of viral infections, and in a hospital ICU setting high-dose oral and IV vitamin C in combination with a well-established critical care protocol can treat COVID-19 to prevent serious pneumonia, need for mechanical ventilation, organ failure, septic shock, and death.
 Hemilä H, Chalker E. (2013) Vitamin C for preventing and treating the common cold.
Cochrane Database Syst Rev. 2013 Jan 31;(1):CD000980. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD000980.pub4/full
 See Hemilä above
 Van Straten, M., Josling, P. Preventing the common cold with
a vitamin C supplement: A double-blind, placebo-controlled survey. Adv
Therapy 19, 151 (2002).
 Hume, R.;Weyers, E. Changes in
leucocyte ascorbic acid during the common cold. Scott. Med. J. 1973, 18,
 Karlowski, T.R.; Chalmers, T.C.; Frenkel, L.D.; Kapikian, A.Z.; Lewis, T.L.; Lynch, J.M. Ascorbic acid for the common cold: A prophylactic and therapeutic trial. JAMA 1975, 231, 1038–1042. https://pubmed.ncbi.nlm.nih.gov/163386/
 Anderson, T.W.; Suranyi, G.; Beaton, G.H. The effect on winter illness of large doses of vitamin C. Can.
Med. Assoc. J. 1974, 111, 31–36. https://pubmed.ncbi.nlm.nih.gov/4601508/
 Hemilä H Vitamin C and Infections Nutrients. 2017 Apr; 9(4): 339. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5409678/
 Carr AC et al., ‘Patients with community acquired pneumonia exhibit depleted vitamin C status and elevated oxidative stress’ Nutrients 2020, 12, 1318; doi:10.3390/nu12051318
 Marik’s source of vit C levels in sepsis data
 Marik and Hooper Critical Care (2018) 22:23 DOI 10.1186/s13054-018-1950-z
 Awaiting publication. See https://covid19criticalcare.com/Unpublished data, reported by Dr Paul Marik in podcast: https://patrickholford.podbean.com/e/flu-fighters-series-1-ep-4-use-of-intravenous-vitamin-c-for-front-line-staff/
 Vizcachipi M, Preprint at https://www.medrxiv.org/content/10.1101/2020.05.08.20088393v1
 Hemilä H, Chalker E. Vitamin C can shorten the length of stay in the ICU: a meta-analysis. Nutrients 2019;11:E708 https://www.mdpi.com/2072-6643/11/4/708
 Hemilä H, Chalker E. Vitamin C may reduce the duration of mechanical ventilation in critically ill patients: a meta-regression analysis. J Intensive Care 2020;8:15. https://jintensivecare.biomedcentral.com/articles/10.1186/s40560-020-0432-y
 Carr AC, Rosengrave PC, Bayer S, Chambers S, Mehrtens J, Shaw GM. Hypovitaminosis C and vitamin C deficiency in critically ill patients despite recommended enteral and parenteral intakes. Crit Care 2017;21:300; see also ref 12 above.
 de Grooth HJ, Manubulu-Choo WP, Zandvliet AS, Spoelstra-de Man AM, Girbes AR, Swart EL, Oudemans-van Straaten HM. Vitamin C pharmacokinetics in critically ill patients: a randomized trial of four IV regimens. Chest 2018;153:1368–1377. https://journal.chestnet.org/article/S0012-3692(18)30393-3/fulltext; see also ref 12 above.
 See https://covid19criticalcare.com/
 Personal communication from Dr Z. Peng, 10th April 2020. Publication pending.