Vitamin C as an Antiviral ~ It’s All About Dose

One of the most frequent questions from Orthomolecular Medicine News Service readers is: Just how much vitamin C should I take? Our bodies cannot make vitamin C (ascorbate), although most animals can. We must get it from our food and from supplements. But how much do we really need?

Persistent arguments on this question may be settled by looking at how much vitamin C animals manufacture in their bodies. The answer is: quite a lot. Most animals make the human body-weight equivalent of 5,000 to 10,000 milligrams a day. It is unlikely that animals would have evolved to make this much vitamin C if they did not need it and use it. Indeed, cells in many human body tissues concentrate vitamin C by 25-fold or more over bloodconcentration.

Each person’s need for vitamin C differs because of differences in genetics and individual biochemistry [1,2,3]. Further, our bodies undergo different stresses, and we certainly eat different foods. Therefore, the daily need for ascorbate to maintain health for an adult varies between 2,000 – 20,000 mg/day. Linus Pauling personally took 18,000 mg of vitamin C daily. Although he was often ridiculed for this, it is interesting to note that Dr. Pauling had two more Nobel prizes than any of his critics. He died at age 93. Abram Hoffer, MD, a colleague of Pauling’s, took megadoses of vitamin C and successfully gave it to thousands of patients over 55 years of medical practice. Dr. Hoffer died at age 91.

Antiviral Function

When we are challenged with a viral infection, our need for vitamin C can rise dramatically, depending on the body’s immune function, level of injury, infection, or environmental toxicity such as cigarette smoke [4,5]. Ascorbate at sufficiently high doses can prevent viral disease and greatly speed recovery from an acute viral infection. Surprising to some, this was originally observed by physicians in the 1940s and has been verified and re-verified over the last 60 years by doctors who achieved quick and complete recovery in their patients with ascorbate mega-doses [5].

The effective therapeutic dose is based on clinical observation and bowel tolerance. Clinical observation is essentially “taking enough C to be symptom-free, whatever that amount may be.” Bowel tolerance means exactly what you think it means: the amount that can be absorbed from the gut without causing loose stools. [5,6]

Very high doses, 30,000 – 200,000 mg, divided up throughout the day, are remarkably non-toxic and have been documented by physicians as curing viral diseases as various as the common cold, influenza, hepatitis, viral pneumonia, and even polio. [4,5,7] On first reading this may sound incredible. We invite interested persons to read further, starting with the references listed below, and especially Dr. Frederick R. Klenner’s Clinical Guide to the Use of Vitamin C. This short book is posted in its entirety at

Mechanism For Ascorbate Antiviral Effect

Several mechanisms for vitamin C’s antiviral effect are known or suggested from studies. [4,8] The antioxidant property of ascorbate promotes a reducing environment in the bloodstream and tissues, enhancing the body’s response to oxidative stress from inflammation [9], thereby helping to fight microbes and viruses that propagate in stressful conditions. [10] Ascorbate has been shown to have specific antiviral effects in which it inactivates the RNA or DNA of viruses [11,12,13], or in the assembly of the virus [14]. Vitamin C is also involved in enhancing several functions of the immune system. Ascorbate can enhance the production of interferon, which helps prevent cells from being infected by a virus [15,16].

Ascorbate stimulates the activity of antibodies [17], and in megadoses seems to have a role in mitochondrial energy production [18]. It can enhance phagocyte function, which is the body’s mechanism for removing viral particles and other unwanted debris [4]. White blood cells, involved in the body’s defense against infections of all types, concentrate ascorbate up to 80 times plasma levels, which, if you take enough vitamin C, allows them to bring huge amounts of ascorbate to the site of the infection [4]. Many different components of the immune response, B-cells, T-cells, NK cells, and also cytokine production, all with important roles in the immune response, are enhanced by ascorbate [19-23]. Additionally, ascorbate improves the immune response from vaccination [24,25].


Vitamin C at high doses is effective in preventing viral infection and enhancing recovery. Several mechanisms are known, including specific viral anti-replication processes and enhancement of many components of the body’s cellular immune system. When taken at an appropriate dose in a timely manner, ascorbate is our best tool for curing acute viral illness.


[1] Williams RJ, Deason G (1967) Proc Natl Acad Sci USA. 57:1638-1641. Individuality in vitamin C needs.
[2] Pauling L (1986) How to Live Longer And Feel Better, by Linus Pauling (Paperback – May 2006) ISBN-13: 9780870710964
[3] Hoffer A, Saul AW (2009) Orthomolecular Medicine for Everyone: Megavitamin Therapeutics for Families and Physicians. ISBN-13: 9781591202264
[4] Levy TE (2002) Curing the Incurable: Vitamin C, Infectious Diseases, and Toxins. ISBN-13: 9781401069636
[5] Hickey S, Saul AW (2008) Vitamin C: The Real Story, the Remarkable and Controversial Healing Factor. ISBN-13: 9781591202233
[6] Cathcart RF (1981) Vitamin C, titrating to bowel tolerance, anascorbemia, and acute induced scurvy. Med Hypotheses. 7:1359-1376.
[7] Klenner FR (1979) The significance of high daily intake of ascorbic acid in preventive medicine, in: Physician’s Handbook on Orthomolecular Medicine, Third Edition, 1979, Roger Williams, PhD, ed., p 51-59.
[8] Webb AL, Villamor E (2007) Update: Effects of antioxidant and non-antioxidant vitamin supplementation on immune function. Nutrition Reviews 65:181-217
[9] Wintergerst ES, Maggini S, Hornig DH (2006) Immune-enhancing role of vitamin C and zinc and effect on clinical conditions. Ann Nutr Metab. 50:85-94.
[10] Kastenbauer S, Koedel U, Becker BF, Pfister HW (2002) Oxidative stress in bacterial meningitis in humans. Neurology. 58:186-191.
[11] Murata A, Oyadomari R, Ohashi T, Kitagawa K. (1975) Mechanism of inactivation of bacteriophage deltaA containing single-stranded DNA by ascorbic acid. J Nutr Sci Vitaminol (Tokyo). 21:261-269.
[12] Harakeh S, Jariwalla RJ, Pauling L (1990) Suppression of human immunodeficiency virus replication by ascorbate in chronically and acutely infected cells. Proc Natl Acad Sci USA. 87:7245-7249.
[13] White LA, Freeman CY, Forrester BD, Chappell WA (1986) In vitro effect of ascorbic acid on infectivity of herpesviruses and paramyxoviruses. J Clin Microbiol. 24:527-531.
[14] Furuya A, Uozaki M, Yamasaki H, Arakawa T, Arita M, Koyama AH (2008) Antiviral effects of ascorbic and dehydroascorbic acids in vitro. Int J Mol Med. 22:541-545.
[15] Gerber, WF (1975) Effect of ascorbic acid, sodium salicylate and caffeine on the serum interferon level in response to viral infection. Pharmacology, 13: 228.
[16] Karpinska T, Kawecki Z, Kandefer-Szerszen M (1982) The influence of ultraviolet irradiation, L-ascorbic acid and calcium chloride on the induction of interferon in human embryo fibroblasts. Arch Immunol Ther Exp (Warsz). 30:33-37.
[17] Anderson R, Dittrich OC (1979) Effects of ascorbate on leucocytes: Part IV. Increased neutrophil function and clinical improvement after oral ascorbate in 2 patients with chronic granulomatous disease. S Afr Med J. 1;56476-80.
[18] Gonz lez MJ, Miranda JR, Riordan HD (2005) Vitamin C as an Ergogenic Aid. J Orthomolecular Med 20:100-102.
[19] Kennes B, Dumont I, Brohee D, Hubert C, Neve P (1983) Effect of vitamin C supplements on cell-mediated immunity in old people. Gerontology. 29:305-310.
[20] Siegel BV, Morton JI (1984) Vitamin C and immunity: influence of ascorbate on prostaglandin E2 synthesis and implications for natural killer cell activity. Int J Vitam Nutr Res. 54:339-342.
[21] Jeng KC, Yang CS, Siu WY, Tsai YS, Liao WJ, Kuo JS (1996) Supplementation with vitamins C and E enhances cytokine production by peripheral blood mononuclear cells in healthy adults. Am J Clin Nutr. 64:960-965.
[22] Campbell JD, Cole M, Bunditrutavorn B, Vella AT (1999) Ascorbic acid is a potent inhibitor of various forms of T cell apoptosis. Cell Immunol. 194:1-5.
[23] Schwager J, Schulze J (1997) Influence of ascorbic acid on the response to mitogens and interleukin production of porcine lymphocytes. Int J Vitam Nutr Res. 67:10-16.
[24] Banic S (1982) Immunostimulation by vitamin C. Int J Vitam Nutr Res Suppl. 23:49-52. [25] Wu CC, Dorairajan T, Lin TL (2000) Effect of ascorbic acid supplementation on the immune response of chickens vaccinated and challenged with infectious bursal disease virus. Vet Immunol Immunopathol. 74:145-152.
For more information: The peer-reviewed Orthomolecu-lar Medicine News Service is a non-profit and non-commercial informational resource.
Editorial Review Board:
Carolyn Dean, MD, ND.
Damien Downing, MD.
Michael Gonzalez, D.Sc., PhD.
Steve Hickey, PhD.
James A. Jackson, PhD
Bo H. Jonsson, MD, PhD
Thomas Levy, MD., J.D.
Jorge R. Miranda-Massari, Pharm.D.
Erik Paterson, MD.
Gert E. Shuitemaker, PhD. Andrew W. Saul, PhD., Editor and contact person. Email:

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