Nutritional Influences on Illness: Do Vitamin C Supplements Really Help the Common Cold?

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Nutritional Influences on Illness: Do Vitamin C Supplements Really Help the Common Cold?

While the first reports suggesting that vitamin C. may reduce cold symptoms were published in the 1930's and 1940's, serious interest in the subject developed following the publication of Vitamin C and the Common Cold by Linus Pauling in 1970.( 1) Based on his review of published studies, Pauling stated that supplemental ascorbic acid, in doses of 1 g daily or greater, significantly decreases both the incidence and severity of the common cold. The following year. Pauling published one of the very first meta-analyses in the field of medicine, in which he demonstrated a significant decrease in total morbidity in subjects ingesting vitamin C supplements.( 2)

Since then almost two dozen placebo-controlled studies have sought to determine whether vitamin C supplementation can benefit the common cold. Essentially all of theft, have found a therapeutic effect! Why, then, is the subject still considered by many in the mainstream to be controversial? Wa may finally have the explanation. In 1975, Thomas Chalmers published his own recta-analysis oft, he studies completed up to then. He concluded that, "since there are no data on the long-term toxicity of ascorbic acid...in doses of I g or more per day,...the minor benefits of questionable validity are not worth the potential risk...."( 3)

His paper has been quoted ever since as evidence of the folly of vitamin C supplementation. Recently, however, Hemilä and Herman have published a retrospective analysis of Chalmers' review and -- guess what? His review was full of errors! For example, he included in his meta-analysis a study in which subjects only received 25 to 50 mg of vitamin C daily. Even worse, he used values for his analysis that were inconsistent with those published by the researchers!( 4) Hemilä and Herman believe that, if these errors were corrected, the data available to Chalmers would have forced him to c, include that vitamin C supplementation does, in fact, reduce the duration of the common cold.( 4)

What does current evidence suggest regarding ascorbate supplementation for colds? Assuming that the dosage is in the range of one to eight grams daily, vitamin C given at the start of a cold reduces the severity of cold symptoms by an average of 23%,( 5) and reduces the duration of the cold by as much as 48%,( 6) effects that may be dose-dependent.( 6) However, the studies have failed to find satisfactory evidence that prophylactic vitamin C reduces susceptibility to colds.

We know that, during a cold, the concentration of vitamin C falls in both the plasma and leukocytes.( 7) Neutrophils become activated as pact of the cellular immune defenses, and activated neutrophils greatly enhance ascorbate oxidation.( 8) Supplementing with vitamin C elevates plasma ascorbic acid which then passes into ascorbate-depleted tissues( 9) where it may enhance the neutrophil's ability to dispose of the infectious agents.( 10, 11) Moreover, the vitamin has been shown to enhance interferon production( 12) and may actually disrupt the nucleic-acid strands of viruses.( 13)

What we still have to learn is the ideal dosage for maximal benefits. Pauling suggested at least 6 grams a day in order to keep leukocytes adequately supplied.( 14) The latest research suggests that, in healthy people, leukocytes become saturated at 100 mg of ascorbate daily and the plasma is completely saturated at 1000 mg daily;( 15) perhaps someone will now decide to do a similar study on people with colds so we can finally get a more definitive answer.

Doctor Werbach cautions that the nutritional treatment of illness should be supervised by physicians or practitioners whose training prepares them to recognize serious illness and to integrate nutritional interventions safely into the treatment plan.

Next Month:

When is Depression Due to a Nutrient Deficiency?

References
(1.) Pauling L. Vitamin C and the Common Cold. San Francisco, Freeman, 1970.

(2.) Pauling L. The significance of the evidence about ascorbic acid and the common cold. Proc Natl Acad Sci USA 68:2678-81, 1971.

(3.) Chalmers TC. Effects of ascorbic acid on the common cold. An evaluation of the evidence. Am J Med 58:532-6, 1975.

(4.) Hemilä H, Herman ZS. Vitamin C and the common cold: a retrospective analysis of Chalmers' review. J Am Coll Nutr 14(2):116-23, 1995.

(5.) Hemilä H. Does vitamin C alleviate symptoms of the common cold? - a review of current evidence. Scand J Infect Dis 26:1-6, 1994.

(6.) Hemilä H. Vitamin C and the common cold. Br J Nutr 67:3-16, 1992.

(7.) Hume R, Weyers E. Changes in leucocyte ascorbic acid during the common cold. Scot Med J 18:3-7, 1973.

(8.) Roberts P et al. Vitamin C and inflammation. Med Biol 62:88, 1984.

(9.) Wilson CW, Greene M, Loh HS. The metabolism of supplemental vitamin C during the common cold. J Clin Pharmacol 16(1):19-29, 1976.

(10.) Anderson R, Oosthuizen R, Maritz R, et al. The effects of increasing weekly doses of ascorbate on certain cellular and humoral immune functions in normal volunteers. Am J Clin Nutr 33(1):71-6, 1980.

(11.) Patrone F, Dallegri F. Vitamin C and the phagocytic system. Acta Vitaminol Enzymol 1:5-10, 1979.

(12.) Geber WF et al. Effect of ascorbic acid, sodium salicylate, and caffeine on the serum interferon level in response to viral infection. Pharmacology 13(3):228-33, 1975.

(13.) Murata A. Virucidal activity of vitamin C for prevention and treatment of viral diseases, in Takezi Hasegawa, Ed. Proc First Int Congr IAMS. Science Council of Japan, 1975.

(14.) Pauling L. Why you need vitamin C to fight your cold, in The Good Drugs Do to Better your Health. Medical Tribune (suppl), 1976.

(15.) Levine M. Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance. Proc Natl Acad Sci USA 93:3704-9, 1996

Reprinted with permission from the Internationational Journal of Alternative and Complementary Medicine, Green Library, 9 Rickett St., Fulham, London SW6 1RU, United Kingdom.

Townsend Letter for Doctors & Patients.

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By Melvyn R. Werbach

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