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Vitamin C in Treatment of the Common Cold


By: Dawn Myers




Is Vitamin C the cure for the common cold? Will it reduce the severity and duration of a cold? Will it prevent you from ever having another cold? Of course, we would all like to think that would be true, but whatís the real effect of Vitamin C supplements?


What is Vitamin C and Where Can I Find It?


Vitamin C is water soluble and functions as an antioxidant and as a coenzyme. Furthermore, it can perform different functions in various situations, such as aiding in collagen formation for teeth, cartilage, and connective tissue and aiding in the formation of new tissue in wound healing. Vitamin C can be found in foods such as broccoli, brussel sprouts, cantaloupe, grapefruit, kiwi, oranges, peppers, and strawberries. Presently the RDA is 60 mg.


What are the Dangers?


Vitamin C Deficiency


Vitamin C deficiency is rather rare in Western countries, however, it still occurs in alcoholics, drug addicts, and the elderly--groups whose dietary intakes are often very poor. Marginal deficiency symptoms are gingivitis, loose teeth, aching limbs and joints, poor wound healing, and weakening of tissues which increases the risk of infection. (Grodner, Anderson, & DeYoung; 1996)


Vitamin C Toxicity


Despite the fact that Vitamin C is essential to good health, you can have too much of a good thing. Although toxicity from foods high in Vitamin C does not occur, taking supplements in large doses (1 gm to 15 gm) may result in symptoms such as cramps, nausea, diarrhea, kidney stones, and gout. After receiving excessive amounts of Vitamin C, the body begins to destroy much of the excess Vitamin C that is in circulation. Furthermore, there is a potential rebound effect upon abruptly stopping supplementation for the body is still in the process of destroying the vitamin. (Grodner, Anderson, & DeYoung; 1996) Brown (1973) also warned that chronic massive doses of Vitamin C resulted in increased mobilization of calcium and phosphate from the skeletons of chicks, weakening the bone structure. Although unsure if massive doses would produce the same effect in humans, the author warned against chronic massive supplementation.


Vitamin C and Colds: How Does it Work?

Vitamin C is often used for both prophylactic and therapeutic purposes. Wilson, Loh, and Foster (1972) state that the prophylactic effect refers to the ability of vitamin C to prevent a cold Furthermore, commencement of administration of vitamin C when cold symptoms first appear constitutes the therapeutic use. Rhinoviruses, which cause common colds, appear to cause damage by attracting the bodyís defense cells to the site of injury. Vitamin C may be able to reduce the severity of symptoms during a common cold by reducing the number of oxidizing agents produced by the bodyís defense cells.



Vitamin C and Colds: What Do the Supplements Claim?


"Useful in the prevention and cure of cold. . .a natural and invaluable aid to health and

well-being. "


"The great this about Vitamin C is that you canít get too much of it..."


"Daily Amount/Application: 2,000 milligrams, taken as 4 divided doses"


"Clinical studies discovered its efficacy in treating the common cold years ago and we

have all been enjoying the benefits ever since: one or more grams of vitamin C a

day can reduce the intensity, the duration of a cold"


††††††††††††††††††††††††††††††††††† (


Procedure for seeing if vitamin C will help you prevent or minimize colds:

††††††††††† "Take vitamin C to bowel tolerance limit twice a day."

††††††††††† "If you start to feel a cold coming on, increase this level to at least 1000mg per

††††††††††††††††††††††† hour or as much as you tolerate. This must start IMMEDIATELY."

††††††††††† "Continue this for as long as your bowel tolerance level stays high."

If this is unsuccessful, you must not have taken as much as advised.


". . .vitamin C is safe, there are no contraindications. . .of side effects"




"Besides buying Daily-C for its preventive and healing benefits, many consumer find it is a

††††††††††† healthier, fat-free alternative to candy."


††††††††††††††††††††††††††††††††††† (


What Does the Research Show?


For many years, large doses of ascorbic acid (commonly known as vitamin C) have been used for both the prevention and the treatment of the common cold; however, research has yet to prove that vitamin C has a marked effect.


Wilson, Loh, and Foster (1973)


Wilson, Loh, and Foster sought to compare the incidence, duration, severity, and total intensity of cold characteristics, and of cold frequencies between different treatment groups. Subjects were students in four boarding schools located in Dublin, Ireland. All children in one male and one female school received tablets containing 200 mg vitamin C, or placebo tablets, daily on a double blind basis over a period of nine months. Children in the other two schools received 200 or 500 mg tablets of vitamin C.


The authors divided colds into four cold categories: 1) Toxic colds, consisting of symptoms such as sore throat, headache, fever, and feeling "out of sorts"; 2) Catarrhal colds, consisting of symptoms such as cold in the head, cough, nasal obstruction, and nasal discharge; and 3) Whole colds which consisted of toxic and catarrhal cold symptoms in combination.


Results: In females, 200 mg of vitamin c did not have significant effects on characteristics of toxic colds in comparison with placebo therapy. However it was associated with a significant reduction in severity and intensity of catarrhal colds--it reduced the severity of catarrhal colds by 27% and their intensity by 43%.


In males, 200 mg had no significant effect on overall incidence, duration, severity, or total intensity of sxs in either toxic or catarrhal colds.


Increasing the dose to 500 mg did not have any significant effect on either catarrhal colds or toxic colds among girls in comparison to the effects of the 200 mg dosage. 500 mg also had no significant effect on catarrhal colds in boys. However, 500 mg did cause a slight reduction in duration and severity of toxic colds in boys.


200 mg reduced the severity and total intensity of whole colds in girls, but had no beneficial effect in boys. 500 mg was associated with increased incidence and duration of whole colds in both girls and boys in comparison with the 200 mg doses.


Although the authors suggest that boys may need a higher does of vitamin C to see the same effects as those produced in girls, this study seems to imply that not only is vitamin C in large doses not beneficial for the most part, but it could be potentially dangerous. Furthermore, the slight increase in incidence of colds suggests that there may not be statistically significant prophylactic connection between vitamin C and colds.


Coulehan, Reisinger, Rogers, and Bradley (1974)


Coulehan, Reisinger, Rogers, and Bradley (1974) designed a study to test the hypothesis that daily vitamin C supplements and placebo supplements have identical effects as prophylactic agents in respiratory disease. The authors conducted a double-blind study in a Navajo boarding school (n = 641 children) in which 1 and 2 g vitamin C supplements versus placebo were used.


The authors found that children taking 1 or 2 g of vitamin C supplements were ill fewer days than those taking the placebo. However, the prophylactic benefits were modest and not entirely consistent throughout the sample. Furthermore, the authors reported that no significant differences were found in days of morbidity from respiratory illnesses among children receiving the vitamin C supplement and those receiving the placebo except for older girls in the sample. As for symptoms, the authors reported fewer days with cough and nasal discharge in those taking vitamin C supplements as compared to those taking the placebo; however, other symptoms were unaffected by vitamin C.


Anderson, Reid, and Beaton (1972)


Anderson, Reid, and Beaton (1972) designed a study to determine whether there was any effect (prophylactic or therapeutic) from large doses of vitamin C. Using 818 volunteers in an attempt to get a sample generally representative of the general population (with the exception of their cold susceptibility), subjects were instructed to take four tablets (250 mg vitamin C/tablet or placebo) a day each day for four months, increasing to sixteen tablets each day for the first three days of any illness.


Results: The authors failed to find a significant reduction if episodes of illness; however, they did report a significant reduction in symptoms and duration in those subjects taking vitamin C as compared to those taking the placebo. Although this study did have a rather large sample and a seemingly well-controlled double-blind format, there is the potential problem of defining "cold." Every subjectís definition and understanding of what is meant by a cold was likely slightly different from person to person; thus, there is the potential for variability in when the subjects began increasing their doses due to different perspectives of what defines the beginning symptoms of a cold.


Karlowski, Chalmers, Frenkel, Kapikian, Lewis, and Lynch (1975)


Karlowski, Chalmers, Frenkel, Kapikian, Lewis, and Lynch (1975) sought to perform a long-term prospective double-blind trial with high doses of ascorbic acid. The trial was designed to measure as well as distinguish between the prophylactic and therapeutic effects of vitamin C.


Employees who volunteered from the National Institutes of Health constituted the sample (n = 313). Exclusion criteria were: 1) history of diabetes, gout, renal stones, or respiratory symptoms of probable allergic origin; 2) women who were pregnant or anticipated pregnancy in the following year; 3) taking anticoagulants or medications producing side effects involving the respiratory system; 4) being unwilling/unable to take vitamins containing ascorbic acid; and 5) elevated blood uric acid level.


The prophylactic dose of the study drug was two capsules taken three times a day. When a subject had a cold, the therapeutic dose was double the prophylactic dose. Each test capsule contained 500 mg ascorbic acid, 180 mg lactose, and 5 mg magnesium stearate. Each placebo capsule contained 645 mg of lactose and 5 mg magnesium stearate. Subjects were given the study drug (or the placebo) in their prophylactic or therapeutic dose, in both doses, or in neither dose.


Results: The authors found that the therapeutic dose has less of an effect than the prophylactic dose on the severity of cold symptoms. Furthermore, the data reveal the discrepancy between the effects of vitamin C on the incidence and the severity of colds.

Those receiving vitamin C at any time had slightly fewer colds, with milder symptoms, and of shorter duration than those receiving only the placebo; however the difference was minute. Unfortunately, at the end of the study, it was revealed that a significant number of the volunteers had accurately guessed the condition to which they had been assigned. Factoring this into the analysis, the results found were lessened for those who had known which condition they were in. By knowing if they were taking vitamin C or a placebo could have induced effects simply by the power of suggestion.


Tyrell, Craig, Meade, and White (1977)


Tyrell, Craig, Meade, and White (1977) conducted a randomized controlled trial to study the effect of 10 g or ascorbic acid during the first two and one-half days on the symptoms of the common cold. 753 male and 771 female volunteers from Salisbury, London, and Merseyside, England constituted the sample. Volunteers were randomly placed in either the active treatment condition or the placebo condition and were given a tube of 10 tablets. Four tablets were taken daily for the first two and one-half days of a cold. The volunteers were also instructed to mark what cold symptoms were present.


Results: The authors found no evidence that vitamin C was useful in ameliorating the upper respiratory or the general symptoms of the common cold. Unlike other studies which have shown greater benefits in women than in men, the authors found that men taking vitamin C had fewer colds than those taking the placebo; however, this effect was not found in the women.


Elwood, Lee, St. Leger, Baird, and Howard (1976)


Elwood, Lee, St. Leger, Baird, and Howard (1976) performed a randomized controlled trial of the effect of a daily dose of 1g ascorbic acid in the prevention of respiratory infections which was conducted among young women in South Wales in the winter of 1973-74. Colds were divided into two categories: 1) Simple colds, consisting of a running nose, and/or sneezing, and/or sore throat, with or without other symptoms such as fever, headache, or malaise; and 2) Chest colds, consisting of a cough, or any other chest symptom either on its own or with any other symptom.


The women were given sufficient tablets to last 100 days. These contained either

1g ascorbic acid or a matching placebo, and one was to be taken each day. A record

card was given, on which was to be recorded any respiratory symptom which was sufficiently severe to "bother her". These cards were given and recorded at monthly intervals.


Results: The authors found that small doses of ascorbic acid have little or no effect on the common cold. The collected data are consistent with a small preventive effect of vitamin C on colds.


Charleston, and Clegg (1972)


Charleston and Clegg (1972) conducted a study to assess the effect of 500 mg of vitamin C on cold frequency and duration. 47 subjects took 500 mg of vitamin C daily for fifteen weeks while 43 subjects took a placebo of lactose and 5% citric acid. Total number of colds and the average number of colds per person were calculated for both the experimental and control groups.


Results: The authors found that the incidence of colds was reduced by 49% in the experimental group as compared to the control group. These findings should be analyzed with caution as the study would have been more effective if it had been double-blind, with larger groups, longer running time, and perhaps even larger levels of vitamin C. Furthermore, the authors fail to consider the possibility that simply knowing whether one was receiving vitamin c or not had an effect on the results.


Summary: Is Vitamin C Beneficial or Not?


Clearly, the evidence for vitamin Cís ability to prevent incidence of and/or reduce the severity and duration of colds is mixed and quite controversial. While some studies suggest that vitamin C is beneficial to cold duration and severity as well as cold prevention, others find no evidence to support these claims. Unfortunately, because of the great variability in the subjects used, symptoms measured, and dosage of vitamin C used within the studies conducted it is difficult to combine the results and come to a definite conclusion. However, despite the potential benefits (which are likely to be minute, if any), in light of all that is unknown about taking large doses of vitamin C at the present time, the safest recommendation is to avoid vitamin C supplements and simply ride out the cold and its symptoms.












Anderson, T.W., Reid, D.B.W., and Beaton, G.H. Vitamin C and the

Common Cold: A Double-Blind Trial. (1972). Canadian Medical Association Journal,

107, 503-508.


Charleston, S.S., and Clegg, K.M. (1972). Ascorbic Acid and the Common

Cold. The Lancet, 1, 1401-1402.


Coulehan, J.L., Reisinger, K.S., Rogers, K.D., and Bradley, D.W. (1974).

Vitamin C Prophylaxis in a Boarding School. The New England Journal of Medicine,

290 (1), 6-10.


Elwood, P.C., Lee, H.P., St. Leger, A.S., Baird, I.M., and Howard, A.N.

(1976). A Randomized Controlled Trial of Vitamin C in the Prevention and

Amelioration of the Common Cold. British Journal of Preventive and Social Medicine,

30, 193-196.


Grodner, M., Anderson, S.L., and DeYoung, S. (1996). Foundations and Clinical

Applications of Nutrition: A Nursing Approach. St. Louis, MO: Mosby-Year Book,



Karlowski, T.R., Chalmers, T.C., Frenkel, L.D., Kapikian, A.Z., Lewis, T.L.,

and Lynch, J.M. (1975). Ascorbic Acid for the Common Cold: A Prophylactic and

Therapeutic Trial. JAMA, 231(10), 1038-1042.


Tyrrell, D.A.J., Craig, J.W., Meade, T.W., and White, T. (1977). A Trial of

Ascorbic Acid in the Treatment of the Common Cold. British Journal of Preventive and

Social Medicine, 31, 189-191.


Wilson, C.W.M., Loh, H.S., and Foster, F.G. (1973). The Beneficial Effect

of Vitamin C on the Common Cold. European Journal of Clinical Pharmacology, 6,






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