A controlled clinical trial of ascorbic acid for the common cold. A randomized controlled trial of vitamin C in the prevention and amelioration of the common cold. Common cold and vitamin C. The administration of large doses of ascorbic acid in the prevention and treatment of the common cold. II. Ascorbic acid for the common cold. A prophylactic and therapeutic trial. Vitamin C as a preventive medicine against common colds in children. Vitamin C and acute illness in Navajo school children. Mega-dose vitamin C in treatment of the common cold: a randomised controlled trial. Preventing the common cold with a vitamin C supplement: A double-blind, placebo-controlled survey A trial of ascorbic acid in the treatment of the common cold. Trial of ascorbic acid in prevention of colds. Winter illness and vitamin C: the effect of relatively low doses. The effectiveness of vitamin C in preventing and relieving the symptoms of virus-induced respiratory infections. Vitamin C prophylaxis in marine recruits. The beneficial effect of Vitamin C on the common cold The effects of ascorbic acid and flavonoids on the occurrence of symptoms normally associated with the common cold. Vitamin C and the common cold: a second MZ Cotwin control study.
Vitamin C has been a popular medication for preventing the common cold and reducing the severity of cold symptoms for many years . - ' Professor Pauling 's recent book on the subject has led to even further use of vitamin C in even larger doses . This study was performed to look for a difference in the frequency and severity of colds in a generally healthy , middle-class , medically aware population of employees at the National Institutes of Health . High doses of vitamin C were used for both prevention and treatment ; virus isolations were attempted in an effort to relate viral types to vitamin C response ; and the study was continued for a nine-month period in an attempt to examine seasonal variations of viruses and colds . The study was conducted so that nurses , physicians , and volunteers did not know who received placebo and who received ascorbic acid . Only the consulting statistician and the pharmacist could relate patient code numbers to medication received . Progress was monitored by a research committee not connected with the day-to-day activities A r and omized controlled trial of the effect of 1 g ascorbic acid per day in the prevention of the common cold was conducted on 688 adult women . There is evidence of a small reduction by  vitamin C  in the mean number of chest colds , but no evidence of any effect on simple colds . The existence of a subgroup of vulnerable women in the community who benefit from vitamin C was considered but further examination of the data gives no support to this conclusion Abstract The effect of daily administration of placebo or 200 or 500 mg . tablets of vitamin C on symptom association and on the incidence , duration , severity , and total intensity of the symptoms  in the common cold has been studied . The metabolism of ascorbic acid during the common cold , and after disappearance of all the symptoms , has been investigated by examining the plasma and leucocyte ascorbic-acid concentrations after a loading dose of 500 mg . vitamin C. Cold symptoms tend to dissociate into toxic and catarrhal complexes , the complexity and frequency of which differ between boys and girls .  Vitamin C reduces symptom association and alters the frequency of toxic and catarrhal complexes . It significantly reduces the severity and total intensity of colds in girls , but does not benefit cold symptoms in boys at a daily dose of 500 mg . During colds , especially of the catarrhal variety , ascorbic acid is transferred out of the leucocytes into the plasma , where it is rapidly metabolised in both sexes , but this effect is more pronounced in females . There is a significant positive correlation between metabolic utilisation of ascorbic acid during colds and intensity of cold symptoms Beginning at about the age of seven and following a tonsillectomy I began to be plagued with otitis media of which I suffered from 50 to 60 bouts over the next 20 years . These recurrent infections were treated by a series of different methods including Cubeb cigarette smoke blown into the ear by my mother , the local application of heat , sulfadiazine in nasal sprays and the earlier and later forms of injected penicillin which was useful as soon as I suffered from a sore throat if taken at the first signs of infection , but only for the secondary bacterial component of my double infection which began with a vims which appeared to pass the sentence which was executed by the bacteria . I stumbled upon the employment of ascorbic acid because of the advertisements for the bioflavonoids and vitamin C as beneficial in the prevention - and treatment of the common cold . It was apparent that the mixture diminished the symptoms of the common cold for me and for my wife , but not enough for us to continue with its employment , Would larger doses perhaps be more effective ? The doses were increased as each increment proved itself as giving better results until I reached a maximum and satisfactory effect . I did not permit myself to be dissuaded by the gloomy conclusions of others , whose work I continued to recognize had shown only that vitamin C had not been helpful against colds at the dosage used in their studies , and not the unmeasured generality that this drug had been proven utterly useless against colds . I was then able to suppress colds , at will , in five subjects . There is no doubt that we really suffered from colds during these suppressed versions of the disease , because we continued to be aware — but just aware — of whatever symptoms had been characteristic of our formerly unmodified colds . Although running of the nose would be practically non-existent , on rare occasions a single drop might appear at the nares ; however , not -a trace of " itchiness " had accompanied it in its roll down the turbinates . The thickened stage of nasal discharge was never reached . Sneezing and coughing were quite unusual . A throat did not proceed to " soreness " but , in some cases , there was a slight sensation of its presence . Hoarseness was uncommon . Headache was inconsequential . Malaise , if at all recognizable was usually so minor as to be undeserving of the name . Secondary bacterial invasions did not occur . I learned that the treatment had to be initiated early enough and needed to be continued at a high level for some time and then withdrawn or Three hundred eleven employees of the National Institutes of Health volunteered to take 1 gm of ascorbic acid or lactose placebo in capsules three times a day for nine months . At the onset of a cold , the volunteers were given an additional 3 gm daily of either a placebo or ascorbic acid .  One hundred ninety volunteers completed the study . Dropouts were defined as those who missed at least one month of drug ingestion . They represented 44 % of the placebo group and 34 % of those taking ascorbic acid . Analysis of these data showed that ascorbic acid had at best only a minor influence on the duration and severity of colds , and that the effects demonstrated might be explained equally well by a break in the double blind During 7 weeks in the spring of 1973 a double-blind pilot study on 172 children in the age group 8 - 9 was carried out to test the possible effect of 1000 mg vitamin C daily as a prophylactic agent against common colds . During the autumn of 1973 , a main study was carried out on 642 children of the same age . The investigations had the same pattern and lasted for 3 months . Both studies have been processed on the same principles . The results were somewhat divergent but , like previously published studies on children , seemed to indicate that the duration and severity of the cold were reduced while , on the other h and , the incidence remained unaltered or indeed increased . The total number of days of upper respiratory tract infection was smaller for the vitamin C group only in the pilot study ( not in the main study ) . No proven biochemical effects were obtained . Preventive treatment of healthy children with vitamin C in large doses this had no definitely proved effect against colds To evaluate earlier observations , including our own , showing usefulness of vitamin C for managing the common cold , we performed a double-blind trial of vitamin C versus placebo in 868 children . There was no difference in number becoming ill ( 133 versus 129 ) , number of episodes ( 166 versus 159 ) or mean illness duration ( 5.5 versus 5.8 days ) between the groups . Children receiving vitamin C  had fewer throat cultures yielding beta-hemolytic streptococcus ( six versus 13 , P less than 0.10 ) , but no difference in overall complicated illness rate ( 24 versus 25 ) . Plasma ascorbic acid levels were higher in the vitamin group 24 to 26 hours after supplementation ( 1.28 versus 1.04 mg per 100 ml , P less than 0.01 ) . Children with high plasma ascorbic acid concentrations had longer mean illness ( 6.8 versus 4.0 days , P less than 0.05 ) than those with low levels . Vitamin C does not seem to be an effective prophylactic or therapeutic agent for upper respiratory illness OBJECTIVE To determine the effect of large doses of vitamin C in the treatment of the common cold . STUDY DESIGN Double-blind , r and omised clinical trial with four intervention arms : vitamin C at daily doses of 0.03 g ( " placebo " ) , 1 g , 3 g , or 3 g with additives ( " Bio-C " ) taken at onset of a cold and for the following two days . PARTICIPANTS AND SETTING 400 healthy volunteers were recruited from staff and students of the Australian National University , Canberra , ACT , between May 1998 and November 1999 . The trial continued for 18 months . INTERVENTIONS Participants were instructed to commence medication when they had experienced early symptoms of a cold for four hours , and to record daily their symptoms , severity , doctor visits and use of other medications . MAIN OUTCOME MEASURES Duration of symptoms and cold episodes ; cumulative symptom severity scores after 7 , 14 and 28 days ; doctor visits ; and whether participants guessed which medication they were taking . RESULTS 149 participants returned records for 184 cold episodes . No significant differences were observed in any measure of cold duration or severity between the four medication groups . Although differences were not significant , the placebo group had the shortest duration of nasal , systemic and overall symptoms , and the lowest mean severity score at 14 days , and the second lowest at 7 and 28 days . CONCLUSIONS Doses of vitamin C in excess of 1 g daily taken shortly after onset of a cold did not reduce the duration or severity of cold symptoms in healthy adult volunteers when compared with a vitamin C dose less than the minimum recommended daily intake One hundred sixty-eight volunteers were r and omized to receive a placebo or a vitamin C supplement , two tablets daily , over a 60-day period between November and February . They 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 active-treatment group had significantly fewer colds ( 37 vs 50 , P<.05 ) , fewer days challenged virally ( 85 vs 178 ) , and a significantly shorter duration of severe symptoms ( 1.8 vs 3.1 days , P<.03 ) . Consequently , volunteers in the active group were less likely to get a cold and recovered faster if infected . Few side effects occurred with the active treatment , and volunteers reported greatly increased satisfaction with the study supplement compared with any previous form of vitamin C. This well-tolerated vitamin C supplement may prevent the common cold and shorten the duration of symptoms . Volunteers were generally impressed by the protection afforded them during the winter months and the general acceptability of the study medication A r and omised controlled trial was carried out to study the effect of 10 g of ascorbic acid taken during the first 2 1/2 days on the symptoms of the common cold . Altogether 1524 volunteers were recruited from a number of working groups in different parts of the country ; 482 developed colds . There was no evidence that upper respiratory or general constitutional symptoms were alleviated by ascorbic acid . Among the men who had any colds at all , significantly fewer on active than on placebo treatment had two or more colds ; however , this effect was not seen in women . Ascorbic acid is of no value in the treatment of the common cold ; its preventive effect , if any , is not such as to justify advising its general use as a prophylactic measure Ascorbic acid is widely used as a prophylactic and therapeutic agent against the common cold , and is in fact often recommended for this purpose by medical practitioners . It may be administered as a large dose as soon as possible after the first symptoms are felt , and this dosage is then continued for a few days in order to " abort " the cold . Though many people use this treatment on themselves and believe it is effective , it is impossible to assess its efficacy . Untreated subjects may experience symptoms such as sneezing or a mild sore throat , which then disappear without going on to a full cold , and patients ' assessment s of their colds are much influenced by any treatment owing to the placebo effect ( Diehl et a/. , 1938 ) . In these studies we attempted to show by in-vitro experiments that exposure of cells to ascorbic acid increased their resistance to infection with viruses . Though there was no activity in vitro , we also attempted to demonstrate a protective effect in ftnmy»1 « or man , since it was thought that host resistance might be enhanced indirectly After their r and om -llocation to one of three treatment aroups , 622 volunteers received either  vitamin C or placebo in a maintenance dose of 500 mg once weekly and a therapeutic dose of 1500 mg daily on the 1st day and 1000 mg on the next 4 days of any illness . Two forms of vitamin C were employed : a sustained-release capsule containing ascorbic acid and a regular tabet containing a mixture of sodium and calcium ascorbate . In the 448 subjects who completed an average of 15 weeks in the study of total of 635 episodes of illness were recroded . Respiratory symptoms were recorded on at least 1 day in 92 per cent of these episodes . There were no consistent or significant differences in the sickness experience of the subjects receiving the sustained-release vitamin capsules compared to those receiving the vitamin tablets , but subjects in both vitamin groups experienced less severe illness than subjects in the placebo group , with approximately 25 per cent fewer days spent indoors because of the illness ( P smaller than 0.05 ) . These results are compatible with the belief that supplementary vitamin C can reduce the burden of winter illness , but the intake need not be as high as has sometimes been cl aim ed BACKGROUND An ever increasing dem and to evaluate the effect of dietary supplements on specific health conditions by use of a " significant scientific " st and ard has prompted the publication of this study . OBJECTIVE To study the effect of megadose Vitamin C in preventing and relieving cold and flu symptoms in a test group compared with a control group . DESIGN Prospect i ve , controlled study of students in a technical training facility . SUBJECTS A total of 463 students ranging in age from 18 to 32 years made up the control group . A total of 252 students ranging in age from 18 to 30 years made up the experimental or test group . METHOD Investigators tracked the number of reports of cold and flu symptoms among the 1991 test population of the facility compared with the reports of like symptoms among the 1990 control population . Those in the control population reporting symptoms were treated with pain relievers and decongestants , whereas those in the test population reporting symptoms were treated with hourly doses of 1000 mg of Vitamin C for the first 6 hours and then 3 times daily thereafter . Those not reporting symptoms in the test group were also administered 1000-mg doses 3 times daily . RESULTS Overall , reported flu and cold symptoms in the test group decreased 85 % compared with the control group after the administration of megadose Vitamin C. CONCLUSION Vitamin C in megadoses administered before or after the appearance of cold and flu symptoms relieved and prevented the symptoms in the test population compared with the control group A prospect i ve , r and omized , double-blind study was carried out to determine whether vitamin C prophylaxis , 2.0 g/day , vs placebo prophylaxis would reduce the incidence or morbidity of the common cold  and other respiratory illnesses in 674 marine recruits during an eight-week period . Whole-blood ascorbic acid levels measured six weeks after initiation of the study were significantly higher in the vitamin C group . There was no difference between the two groups in the incidence or duration of colds . The vitamin C group rated their colds as being less severe , but this was not reflected in different symptom complexes or in fewer sick-call visits or training days lost . This study and the literature do not support the prophylactic use of vitamin C to prevent the common cold Summary The occurrence of common cold symptoms was recorded daily for a period of nine months by children from two male and two female boarding schools . All the children in one male and one female school received tablets containing 200 mg Vitamin C , or placebo tablets , daily on a double blind basis . Children in the other two schools received 200 or 500 mg tablets of Vitamin C.  Leucocyte ascorbic acid concentrations were significantly raised in those children receiving active tablets . Comparisons of incidence , duration , severity and total intensity of cold characteristics , and of cold frequencies , were made between the different treatment groups . Cold symptoms were grouped into those characteristic of Catarrhal ( C-colds ) , and those of Toxic ( T-colds ) , colds . Whole ( W-colds ) consisted of at least one C-symptom in combination with one or more T-symptoms . 200 mg of Vitamin C had a beneficial effect on severity and total intensity of C- and W-colds , but did not affect T-colds , in girls . 500 mg produced further slight beneficial effects . With 200 mg the cold categories in boys tended to show a deterioration , and the deterioration continued in the group receiving 500 mg . Analysis of cold frequency indicated that T-colds are commoner in girls . Their C-cold frequency diminished with the smaller dose , and their T-cold frequency was reduced by the larger dose of Vitamin C. In boys C-cold frequency diminished with 500 mg of Vitamin C daily . These data suggest that there is a sexual difference in the effects of Vitamin C on the characteristics of the common cold . Evaluation of the effects of Vitamin C on toxic and catarrhal symptoms in relation to administered doses is of more importance than examination of its prophylactic or therapeutic actions . 500 mg had some beneficial effect in girls : any beneficial effect of Vitamin C on the common cold in boys will probably be associated with administration of a higher daily dose A controlled study was made of the effects of natural orange juice , synthetic orange juice , and placebo in the prevention of the common cold ; both natural and synthetic orange juices contained 80 mg of ascorbic acid daily . Three-hundred sixty-two healthy normal young adult volunteers , ages 17 to 25 years , were studied for 72 days with 97 % of participants completing the trial . There was a 14 to 21 % reduction in total symptoms due to the common cold in the supplemented groups that was statistically significant ( P less than 0.05 ) . Ascorbic acid supplementation also increased the number of " episode-free " subjects . However , the clinical usefulness of the results does not support prophylactic ascorbic acid supplements in the well-nourished adult . The results in this study with both natural and synthetic orange juice of physiological content of ascorbic acid , are similar to those obtained using a " megadose " of ascorbic acid Self-reported cold data have been analyzed for 95 pairs of identical twins aged 14 - 64 who took part in a double-blind trial of vitamin C tablets .  One member of each twin pair took a tablet containing 1 g vitamin C and the other took a well-matched placebo each day for 100 days . In the total sample there was no effect of vitamin C in preventing colds . However , subdivision of the data showed a significant preventive effect of the placebo in the 51 pairs living together and an equal and opposite preventive effect of the vitamin C in the 44 pairs living apart . The placebo effect in the pairs living together may be attributed to the large proportion who wrongly perceived which treatment they were taking . The reduction of colds in the vitamin C group of the pairs living apart was about 20 % . There were significant correlations between cold symptoms reported and the personality trait of neuroticism . No side effects of substantive changes in serum biochemistry could be attributed to the vitamin C dose
REVIEW ERS ' CONCLUSIONS The failure of vitamin C supplementation to reduce the incidence of colds in the normal population indicates that routine mega-dose prophylaxis is not rationally justified for community use .
But evidence shows that it could be justified in persons exposed to brief periods of severe physical exercise and /or cold environments .
Also , the consistent and statistically significant small benefits on duration and severity for those using regular vitamin C prophylaxis indicates that vitamin C plays some role in respiratory defence mechanisms .
BACKGROUND The role of oral vitamin C ( ascorbic acid ) in the prevention and treatment of the  common cold  has been a subject of controversy for at least sixty years .
Public interest in the topic continues to be high and vitamin C continues to be widely sold and used as a preventive and therapeutic agent for this common ailment .
OBJECTIVES To discover whether oral vitamin C in doses of 200 mg or more daily , reduces the incidence , duration or severity of the common cold when used either as continuous prophylaxis or after the onset of cold symptoms .