Scand J Infect Dis 9:91-98, 1977Vitamin C as a Preventive Medicine against CommonColds in ChildrenJOHNNY LUDVIGSSON, LARS OLOF HANSSON and GUNNAR TIBBLINGFrom the Departments of Paediatrics and Clinical Chemistry, Linkoping University, Linkoping, SwedenABSTRACT. During 7 weeks in the spring of 1973 a double-blind pilot study on 172 children inthe age group 8–9 was carried out to test the possible effect of 1000 mg vitamin C daily as aprophylactic agent against common colds. During the autumn of 1973, a main study was carriedout on 642 children of the same age. The investigations had the same pattern and lasted for 3months. Both studies have been processed on the same principles. The results were somewhatdivergent but, like previously published studies on children, seemed to indicate that the durationand severity of the colds were reduced while, on the other hand, the incidence remained unalteredor indeed increased. The total number of days of upper respiratory tract infection was smaller forthe vitamin C group only in the pilot study (not in the main study). No proven biochemical effectswere obtained. Preventive treatment of healthy children with vitamin C in large doses thus had nodefinitely proved effect against colds.INTRODUCTIONEarlier studies (24, 25, 31) on the effects of vitaminC on common colds have led to varying conclu-sions. Since Linus Pauling stated that there wassufficient proof of the good effects of vitamin Cagainst common colds (20, 21, 22), the interest invitamin C's possible effects in this connection hasagain increased. Several researchers have thoughtthat they could confirm an effect of vitamin Cagainst upper respiratory tract infection at largedoses (1, 2, 3, 6, 8, 12, 32, 33, 34, 35), while othershave not found such an effect (4, 5, 26). The resultshave, however, been difficult to interpret, andfurther studies are called for (36, 37, 38). For thatreason a study was carried out in 1973 on schoolchildren in Linkoping on the questions: "Has vita-min C in large doses any preventive effect againstcommon colds in children?", and "Is it possible toestablish any biochemical effects from such ad-ministration?"SUBJECTS AND METHODSThe investigation consisted of a pilot study and amain study. The pilot study took place over 7 weeksMarch-April 1973 at 2 schools in Linkoping, situated in adistrict with many children and known to be high in fre-quency of infections. Ten classes in form 2-3 took part. Of207 pupils asked, 172 took part from the start, and of those158 completed the investigation (Table I). Then the mainstudy was carried out during September-December 1973along the same lines. Of 92 classes in forms 2–3 in Linkop-ing which had not taken part in the pilot study, 50 werechosen at random. Of these 36 took part, while in theremaining 14 classes the teachers either would not orcould not participate. The classes belonged to 15 schoolsspread all over Linkoping. Of 719 pupils asked, 642 tookpart, and of those 615 completed the study (Table I). Inboth studies, permission was obtained from the schoolauthorities, teachers and representatives of the health au-thorities. All school children and teachers were informedorally by the authors on the layout of the study and itsaim. The children's parents were informed by letter andalso had to give their written consent to the children'sparticipation. The parents also gave information on anyillnesses of their children such as allergies, asthma, dia-betes mellitus, kidney disease and other illnesses. Infor-mation was also obtained on the number of siblings andthe degree of daily contact with infants. Children fromvegetarian families were excluded.Every class was divided at random into two groups.Background variables were divided at random so that thegroups became nearly identical (Table II). In one of thegroups the children received daily a fizzy tablet whichcontained 1000 mg vitamin C; in the other group the fizzytablet looked and tasted the same but contained 30 mgvitamin C in the spring study and 10 mg in the autumnstudy. The fizzy tablets were handed out on school daysby the teachers, dissolved in water and taken by all duringone of the first lessons of the day. On other days, i.e.holidays, weekends and days off sick, the children's fizzytablets were given in the home. The children were told (byScand J Infect Dis 992 J. Ludvigsson et al.Table I. Sex and age compositions of various vitamin C dosage groupstheir parents as well) not to eat any other vitamin tabletscontaining vitamin C during the test.Both studies were carried out totally double blind.Teachers and parents noted on special forms in parallelthe occurrence of various cold symptoms, other illnessesand any absence from school (Table III). Some variableswhich were used in the pilot study gave so little informa-tion that they were not used in the main study. Theteachers' notes were supplemented by those made by theparents, whereupon the information was collated, thecode used decoded and the material processed statistical-ly.1 As the basis of the statistical processing the followingfirm definitions were made of the different infection vari-ables which parents and teachers had noted:(a) Cold symptoms from the nose (runny nose and/orsneezing and/or stuffed nose), sore throat and cough: Thenumber of days with a cold were counted as a continuousperiod if they were noted down as symptom-free for up toa maximum period of 2 days at a time.(b) Temperature from upper respiratory tract infectionor from other illness, general symptoms (i.e. "feelingbad", "muscle ache", "heaviness in the head"): Only daysnoted as with symptoms were counted, i.e. the 2-daysymptom-free were not counted.(c) Upper respiratory tract infection: A continuousperiod, including up to 2 days symptom-free, showing thefollowing symptoms: Runny nose, stuffed nose or sneezing + cough, sore throat, general symptoms, temperatureor absence from school because of infection in upperrespiratory tract.(d) Active infection in upper respiratory tract: A continuous period, including up to 2 days symptom-free, during which at least 2 symptoms of upper respiratory tractinfection (see above) have been noted occurring together.In a continuous upper respiratory tract infection, however, the occurrence of "active upper respiratory tractinfection" is not counted as more than one period.1 Statistical calculations were carried out by Mr LarsLindvall, Institute of Mathematics, Linkoping University.(e) Upper respiratory tract