VITAMIN C AND THE COMMON COLD
Te ence W. Ande son, M.D., Ph,D.
P o esso o Epidemiology
Dep . o P e en i e Medicine
and Bios a is ics Facul y o
Medicine Uni e si y o To on o
To on o, On a io, Canada
The idea ha an inc eased in ake o
i amin C may be help ul in igh ing
he common cold has been a ound
since a leas he 1930's bu i was no
un il 1970 ha he publica ion o Linus
Pauling's bes selle , "Vi amin C and
he Common Cold," u ned he issue
in o a public con o e sy (1). Fo u-
na ely, as a esul o he in e es
gene a ed by his con o e sy, a
numbe o scien i ically sound expe i-
men al s udies ha e been ca ied ou
and al hough he e a e s ill ques ions
ha emain unanswe ed, i is now
clea ha i amin C is, un o una ely,
no panacea o colds o o he espi a-
o y in ec ions
Howe e , e en i he p omise o
i ual e adica ion o he common
cold (sugges ed as a possibili y a one
poin in Linus Pauling's book) has
p o ed o be un ealis ic, he e emains
enough in iguing e idence o some
in e ac ion be ween his i amin and
he in ec ious p ocess o sugges ha
i is wo h in es iga ing u he and
ha i may ha e a ole, howe e
limi ed, in educing he bu den o his
ela i ely i ial bu annoying a lic-
ion,
P e en ion o T ea men ?
In ying o un a el some o he
con usion and con lic ing e idence
o e he use o i amin C in uppe -
espi a o y in ec ions, i is help ul o
ecognize ha i s use has been
sugges ed ei he o p e en he dis-
ease om occu ing o o ea i once
i has occu ed. These a e wo qui e
di e en app oaches and ca y wi h
hem di e en p ac ical implica ions.
Thus, i i amin C is o be used
p ophylac ically in an e o o p e-
en he common cold, no only is one
aced wi h he p oblem o compliance
(many people will no be bo he ed
wi h aking egula medica ion when
ee o symp oms) bu also wi h an
inc eased possibili y o side e ec s
since hese a e mo e likely o occu
wi h some hing ha is aken egula ly
o mon hs o yea s han wi h
some hing ha is used only
occasionally and b ie ly as a
ea men .
Simila ly, wo o he issues o which
indi iduals o en lose sigh in he
he o ic a e he ques ions o e ec i e
dose and he basic nu i ional s a us o
he popula ion. Thus, i a daily in ake
o 1000 mg o i amin C is ound o
p oduce a bene icial e ec , i is
impo an o es ablish whe he he
same e ec could be achie ed wi h a
much smalle dose since undesi able
side e ec s a e mo e likely om la ge
doses han small ones. Fu he ,
wha e e size dose is aken, i is only
likely o show an e ec in a popula ion
ha has oom o imp o emen - in
o he wo ds, well-nou ished indi id-
uals a e likely o be poo expe imen-
al subjec s o demons a ing an
e ec o supplemen al i amin C.
So a , ew o he expe imen al
s udies ha ha e been ca ied ou
ha e shown much change in
p e en i e e ec om he egula in-
ake o la ge doses o i amin C. E en
whe e he e seems o ha e boon some
e ec , i is p obably maximal a in-
akes p oducing "sa u a ion" In no -
mal heal hy subjec s, his is achie ed
a abou 100-150 mg o i amin C daily
bu he amoun needed may be
conside ably inc eased by acu e o
ch onic illness and a imes o en i on-
men al s ess. Examples o he la e
a e ex eme cold and physical
exe ion and i is o in e es ha wo o
he ew posi i e s udies on egula
in ake o i amin C ha e in ol ed
people in hese ci cums ances: one
in ol ing s uden s a a skischool in he
Swiss moun ains (2), he o he
in ol ing Canadian A my oops in
A c ic exe cises (3)
In ela i ely a luen u ban subjec s,
i has been di icul o demons a e
much
bene i om he consump ion
o g am quan i ies o i amin C ei he
on a p ophylac ic o he apeu ic basis
Recen s udies ha e been
e iewed by
Chalme s (4) and Dykes (5)
In ou own s udies in To on o, we
ound li le e ec om he pu ely
p ophylac ic egimens wi h no
e idence o a g adien in e ec ac oss
he dosage ange o 250, 1000 o 2000
mg pe day (6). Indeed, he only
imp essi e di e ences ha we ha e
seen in ou expe imen al g oups ha e
been w i h a combina ion o
p ophylac ic and he apeu ic
egimens (6, 7, 8). E en in hese
g oups, he e was li le o no e idence
o an e ec on he equency o colds,
upon hei o al du a ion o upon local
(nasal) symp oms. Ra he , he e ec
seemed o be es ic ed o he se e i y
o he cold as measu ed by he amoun
o ime spen o wo k o con ined o
he house. These esul s a e
summa ized in Figu e 1.
Summa y diag am o he esul s o
h ee la ge-scale ials o he e ec o
i amin Con he common cold. On he
e ical scale, he expe ience o he
i amin g oup is exp essed as a
pe cen age o placebo g oup.
On he le -hand side o he
diag am is seen he lack o any
consis en dose- esponse g adien
when using h ee d i e e n
dosages o egula (p ophylac ic)
in ake only On he igh -hand side is
shown he esul s o using
combina ion p ophylac ic and
he apeu ic egimens. Wi h all h ee
combina ions, he g ea es e ec was
seen on disabili y (days spen
indoo s) while he numbe o episodes
and days o nasal symp oms showed
li le o no e ec
Resul s o 1972 s udy (7) shown by
c osses, he 1971 s udy (6) by squa es,
he 1975 s udy (8) by ci cles,
1292 New Yo k S a e Jou nal o Medicine/July 1979
The he apeu ic alue o i amin C
in la ge doses has ecei ed
s ong, anecdo al suppo . Fo
example, I win S one has claimed ha
o e 95% o colds can be abo ed by
he p omp adminis a ion o
app oxima ely 1.5 g o i amin C e e y
hal hou o h ee o ou doses (9). I
some indi iduals ha e eally
expe ienced his so o esponse,
hen one mus conside he possibili y
ha he e is a subg oup o he
popula ion o whom i amin C is
e ec i e; whe eas, o he emainde ,
i is ela i ely (o comple ely) ine ec-
i e since la ge-scale con olled ials
ha e been qui e unimp essi e (10,11).
In summa y, one may a emp o
econcile he con lic ing e idence by
sugges ing ha inc eased in ake o
i amin C on a egula basis o a he
ime o illness may exe a sligh
bene icial e ec , mo e ma ked when
he wo egimens a e combined. The
size o he e ec p obably a ies
be ween indi iduals — wi h many
being ela i ely insensi i e — and i
will also a y acco ding o basic
nu i ional s a us, gene al s a e o
heal h and exposu e o en i onmen al
o o he s ess.
Mechanism
Some in es iga o s ha e concluded
ha al hough he e may be a sligh
e ec o i amin C on he common
cold, i is oo small o be o any
p ac ical alue and he subjec is,
he e o e, no wo h pu suing. Bu his
may be somewha sho -sigh ed since
i is possible ha i we ully unde s ood
he mechanism in ol ed in p oducing
e en a sligh e ec , we migh be able o
de elop i u he and p oduce e ec s
ha we e quan i a i ely mo e
wo hwhile. As i is, e y li le is known
abou he mechanisms ha migh be
in ol ed in in e ac ions be ween i a-
min C, he common cold and a num-
be o o he disease p ocesses (12).
Some ha e sugges ed ha he e
may be a ype o an ibio ic e ec in
which high concen a ions o asco -
bic acid ha e a speci ic an i- i al o
an i-bac e ial e ec . Human expe i-
men s ha e no len much suppo o
his belie al hough i i we e ue, one
would expec o see a ia ion in
e ec i eness depending on he ype
o i us o bac e ium causing he
illness and such a ia ion migh help
o explain some o he con lic ing
esul s ob ained in i amin C ials.
Ano he possibili y is ha i amin C
has a ype o an ihis amine e ec and
al hough he e is some expe imen al
e idence o suppo his iew, in ou
s udies we saw li le e idence o a
educ ion in nasal i i a ion o s u i-
ness.
A hi d possibili y and he one ha I
ind he mos c edible is ha any e ec
o i amin C is ia he hos esis ance
o in ec ion. This would be consis en
wi h animal expe imen s hai ha e
shown an imp o ed esis ance 1o
s ess and wi h ou own expe ience o
a educ ion in gene al cons i u ional
symp oms ("malaise"). I would also
be consis en wi h he high concen a-
ion o i amin C no mally ound in he
ad enal co ex and i s deple ion a
imes o s ess
Toxici y
The e ha e been i ually no docu-
men ed ins ances o se ious oxic
eac ions o i amin C e en when
used in e y la ge doses. This is
no al oge he su p ising since i is a
subs ance essen ial o li e and one o
which we and ou ances o s ha e been
exposed o millions o yea s. How-
e e , i is as well o emembe ha
none o ou ances o s could ha e been
exposed o he quan i ies ha a e
now easily a ailable as a esul o he
p oduc ion o he pu e subs ance and
al hough i is a e y simple molecule
(simila o glucose), i is a s ong
educing subs ance, an acid, and is
biologically e y po en . The e o e, i
is impo an o be cau ious in i s use.
The e a e a numbe o di e en
ways, in heo y a leas , in which
undesi able e ec s migh occu . Fi s ,
as an acid, la ge doses could p ecipi-
a e acid s ones in he u ine and as a
educing subs ance, i amin C could
in e e e wi h some o he common
diabe ic u ine es s. Second, in
suscep ible indi iduals, i could ha e
unusual me abolic e ec s (a g ea ly
inc eased ou pu o oxala e is one ha
has been iden i ied), which a e
ex emely di icul o de ec since
hey may be oo a e o be ecognized
e en in la ge-scale s udies. Thi d, a
po en ially ha m ul eac ion is he
wi hd awal e ec on blood le els
when cu ing back a e p olonged
in ake o la ge doses. Blood le els o
he asco ba e ion each a pla eau
("sa u a ion") a an In ake o 100-150
mg pe day and he in ake o e en
se e al housand millig ams a day
does no g ea ly change his pla eau
le el. Howe e , i a e a ew weeks
o high in ake ho ex a in ake is
s opped, blood le els can d op well
below no mal o se e al days.
Whe he his has any physiological
signi icance is no known bu i is
possible ha i i occu ed a he same
ime as a se ious illness ( o example,
on admission o a hospi al wi h a hea
a ack), i could handicap he body's
a emp s o deal wi h he ex a s ess.
Summa y
Ca e ully con olled expe imen al
s udies ha e ailed o suppo claims
ha he in ake o la ge doses o
i amin C will p e en o cu e he
majo i y o colds. Howe e , an in-
c eased egula in ake o a la ge
he apeu ic dose a he ime o illness
may ha e a small bene icial e ec and
his e ec appea s o be on se e i y
a he han equency o o al du a ion
o colds. The magni ude o he e ec
p obably a ies be ween indi iduals,
in di e en en i onmen s and possi-
bly acco ding o he ype o in ec ing
agen . The use o e y high doses o
i amin C migh be ha m ul o some in-
di iduals, pa icula ly i he in ake is
p olonged. Howe e , o mos people,
a modes inc ease in he egula daily
in ake o b ie episodes o high in ake
a e unlikely o cause ha m and may
imp o e esis ance o o he ypes o
illness, no only he common cold.
Re e ences
1.
Pauling. L, Vi amin C and he
Common Cold, W.H. F eeman,
San F ancisco, 1970.
2. Ri zel, G., Hel . Med. Ac/a. 28:63.
1961.
3. Sabis on, B.H., Radomski, M.W.,
D.C.I.EM Repo No. 74-R-1012,
De ence Resea ch Boa d, Cana
da, 1974.
4. Chalme s, T.C., Am. J. Med. 58:
532, 1975.
5. Dykes, M.H.M., Meie , P.. JAMA
231:1073, 1975.
6. Ande son, T.W..Su anyi,G., Bea
on, G.H., Can. Med. Assoc. J. 111:
31,1974.
7. Ande son, T.W., Reid, D.B.W..
Bea on, G.H., Can. Med. Assoc J.
107:503,1972.
8. Ande son, T.W., Bea on, G.H.,
Co ey, P.M., Spe o, L., Can. Med.
Assoc. J. 112:828, 1975.
9. S one. I., Nu i ion Today 10:3:35,
1975.
10. Elwood, P.C., Hughes, S.J., S .
Lege , A.S., P ac i ione 218:133.
1977.
11. T y e l l , D.A.J., C aig, J.W.,
Meade. T.W., While, T., B . J. P e .
Soc. Med. 31:189. 1977.
12. Ande son, T.W., Nu i ion Today
12:1:6,1977.
Rep in ed om Com empo a y Nu i ion, Gene al Mills, Inc., Oc obe , 1978, Volume 3, Numbe 10.
July 1979/New Yo k S a e Jou nal o Medicine 1293
