Date Last Updated: 11/04/06
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Does Vitamin C treat or
prevent the common cold?
Treatment in brief
Vitamin C (ascorbic acid).
The Common Cold
The common cold is a mild viral infectious disease of the nose and throat.
Its symptoms include sneezing; sniffing; a runny or blocked nose; scratchy,
sore or phlegmy throat; coughing; headache and a general feeling of
unwellness. It will generally last between 3 and 10 days, with residual
coughing lasting up to 3 weeks.
Background
The common cold is the leading
cause of illness and the main reason for visits to a doctor in Western
countries. It is also a major cause of absenteeism from work and school.
The role of oral vitamin C in the
prevention and treatment of the common cold has been a subject of argument
for at least sixty years. Vitamin C is sold widely for the prevention and
treatment of colds.
Since the early 1940s, a large
number of studies have examined the possible effects of vitamin C on the
common cold.
This report looks at taking
vitamin C:
The Evidence
Treatment
There is level 1 evidence from eleven studies in a systematic
review that the duration or severity of cold symptoms is not reduced if
vitamin C is taken when cold symptoms start.
Prevention
-
There is
level 1
evidence from twenty-nine studies that regularly taking vitamin
C does not reduce the number of common colds occurring in the ordinary
population.
-
There is
level 1
evidence from six studies that regularly taking vitamin C reduces
the risk of developing a cold by half in people exposed to short periods
of extreme physical and/or cold stress (including marathon runners and
skiers).
-
There is
level
1 evidence from forty-five studies that regularly taking
vitamin C reduces the duration and severity of common cold symptoms.
However, the size of the effect was small and this raises doubt about
its real usefulness.
Other
Important Issues
The small reduction in
the duration of the symptoms of a cold in adults (8%) and children (13.6%)
may not justify taking vitamin C as a long-term preventative due to the
ongoing cost. This means that if a cold normally lasted 10 days then the
duration of the cold would be reduced by almost one day if you were an adult
and one and a half days if you were a child.
In seven large studies, the
number of adverse effects reported was similar in the vitamin C
group and the placebo group. This suggests that the adverse events were not
caused by taking vitamin C. However, no serious adverse effects were
reported. For more information on possible adverse effects see
http://1stholistic.com/Nutrition/hol_nutr-toxic-dosages.htm
Regular dietary intake of vitamin
C from fruit and other sources is highly variable and despite this intake
was not measured in most of the studies.
None of the studies that used vitamin C as a
treatment after symptoms of a cold had started was carried out in children.
Key Messages
Treatment
|
There is
evidence that taking vitamin C does not reduce either the
duration or severity of cold symptoms. |
1 |
|
|
|
Prevention
|
There is
evidence that regularly taking vitamin C does not reduce the
number of common colds occurring in the ordinary population. |
1 |
|
There is
evidence that regularly taking vitamin C does reduce the risk of
developing a cold in people exposed to short periods of extreme physical
and/or cold stress. |
1 |
|
There is
evidence that regularly taking vitamin C does reduce the duration
and severity of common cold symptoms. |
1 |
|
|
|
Key:
Levels of
evidence
The information in this
summary was developed by assessing:
The Cochrane
review: Vitamin C for preventing and treating the common cold. 2004
http://www.mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD000980/frame.html
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