Advances
In Therapy®
Advances In Natural Therapy™
Volume 19 No. 3
May/June 2002
Preventing the Common Cold
With a Vitamin C Supplement:
A Double-Blind, PlaceboControlled Survey
Michael Van Straten
Peter Josling, B.Sc. Hons.
Herbal Health Centre
Battle, East Sussex
United Kingdom
ABSTRACT
One hundred sixty-eight volunteers were randomized 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.
Keywords: common cold; vitamin C
INTRODUCTION
The common cold is the world’s most widespread viral infection, with
most people suffering approximately two to five colds per year.1 Over 200
different viruses cause infection and cold symptoms; the most common,
rhinoviruses, account for 30% to 40% of adult colds. Re-infection is prevalent because of the many varieties of infectious viruses.1
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Mr. Peter Josling
Herbal Health Centre
Battle, East Sussex, United Kingdom
151
Consumers are often encouraged to take large doses of vitamin C supplements to
prevent or relieve symptoms of the common cold,2-4 although researchers disagree
on the efficacy of taking any vitamin C preparation for either purpose. In fact, the
most recent research suggests that vitamin C has no particular benefit over a placebo,5,6 particularly if the “window of opportunity” is missed.
The purpose of this double-blind, placebo-controlled survey was to ascertain
whether a specific form of vitamin C could offer a degree of prevention when used
throughout the winter months rather than when used once an infection had begun.
The active preparation was Ester-C ascorbate, a natural form of vitamin C that allows
cells to efficiently absorb and retain high levels of the vitamin. It is postulated that
rapid cellular absorption and delayed renal excretion of ascorbic acid maximize its cellular concentration to provide high levels of biochemical activity7 and strengthen the
immune system, rendering it less likely to suffer during viral challenge.
A “cure” for the common cold would substantially reduce the number of work days
lost each year as a result of symptoms of infection including tiredness, headaches,
runny nose, sneezing, coughing, watery eyes, and impaired concentration.
The many vitamin C supplements marketed in the United Kingdom, United
States, and Europe vary widely by type and recommended dietary allowance.
Increasing evidence has shown that Ester-C ascorbate may have significant beneficial properties, because the ascorbate is readily used by white blood cells, potentiating immune cell function.8
METHODS
One hundred sixty-eight participants were recruited through an editorial in the
consumer media. A diary was designed in which volunteers recorded general wellbeing for 60 days on a five-point scale (5 = well, no problems; 4 = quite well with
occasional sneeze, not disruptive to normal routine; 3 = can feel a cold coming on,
some minor symptoms; 2 = feeling low and beginning to exhibit symptoms; 1 = full
cold symptoms [headache, sneezing, runny nose, sore throat, cough, tiredness]) and
assessed the number and severity of coughs and colds experienced during the trial
period. This scale has been used previously to assess the degree and severity of cold
symptoms.9 If a cold occurred, volunteers noted the number and variety of symptoms, the day recovery began, and the day they felt completely better.
Volunteers were separated into two groups of 84 participants (Table 1). A simple
random number generator assigned volunteers to the active or placebo group, and
they were instructed to take two tablets (Ester-C ascorbate 500 mg or a matched
placebo) every day with their main meal, according to the manufacturer's recommendation. General dietary habits were determined before the study, and volunteers were told not to make any dramatic changes. Individuals who had already
received an influenza inoculation were excluded from the statistical analysis, as
were those who were currently taking a vitamin C product.
Randomization codes were kept secure and were not broken until all the survey
data had been returned. The Herbal Health Centre contacted volunteers at random
every 2 weeks to ensure that tablets were being consumed correctly and that any
infection was recorded appropriately. A subset of 104 volunteers completed a questionnaire designed to ascertain their personal circumstances and provide a subjective
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M. Van Straten, P. Josling
Preventing the Common Cold
evaluation of the quality and acceptability of the treatment they received (Appendix).
The remaining 64 participants were instructed to record comments and observations
in the diary.
Table 1. Demographics
Characteristic
Active Treatment
Placebo
(n=84)
(n=84)
Men
15
12
Women
69
72
Mean age, y
47.7
48.5
Previous use of vitamin C supplements, no.
48
56
This double-blind survey used a matched placebo control that looked and tasted
exactly the same as the active material. Both compounds were supplied in plain
white bottles, and volunteers were told to take two 500-mg tablets every day at
the same time, preferably with food, during a 60-day period between November and
February. A tablet count at the end of the survey indicated compliance.
Data Analysis
After diaries were returned, the number of colds experienced by volunteers was
counted. A cold was defined as a score of 3 that proceeded to 2 or 1, with symptoms.
The duration of symptoms was the number of days with a recorded score of 2 or 1,
leading to an average recovery time that ended with a score of 4 or 5 taken across all
recorded colds. The number of days on which infected volunteers recorded a score of
1 was further analyzed to identify any difference in duration of full cold symptoms.
The number of coughs, colds, and other symptoms was noted, as was the overall
incidence of adverse events, which included heartburn, indigestion, and stomach
upsets. Volunteers also recorded other concerns—acceptability of taking tablets, side
effects such as odor, or other reasons that might warrant discontinuation of treatment—and telephoned the Herbal Health Centre for further advice. Volunteers
compared their subjective experience during this winter period with previous years
and were asked whether they would continue taking the compound and recommend it to a friend (see Appendix for results).
Statistical Analysis
The average symptom length in days and the total number of colds per group were
subjected to calculations of standard deviation, sample variance, and standard error of
the difference of the means. Data were analyzed by means of a Student’s t test to gain
a probability coefficient allowing for the calculated number of degrees of freedom.
Advances In Therapy®
Volume 19 No. 3, May/June 2002
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RESULTS
Two participants withdrew from the study for personal reasons, but at the end
of the 60-day period, 37 colds were recorded in the active group and 50 colds in
the placebo group (P<.05 in favor of the supplement as a cold preventative).
The placebo group recorded an average of 3.1 days with a symptom score of
1 (178 days of infection/50 colds), ie, fully infected with multiple symptoms, compared with only 1.8 days (85/37) in the active group (P<.03) (Table 2).
Table 2. Total Number of Colds and Prevalence of Full Cold Symptoms
Characteristic
Average duration of symptoms, d
Sample variance
Standard deviation
Active Treatment
1.8
6.7
2.98
Standard error, difference of means
Student’s t distribution
Degrees of freedom
Probability
P<.03
Total number of colds
Sample variance
Student’s t distribution
Probability
37
5.25
.375
P<.05
Placebo
3.1
23.78
4.65
3.6
156
50
6.05
During the study, 16 volunteers taking the placebo became reinfected (experienced more than one full-blown cold); only 2 volunteers taking the active supplement had a reinfection.
The overall incidence of side effects was low. Indigestion was most common in
the placebo group at 10%, compared with 4% in the active group. Respective incidences of heartburn were 4% and 7%. These percentages are far lower than previously reported by volunteers who had taken ordinary ascorbic acid supplements in
the past, indicating greater tolerability of the study preparation (see Appendix).
The subset of 104 volunteers reported a 77% reduction in the number of coughs compared with previous winters. Moreover, 85% of respondents in the active group would
continue taking the compound, and 81% would recommend it to friends and family.
Perhaps not surprisingly, 64% of the active group felt “better” or “much better” during
the trial.
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Preventing the Common Cold
DISCUSSION
This study is the first to use a double-blind, placebo-controlled design to investigate
prevention of a viral disease with a vitamin C supplement. The results favor the supplement as a preventive measure, demonstrating accelerated relief, reduction in the
severity of troublesome symptoms such as sneezing, cough, and runny nose, recovery
to full fitness, and a small but significant reduction in the total number of colds.
Of particular note is that volunteers in the active group who contracted a cold
showed a reduction in the time to begin recovery and to relieve symptoms. A difference of just over 1 day is of the same order of magnitude that could be reasonably
expected from pharmaceutical or over-the-counter medications.
This study suggests that the vitamin C supplement evaluated may offer significant benefits over ordinary ascorbic acid or vitamin C. Although claims of a “cure”
for the common cold are unwarranted, the results support prevention of infection as
well as a faster recovery with Ester-C ascorbate compared with placebo.
Large numbers of individuals are at particular risk during the winter, and the
incidence of “summer colds” continues to increase. Daily use of Ester-C ascorbate
throughout the year may substantially reduce the number of infectious incidents
suffered by the working population and lead to potential savings in terms of
decreased sick days. Ester-C ascorbate warrants further investigation to determine
the precise nature and method of its antiviral activity.
ACKNOWLEDGMENTS
We thank all the volunteers and are grateful to Debbie Murphy for her excellent
administrative assistance. The Ester-C and matched placebo tablets were provided
by the Inter-Cal Corporation, Prescott, Arizona, USA.
REFERENCES
1. Eccles R. Common Cold Centre, Cardiff, UK. Available at: http://www.cf.ac.uk/biosci/associates/
cold/home.html.
2. Hemila H. Vitamin C intake and susceptibility to the common cold. Br J Nutr. 1997;77:59-72.
3. Hemila H. Vitamin C and common cold incidence: a review of studies with subjects under
heavy physical stress. Int J Sports Med. 1996;17:379-383.
4. Hemila H. Vitamin C and the common cold. Br J Nutr. 1992;67:3-16.
5. Hemila H, Herman ZS. Vitamin C and the common cold: a retrospective analysis of Chalmers’
review. J Am Coll Nutr. 1995;14:116-123.
6. Audera C, Patulny R, Sander B, Douglas R. Mega-dose vitamin C in treatment of the common
cold: a randomised controlled trial. Med J Aust. 2001;175:359-362.
7. Bush MJ, Verlangieri AJ. An acute study on the relative GI absorption of a novel form of calcium
ascorbate. Res Commun Chem Pathol Pharmacol. 1987;57:137-140.
8. Fay MJ, Verlangieri AJ. Stimulatory action of calcium threonate on ascorbic acid uptake by
a human T-lymphoma cell line. Life Sci. 1994;49:1377-1381.
9. Josling PD. Preventing the common cold with a garlic supplement: a double-blind placebocontrolled survey. Adv Ther. 2001;18:189-193.
Advances In Therapy®
Volume 19 No. 3, May/June 2002
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Appendix
A subset of 104 volunteers answered a series of questions designed to provide
personal details, a subjective assessment of the relative merits of treatment, and perceived improvement during survey period. A pretrial questionnaire was used. After
the survey was completed and the volunteers had been unblinded, a posttrial
assessment was undertaken.
At Registration
Active
Treatment
Placebo
Average age of participants, y
47.4
49.2
Are you receiving medical
treatment or taking any
long-term medication at
the moment? (%)
Yes
No
20.0
80.0
20.0
80.0
Question
Pretrial Questionnaire
Question
Which best describes your usual state
of health? (%)
I am very healthy
I am reasonably healthy but could be better
Sometimes healthy, sometimes not
I am unwell, ill, in poor health
Do you smoke cigarettes? (%)
No
Yes
On a normal day, how many cigarettes
do you smoke? (%)
Fewer than 4
5–14
15–20
20+
Active
Treatment
Placebo
36
58
4
2
24
63
9
4
90
10
89
11
20
60
20
0
50
16.67
16.67
16.67
Continued
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M. Van Straten, P. Josling
Preventing the Common Cold
Pretrial Questionnaire (cont’d)
Question
Do you drink alcohol? (%)
No
Yes
Active
Treatment
31
69
Placebo
19
81
Average alcohol consumption per week, units
6.4
5.4
Average portions of fruit and vegetables eaten
per day
3.6
3.5
Average number of infections in normal year
3.16
3.2
Of these episodes, how many times do you catch
A cold
A cough
Flu
2.6
1.24
0.54
2.6
1.5
0.4
How long do your colds normally last?
Fewer than 3 days
Up to 5 days
More than 5 days
4
45
51
6
45
49
When you catch a cold, do you normally
expect to get (%)
Headaches
Sore throat
Blocked sinuses
A chest infection
59
94
76
31
66
91
70
45
67
33
66
34
Do the secondary effects of colds keep you out
of action, away from college, or off work? (%)
No
Yes
If yes, for approximately how many days
(average) after each infection?
Do you suffer from asthma or any chronic
obstructive airways disease that makes it more
serious if you catch a cold? (%)
No
Yes
4.4
100
0
5
98
2
Continued
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Pretrial Questionnaire (cont’d)
Question
Have you ever taken a vitamin C supplement
to prevent winter infections? (%)
No
Yes
If yes, have you ever had problems with
heartburn, acid indigestion, or other gastric
upsets? (%)
No
Yes
Active
Treatment
Placebo
42
58
54
46
84
16
79
21
End-of-Survey Questionnaire
Question
Active
Treatment
Placebo
Have you taken your tablets every day
for the past 60 days? (%)
Yes
Almost
No
82
18
0
56
43
2
While taking the tablets, did you suffer
any problems with (%)
Heartburn
Indigestion
Stomach upset
8
4
0
4
11
0
During the past 60 days, how many episodes
of coughs, colds, or flu have you had?
Coughs
Colds
0.28
0.6
During the past 60 days, have you caught
any other infection? (%)
No
Yes
90
10
0.3
0.6
83
17
Continued
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Preventing the Common Cold
End-of-Survey Questionnaire (cont’d)
Active
Treatment
Placebo
How have you felt during the past 60 days
compared with previous winters? (%)
Much better
Better
The same
Worse
15
49
36
0
21
33
46
0
Based on your experience in the past 60 days,
would you continue taking a supplement
for the rest of the winter? (%)
Yes
No
85
15
70
30
Based on your experience, would you
recommend a winter course of a vitamin C
supplement to your friends and family? (%)
Yes
No
81
19
70
30
Question
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Volume 19 No. 3, May/June 2002
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