C.Health
Wed, Nov-02-05, 17:16
http://www.cmaj.ca/cgi/content/full/173/9/1043
Background: Upper respiratory tract infections are a major
source of morbidity throughout the world. Extracts of the
root of North American ginseng (Panax quinquefolium) have
been found to have the potential to modulate both natural
and acquired immune responses. We sought to examine the
efficacy of an extract of North American ginseng root in
preventing colds.
Methods: We conducted a randomized, double-blind,
placebo-controlled study at the onset of the influenza season.
A total of 323 subjects 18-65 years of age with a history of
at least 2 colds in the previous year were recruited from the
general population in Edmonton, Alberta. The participants were
instructed to take 2 capsules per day of either the North
American ginseng extract or a placebo for a period of 4
months. The primary outcome measure was the number of
Jackson-verified colds. Secondary variables measured included
symptom severity, total number of days of symptoms and
duration of all colds. Cold symptoms were scored by subjects
using a 4-point scale.
Results: Subjects who did not start treatment were excluded
from the analysis (23 in the ginseng group and 21 in the
placebo group), leaving 130 in the ginseng group and 149 in
the placebo group. The mean number of colds per person was
lower in the ginseng group than in the placebo group (0.68
[standard deviation (SD) 0.82] v. 0.93 [SD 0.91], difference
0.25%, 95% confidence interval [CI] 0.04-0.45). The
proportion of subjects with 2 or more Jackson-verified colds
during the 4-month period (10.0% v. 22.8%, 12.8% difference,
95% CI 4.3-21.3) was significantly lower in the ginseng group
than in the placebo group, as were the total symptom score
(77.5 [SD 84.6]
v. 112.3 [SD 102.5], difference 1.5%, 95% CI 1.2-2.0) and the
total number of days cold symptoms were reported (10.8 [SD
9.7] v. 16.5 [SD 13.8] days, difference 1.6%, 95% CI
1.3-2.0) for all colds.
Interpretation: Ingestion of a
poly-furanosyl-pyranosyl-saccharide-rich extract of the roots
of North American ginseng in a moderate dose over 4 months
reduced the mean number of colds per person, the proportion of
subjects who experienced 2 or more colds, the severity of
symptoms and the number of days cold symptoms were reported.
Background: Upper respiratory tract infections are a major
source of morbidity throughout the world. Extracts of the
root of North American ginseng (Panax quinquefolium) have
been found to have the potential to modulate both natural
and acquired immune responses. We sought to examine the
efficacy of an extract of North American ginseng root in
preventing colds.
Methods: We conducted a randomized, double-blind,
placebo-controlled study at the onset of the influenza season.
A total of 323 subjects 18-65 years of age with a history of
at least 2 colds in the previous year were recruited from the
general population in Edmonton, Alberta. The participants were
instructed to take 2 capsules per day of either the North
American ginseng extract or a placebo for a period of 4
months. The primary outcome measure was the number of
Jackson-verified colds. Secondary variables measured included
symptom severity, total number of days of symptoms and
duration of all colds. Cold symptoms were scored by subjects
using a 4-point scale.
Results: Subjects who did not start treatment were excluded
from the analysis (23 in the ginseng group and 21 in the
placebo group), leaving 130 in the ginseng group and 149 in
the placebo group. The mean number of colds per person was
lower in the ginseng group than in the placebo group (0.68
[standard deviation (SD) 0.82] v. 0.93 [SD 0.91], difference
0.25%, 95% confidence interval [CI] 0.04-0.45). The
proportion of subjects with 2 or more Jackson-verified colds
during the 4-month period (10.0% v. 22.8%, 12.8% difference,
95% CI 4.3-21.3) was significantly lower in the ginseng group
than in the placebo group, as were the total symptom score
(77.5 [SD 84.6]
v. 112.3 [SD 102.5], difference 1.5%, 95% CI 1.2-2.0) and the
total number of days cold symptoms were reported (10.8 [SD
9.7] v. 16.5 [SD 13.8] days, difference 1.6%, 95% CI
1.3-2.0) for all colds.
Interpretation: Ingestion of a
poly-furanosyl-pyranosyl-saccharide-rich extract of the roots
of North American ginseng in a moderate dose over 4 months
reduced the mean number of colds per person, the proportion of
subjects who experienced 2 or more colds, the severity of
symptoms and the number of days cold symptoms were reported.