Reviewed: Predy GN, Goel V, Lovlin R, Donner A, Stitt L, Basu TK. Efficacy of an extract of North American ginseng containing poly-furanosyl-pyranosyl-saccharides for preventing upper respiratory tract infections: a randomized controlled trial. CMAJ. 2005;173(9):1043-1048.
On average, Americans get 2-6 colds each year. Finding ways to reduce the frequency of the common cold is important. Botanicals that stimulate the immune system have been used to combat the common cold, but clinical studies have sometimes been inconclusive.
Preparations made from the roots of American ginseng (Panax quinquefolius L., Araliaceae) have demonstrated immuno- modulatory effects; however, only recently has there been clinical research conducted on this traditional herb—most of it being in the area of controlling blood sugar levels in type 2 diabetics.
Most scientific literature on both Asian ginseng (Panax ginseng C.A. Meyer) and American ginseng tends to focus on the ginsenosides as the putatively primary active compounds.A patented poly-furanosyl-pyranosyl-saccharides-rich extract of American ginseng roots (COLD-fX®, also known as CVT–E002, produced by CV Technologies Inc, Edmonton, Alberta, Canada) has been shown in vitro to demonstrate immunostimulating effects. An increase in immune activity may decrease susceptibility to colds. The purpose of this clinical trial was to test this extract as a prophylactic treatment for upper respiratory tract infections.
Healthy subjects (n = 323) who had experienced at least 2 colds in the past year participated in this randomized, double-blind, placebo-controlled study conducted at the University of Alberta, Edmonton, Canada. For 4 months the subjects took either placebo or 400 mg per day of the CVT-E002 patented standardized extract (concentrated to 80% poly-furanosyl-pyranosyl-saccharides and 10% protein).
Treatment began just after the onset of influenza season. Subjects were instructed not to take any other cold medication unless advised by their physician. Every evening the subjects completed a diary detailing the severity of cold-related symptoms. A 2-day total symptom score greater than 14 was considered to indicate a modified Jackson-criteria-verified cold. The Jackson score is one of the most accurate and restrictive definitions of a cold because it quantifies cold symptoms. By contrast, other studies often use the less precise method of simply noting the absence or presence of a runny nose to define a cold.
There were no significant differences in baseline characteristics between the groups. Compliance was rated high in both groups and blinding was maintained. (Seventy-seven percent of the patients taking placebo thought they were taking COLD-fX, indicating that the formulation and administration of the placebo was successful. In some clinical trials with other herbs, the preparation of placebo and lack of successful blinding has sometimes been inadequate, thereby producing equivocal results.)
Overall, there was a 13% reduction in the absolute risk of getting recurrent colds meeting the Jackson criteria. The mean number of Jackson-verified colds per person was significantly less in the COLD-fX group than in the placebo group (P < 0.017). Fewer subjects in the COLD-fX group than in the placebo group reported contracting at least 1 cold during the study, but the difference was not statistically significant. However, there was a significant difference in the recurrence of colds, with 10% in the COLD-fX group having more than one cold compared with 23% in the placebo group (P = 0.004), representing a 56% relative risk reduction. COLD-fX-treated subjects had less severe symptoms (P = 0.002) and were sick for fewer days (P < 0.001). Both COLD-fX and placebo were well tolerated with few adverse effects. There was no significant difference between the 2 groups with respect to the use of NSAIDs (non-steroidal anti-inflammatory drugs) or antibiotics.
The authors concluded that COLD-fX is a safe and effective treatment for reducing the absolute risk of recurrent colds and the mean number of colds per person. They do point out that the findings apply only to healthy adults and further studies in children and immuno-compromised adults are needed. This study had excellent methodology and reporting, which provides additional credibility to the findings. While a 13 bsolute reduction in the risk of getting a recurrent cold does not seem particularly clinically impressive, more promisingly, the authors report that “the total symptom score was 31.0% lower and the total number of days symptoms were reported [was] 34.5% less in the ginseng group than in the placebo group over the 4-month intervention period.”
Also, the activity of COLD-fX seems to compare favorably with that of common antiviral drugs such as rimantadine, amantadine, zanamivir, and oseltamivir (Tamiflu®). COLD-fX was reported in an earlier study with elderly people to reduce the relative risk of laboratory-confirmed influenza infections by 89%.1 This is a level of effectiveness similar to that of zanamivir and oseltamivir.2 These antiviral agents have been reported to reduce the severity and duration of illness by 1.5-2.5 days,3 while COLD-fX treatment reduced the duration of a cold by 2.4 days.
The authors of this study further assert that, “This North American ginseng extract has a broader range of activity (than common antivirals) and hence is potentially more effective in combating different strains of virus.” Due to the unique chemical profile of the CVT-E002 (COLD-fX) preparation, it is highly doubtful whether the results of the clinical research on this patented preparation could be applicable to research conducted with conventional extracts of American ginseng roots.
—Heather S. Oliff, PhD, and Mark Blumenthal
1. McElhaney JE, Gravenstein S, Cole S, Davidson E, O’Neill D, Petigean S et al. A placebo-controlled trial of a proprietary extract of North American ginseng (CVT – E 002) to prevent acute respiratory illness in institutionalized older adults. J Am Geriatr Soc. 2004; 52:13-19.
2. Turner D, Wailoo A, Nicholson K, Cooper N, Sutton A, Abrams K. Systematic review and economic decision modeling for the prevention and treatment of influenza A and B. Health Technol Assess. 2003; 7:1-170.
3. Stiver G. The treatment of influenza with antiviral drugs. Can Med Assoc J. 2003; 168(1):49-57.