Clinical Briefs: Proud to Be an American (Ginseng)
With Comments from Russell H. Greenfield, MD. Dr. Greenfield is Medical Director, Carolinas Integrative Health, Carolinas HealthCare System, Charlotte, NC, and Clinical Assistant Professor, School of Medicine, University of North Carolina, Chapel Hill, NC.
Source: Predy GN, et al. 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;173:1043-1048.
Goal: To assess the efficacy of an extract of North American ginseng (Panax quinquefolium) root for prevention of upper respiratory tract infections (URIs).
Design: Randomized, double-blind, placebo-controlled study performed over four months of a cold and flu season in Canada.
Subjects: Participants were aged 18-65 years with a history of at least two colds during the previous year (n = 323, data available for analysis on 279 subjects).
Methods: Subjects were recruited through local media advertisements and then screened by phone. Subjects then completed a questionnaire about their history of prior colds and were provided a two-month supply of either North American (NA) ginseng extract (200 mg/capsule) or placebo (rice powder) with instructions to take two capsules each morning after breakfast. Contact was made with participants by e-mail or telephone to help ensure compliance with the study protocol. Subjects were to complete a daily log each evening, were advised to contact study investigators at the first sign of a cold, and were asked to record the severity of cold-related symptoms (fever, runny nose, sneezing, etc.) as well as perceived side effects.
Participants returned for evaluation two months into the study, at which time they received additional capsules, and again at study's end at four months. The primary endpoint of interest was the number of reported and verified colds per subject. Secondary endpoints included symptom severity, number of days of illness, and duration of all colds during the four-month period.
Results: The mean number of verified colds per person was less in the ginseng group (P = 0.017). A significant benefit was associated with ginseng use when considering cold recurrence, with only 10% in the ginseng group reporting more than one cold compared with 22.8% in the placebo group (P = 0.004). Symptom scores and total number of days with cold symptoms were likewise significantly less in the ginseng group.
Conclusions: The specific extract of NA ginseng studied significantly reduced the mean number of colds per person and the risk of recurrent cold during four months of a cold and flu season.
Study strengths: Degree of follow-up; integrity of randomization; standardization of extract; high degree of compliance; intention-to-treat analysis.
Study weaknesses: Compliance determined by weighing returned bottles; imbalanced treatment assignment; study did not distinguish between common colds and the flu.
Of note: More than 1 billion colds/year are reported in the United States alone; a published trial of NA ginseng in institutionalized elderly subjects showed a marked benefit in preventing illness due to influenza and respiratory syncytial virus; potential subjects were barred from participation if they had received the flu vaccine within six months of the study; blinding appears to have been well-maintained during the trial; two subjects in the ginseng group were withdrawn from the study after being diagnosed with Type 2 diabetes; extracts of NA ginseng appear to have a broad range of activity against a variety of viral strains; other herbs commonly referred to as ginseng include Asian ginseng (Panax ginseng) and Siberian ginseng (Eleutherococcus senticosus), though the latter is a not a true ginseng.
We knew that: The average American gets 2-6 colds per year; antihistamines and decongestants have limited efficacy, while some antiviral drugs are associated with the potential for significant side effects; extracts of Panax quinquefolium have been found to possess a wide variety of immunomodulatory effects; one study raised the specter that certain antiviral drugs may induce specific viral resistance.
Clinical import: Every winter patients flock to doctor's offices, urgent care centers, and emergency departments in search of relief from viral URIs. The majority of available pharmaceutical agents offer little in the way of protection against such infection, let alone treatment of symptoms, and herbal remedies long held dear for the same indications have not consistently held up under intense scrutiny. This well-done study brings to light the potential of NA ginseng as prophylaxis against viral URIs, and with impressive results. Yes, further study is warranted, but the extract of NA ginseng appears to be both safe and effective for adults, and there simply are no effective conventional interventions protecting against the common cold. May it prove as effective in kids ¼ .
What to do with this article: Keep a hard copy in your file cabinet. [Thanks to Kathi Kemper, MD, MPH, for bringing this paper to our attention.]
Greenfield RH. Proud to be and American (ginseng). Altern Med Alert 2005;8(12):144.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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