Ineffectiveness of Echinacea for Prevention of Experimental Rhinovirus Colds

Abstract

The purpose of this study was to assess the effectiveness of echinacea for the prevention of experimental rhinovirus colds. Infection occurred in 44 and 57% and illness occurred in 36 and 43% of the echinacea-and placebo-treated subjects, respectively. This preparation of echinacea had no significant effect on either the occurrence of infection or the severity of illness.Since the Dietary Supplement Health and Education Act was enacted by Congress in 1994 to modify the Food and Drug Administration regulation of dietary supplements, there has been a dramatic increase in the marketing and sale of these products. Echinacea is one of the most popular herbal remedies and is reported to have immunomodulatory activity that is beneficial for the treatment of common cold symptoms. Clinical studies on the effect of echinacea on the common cold have used a variety of different echinacea preparations and study designs (8,13,16). Different preparations of echinacea differ in chemical composition due variation in the plant species or the part of the plant that is used as the starting material or because of differences in the manufacturing process or dosage form (1, 3). The purpose of this study was to use the experimental cold model to evaluate the effectiveness of an echinacea preparation with a defined chemical profile for the prevention of rhinovirus colds.Subjects Ն18 years of age were recruited for these studies from the university community of the Medical University of South Carolina. Volunteers with a serum titer of neutralizing antibody to the study virus of Յ1:4 were treated with echinacea (300 mg) or a placebo three times each day for 14 days prior to virus challenge. All volunteers were challenged with 100 to 300 50% tissue culture-infective doses of rhinovirus type 23, and then the treatment was continued for 5 days after the virus challenge. Virus infection was documented by virus cultures and antibody responses, and illness severity was assessed by a modification of a previously published method (12,14). The echinacea preparation used in this study was analyzed by reversed-phase high-pressure liquid chromatography by Rudolf Bauer (Institut für Pharmazeutische Biologie, Düsseldorf, Germany) using published methods (2-6) and found to contain 0.16% cichoric acid with almost no echinacosides or alkamides. Written informed consent was obtained prior to study participation, and subjects were compensated for participation.One hundred seventeen subjects were enrolled in the trial and treated with either echinacea (63 subjects) or a placebo (54 subjects) for 2 weeks. Sixteen subjects (eight active, eight placebo) had a respiratory illness on day 0 and were not challenged with rhinovirus, four subjects in each group withdrew from the study prior to challenge, and one subject treated with echinacea was removed from the study due to an adverse event. The remaining 92 subjects were challenged with rhinovirus type 23 and continued on study medication as outpatients for an additional 5 days. On day 0 prior to virus challenge, ...

Echinaceaspecies (Echinacea angustifolia(DC.) Hell.,Echinacea pallida(Nutt.) Nutt.,Echinacea purpurea(L.) Moench): a review of their chemistry, pharmacology and clinical properties

“…In one study, adult volunteers (n ¼ 117 enrolled) with a serum titre of neutralizing antibody to rhinovirus of 1:4 received echinacea (300 mg) or placebo three times daily for 14 days before and for 5 days after challenge with rhinovirus (n ¼ 92 challenged due to study withdrawals). It is not stated in a report of the study (Turner et al 2000) whether random allocation to study group was undertaken or whether participants were masked (blind) to treatment allocation, although a blinding check before virus challenge found that 30 (60%) of the 50 echinacea recipients and 19 (45%) of the 42 placebo recipients thought they were receiving the ''active'' treatment (P ¼ 0.21).…”

“…Several new trials of echinacea preparations in the prevention of the common cold have been completed since the Cochrane review, but most have not shown beneficial effects for echinacea preparations compared with placebo on main outcome measures (Melchart et al 1998;Grimm & Mu¨ller 1999;Turner et al 2000;Cohen et al 2004;Sperber et al 2004).…”

“…Two further studies have tested the effects of echinacea preparations for the prevention of colds due to experimental rhinovirus infection (Turner et al 2000;Sperber et al 2004). In one study, adult volunteers (n ¼ 117 enrolled) with a serum titre of neutralizing antibody to rhinovirus of 1:4 received echinacea (300 mg) or placebo three times daily for 14 days before and for 5 days after challenge with rhinovirus (n ¼ 92 challenged due to study withdrawals).…”

Enhancement of broiler performance and immune response by Echinacea purpurea supplemented in diet

“…However, results on the in vivo efficacy of Echinacea products have been controversial. While, Rehman et al (1999) showed an increase in primary and secondary immunoglobin G response in rats treated with E. purpurea, animal and human studies have shown that E. purpurea had generally little or no effect on existing serum immunoglobin levels or on specific antibody production (Melchart et al, 1998;Grimm and Müller, 1999;Turner et al, 2000).…”

Clinical Practice Guideline: Management of Sinusitis

“…A recently published study provides evidence that zinc nasal gel is effective in shortening the duration of symptoms of the common cold when taken within 24 hours of their onset. 73 Studies performed among adults indicating efficacy of Echinacea preparations in stimulating the immune system, thereby reducing the incidence, duration, or severity of respiratory infections, are debated 74,75 ; however, a recent metaanalysis suggested a predominance of generally positive effects. 76 Physicians treating children and young adults should be aware that many of their patients are using complementary therapies, often without informing them.…”