References the incidence, duration, or severity of colds compared to a placebo. There is also conjecture, but no formal research findings, that Echinacea reduces the strength of the immune system response when used continuously over time (Jurcic et al., 1989).
Recent research has to a great extent concentrated on early Echinacea intervention for relieving the symptoms and duration of colds and flu-like infections. For example, Bräunig et al. (1992) demonstrated a statistically significant improvement of symptoms over placebo with early intervention, that is, when symptoms first appear. Hoheisel et al. (1997) in a randomized, double-blind, single-center placebo-controlled study demonstrated that the use of an expressed juice of E. purpurea, given orally from the onset of the initial symptoms of an upper respiratory infection or cold, inhibits the full expression of the infection and, moreover, shortens the recovery time. Melchart et al. (1994) conducted a meta-analysis of 26 controlled clinical trials (18 randomized, 11 double blind) on the immunomodulatory effects of Echinacea; 16 of the 18 randomized trials claimed positive results, suggesting that preparations containing extracts of Echinacea can be clinically effective immunomodulators. Melchart et al. (1998) subsequently reviewed 16 trials and found that some Echinacea compounds may have stronger effects than a placebo. Most of the research studies showed positive results but without enough evidence to support any specific Echinacea product. Another issue has been that of the efficacy of tablet vs. liquid extract. Quite a few articles and research studies have reviewed the digestibility and absorption of the tablet forms of Echinacea. The majority of researchers agree that the liquid forms, either in a tea or an alcohol base, are best for maximum absorption and thus maximum efficacy (Wichtl and Bisset, 1994; British Herbal Medicine Association, 1996).
In a research study, Lindenmuth and Lindenmuth (2000) tested the efficacy of an Echinaceacompound herbal tea compound on duration and severity of symptoms of cold and flu — specifically, scratchy throat, runny nose, and fever — using a randomized double-blind study. Subjects of the study were employees of Rest Haven-York Nursing and Rehabilitation Center, a 167-bed facility in York, PA. Employees were eligible for the study if they reported the earliest symptoms of cold or flu: runny nose, scratchy throat, or fever. Persons excluded from the study were pregnant women, nursing mothers, those with known allergies to coneflowers, those who stated that they were allergic to any flowering plants or pollens, and those with acute infections and already taking antibiotics.
In December 1998, employees of the nursing and rehabilitation center were advised of the study and received information sheets about Echinacea. They were informed that from 1 January 1999 through 30 March 1999, at the earliest sign of a cold or flu symptoms (runny nose, scratchy throat, fever) they could on a voluntary basis be participants in an experimental research study for the purpose of testing the effectiveness of Echinacea. Those persons with symptoms who volunteered to be in the study were then randomly assigned throughout the time period to either the experimental group (Echinacea) or control group (placebo). The assignment was conducted by specially trained secretarial personnel not associated with the study who had no knowledge of which of two boxes contained packets of Echinacea Plus or Eaters Digest (placebo) tea bags. Upon reporting to the secretarial personnel, each subject received a packet containing 21 tea bags of like appearance (wrappings) of either Echinacea Plus or the placebo. Subjects were assigned numbers, as were the boxes of tea bag packets.
The herbal dietary supplement, Echinacea Plus, was prepared and packaged by Traditional Medicinals®, Inc. of Sebastopol, CA. Echinacea Plus contains a proprietary blend of the leaves, flowers, and stems of organically grown E. purpurea and E. angustifolia, plus a water soluble dry extract of E. purpurea root (6:1). In combination, this delivers the equivalent of 1.275 mg of dried herb and root per tea bag serving. When prepared according to label directions, a minimum of 31.5 mg of total phenolic compounds (calculated as caftaric acid, cichoric acid, chlorogenic acid, and echinacoside) are yielded into one dose of brewed tea, as determined by high-performance liquid chromatography (HPLC). The herbal mixture additionally contains small amounts of two adjuvant components, lemongrass leaf (Cymbopogon citratus [DC. ex Nees] Stapf.) and spearmint leaf
(Mentha spicata L.). At higher dosages these components might have an effect; however, both lemongrass leaf and spearmint leaf occur in the formula as "flavor corrigents," which are allowed in an herbal tea formula at up to 20% of the formula. This makes the tea palatable in order to ensure patient compliance and tolerance; mint leaf is a widely used flavor corrective in medicinal herbal preparations. (Schilcher, 1997; Weiss, 1988). Specific instructions for boiling, steeping, and dosage were given to each subject as follows: Pour 8 oz. of boiling water over one tea bag and steep, covered, for 10 to 15 minutes. Drink 5 to 6 cups on the first day of symptoms, titrating to 1 cup by the 5 th day (Lindenmuth and Lindenmuth, 2000).
The placebo for the control group, "Eater's Digest" herbal tea from Traditional Medicinals, was chosen because the product promotes healthy digestion and has no history of having any effect on cold or flu symptoms. The cinnamon, ginger, and peppermint inclusions could possibly have an effect if given in a higher dosage; in the indicated amounts, they serve as flavor correctives (Schilcher, 1997; Weiss, 1998). Moreover, this tea contains no stimulants and has no obvious or easily recognizable aroma or flavor characteristics that would cause it to be easily discernible from the Echinacea Plus tea by a person with an untrained palate. Subjects would not be likely to have the capability to determine the taste of the Echinacea compound, especially since the tea is a multiherb formula containing mint leaf. Furthermore, both the treatment group and control group teas in this study contained mint leaf. A natural flavor could have been added to both teas in an attempt to mask any recognizable or known characteristic flavors, but the problems with that approach are twofold. Subjects may have needed to believe that they were drinking medicinal herbal tea; a flavored tea might have had an influence on the results due to generally not being perceived as medicinal. Second, by adding an ingredient to the existing formula, the drug being studied is no longer the same as the drug in commerce (Echinacea Plus). Additionally, each tea bag (treatment and control) was specially wrapped in the same lining and paper to prevent olfactory and visual differentiation by subjects.
The control tea contained peppermint leaf (Mentha x piperita Linne); sweet fennel seed (Foeniculum vulgare Miller ssp. vulgare, var. dulce [Miller] Thellung); ginger rhizome (Zingiber officinale Roscoe); rose hip (Rosa canina L.); papaya leaf (Caricapapaya L.); alfalfa leaf (Medicago sativa L.); and cinnamon bark (Cinnamomum cassia J. Presl.) (Lindenmuth and Lindenmuth, 2000). Directions for preparation given subjects in the control and treatment groups were the same.
Bräunig and Knick (1993) reported a study in which a daily dosage of 90 drops of a hydroal-coholic tincture (1:5) (equal to 900 mg of dried Echinacea root) is effective in reducing cold-type symptoms in comparison to a daily dosage of 450 mg of dried Echinacea root in a second group. Traditional Medicinals recommends 3 to 5 cups per day of the Echinacea formula, containing 1000+ mg of Echinacea per cup of tea (one bag). The protocol for this study (Lindenmuth and Lindenmuth, 2000) was established at 5 to 6 cups of the tea on the first day of symptoms, titrating to 1 per day for the last of the 5 days. The control (placebo) group was placed on the same schedule.
A questionnaire was designed in a brief format in order to encourage subjects to not only complete it but also to do so with accuracy. It was administered to each subject 14 days after having started the program. Question 1 addressed the effectiveness of the tea in relieving cold or flu symptoms; question 2 requested the number of days that cold and flu symptoms lasted; question 3 asked for the time it took for the subjects to notice any difference in their symptoms. (See Table 18.1 for questionnaire and Table 18.2 for scoring code.) Our hypotheses anticipated a significant difference in effectiveness of relieving cold or flu symptoms between the experimental group (Echinacea) and control group (placebo), a significant difference between the experimental group (Echinacea) and control group (placebo) in the number of days the symptoms lasted, and a significant difference between the experimental group (Echinacea) and control group (placebo) in the number of days it took for subjects to notice a change. Means, standard deviations (SDs), and t-tests were run for each question. Confidence intervals of 95% were utilized with statistical significance set at p < 0.05 level (two-tailed).
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