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By Yousry Naguib, Ph.D.
Vitamin Retailer, June 2001

Echinacea is a perennial herb native to North America. There are three main species of Echinacea that have been used commercially: Echinacea purpurea, Echinacea angustifolia, and Echinacea pallida. All are known as purple coneflower. In the United States, echinacea is often sold in a combination with goldenseal (Hydrastis canadensis) as a cold remedy. The potency of echinacea preparations can be tested by their tingling sensation on the tongue.
The chemical composition varies slightly for each echinacea species in the amount of active components. The roots have a different composition than their above-ground parts. The latter contain the active components: ferulic and caffeic acid derivatives (such as cichoric acid and echinacosides), and polysaccharides (such as arabinogalactan, rhamno-arabinogalactan). All parts of the plant, including roots and leaves, have been used in dietary supplement preparations.
The German Kommission E has approved the oral use of the aboveground parts of Echinacea purpurea for colds, respiratory tract infections, and its topical use for healing wounds. The Echinacea pallida root (fresh or dried) has also been approved for use in the treatment of cold infections.

Animal and Test-Tube Studies
The prophylactic role of echinacea was demonstrated in an animal study. Mice were fed a diet containing powder extract of Echinacea purpurea root (a product of PhytoAdrien, Quebec) 0.45mg/day, for one or two weeks. Control mice were fed the same diet without the echinacea extract. After treatment, mice were killed and assayed for natural killer (NK) cells and monocytes, (both are mediators of non-specific immunity and are first line of defense against virus-containing Cells).
There was a significant increase in NK cells & monocytes in the bone marrow and spleen one week following echinacea consumption. These results indicate that one mechanism of action of this herb is to stimulate new cell production [1].
Researchers at the University of California, San Diego, conducted another animal study on rats using Echinacea angustifolia. They proposed that echinacea might enhance the immune system by increasing antigen-specific immunoglobulin production.
The immune stimulatory ability of fresh-pressed juice of Echinacea purpurea was demonstrated in a test-tube study. Incubation of human peripheral blood macrophages with echinacea extract stimulated the production of cytokines, interleukins IL-1, IL-6, IL10, and tumor necrosis factor-alpha. Cytokines are proteins produced by the immune system to regulate cellular processes. These cytokines mediate the production of antibodies to fight bacteria and viruses [3a].
The active components alkamides isolated from Echinacea angustifolia have been shown in a test-tube experiment to inhibit the activity of the enzymes cyclooxygenase and lipoxygenase, suggesting an anti-inflammatory effect [3b].In another test-tube experiment, the active components Echinacosides and caffeoyl conjugates were found to protect collagen from free radical-induced degradation, suggesting the potential use of echinacea extracts in the prevention of skin photo-damage [3c].

Human Clinical Trials
Echinacea purpurea is the most investigated of the species. Several constituents are believed to be immunologically active, including polysaccharides, caffeic acid derivatives (cichoric acid) and alkamides. The therapeutic efficacy of Echinacea in the treatment of colds and upper respiratory infections has been demonstrated in a number of placebo-controlled trials.
One trial examined the efficacy of two different doses (450mg/day and 900mg/day) of expressed juice of Echinacea purpurea roots in 180 patients with colds and upper respiratory infections. Both echinacea and placebo juice contained 50 percent alcohol. The study found that the higher dose of Echinacea purpurea root extract significantly improved the cold symptoms, whereas the lower dose of echinacea was not superior to placebo juice [4].
The same researchers performed another placebo-controlled trial on 160 patients with colds and upper respiratory infections using an ethanolic extract of Echinacea pallida roots (900mg/day). All patients were treated and followed for eight to 10 days. Treatment with Echinacea pallida extract reduced the average length of infection from 13 days to 9.8 days in a bacterial infection and to 9.1 days in a viral infection. The study concluded that treatment with E pallida shortens the course of an upper respiratory tract infection [5].
In a recent double-blind trial, 108 patients with a history of more than three colds or respiratory infections in the preceding year were randomly assigned to either 4ml extract of E. purpurea or 4ml placebo-juice twice a day. After eight weeks of treatment, 65 percent of the echinacea group and 74 percent of the placebo group had at least one cold or respiratory infection. Median duration of colds and respiratory infections was 4.5 days in the echinacea group and 6.5 days in the placebo group. The study concluded that treatment with Echinacea purpurea extract did not significantly decrease the incidence, duration or severity of colds and respiratory infections compared to placebo [6].
In a placebo-controlled double-blind clinical trial carried out in Sweden, 246 subjects who caught a cold were instructed to take, three times daily, two tablets of either Echinaforce (at two doses of 6.78mg/tablet or 48.27mg/tablet of the extract of freshly harvested Echinacea purpurea, or a crude extract (29.6mg/tablet) of Echinacea purpurea root only, or placebo until they felt healthy — but not for longer than seven days. All treatments were well tolerated.
There was significant improvement in cold-symptoms for subjects taking Echinaforce at either dosage level than those taking crude root extract or placebo. Symptoms included runny nose, sneezing, watering or burning eyes, sore throat and difficulty swallowing, headache, fever, cough, earache and other cold-related symptoms. There was no significant difference in symptom reduction between crude root extract and placebo, or between the two Echinaforce dosages. The study concluded that Echinaforce administered as two tablets, three times a day at either 6.78mg/tablet and 48.27mg/tablet is superior to placebo and crude root preparation in the treatment of colds [7].
A recent randomized, double-blind, placebo -controlled study, carried out in the USA, on 95 subjects with early symptoms of cold (runny nose, scratchy throat, fever) showed that treatment with Echinacea Plus tea (five to six cups per day) at early onset of cold symptoms was effective for relieving these symptoms in a shorter time than placebo [8].

German Studies
In a German multi-center, randomized, double-blind, placebo-controlled study, 263 patients were given three tablets of either a standardized combination herbal remedy Esberitox N or placebo for seven to nine days. The herbal remedy group showed a significant improvement as compared to the placebo group. The efficacy of the herbal remedy was most prominent in patients who started treatment at all early phase of their cold. No adverse events were reported [9]
A German meta-analysis of 16 trials (eight preventive trials, and eight trials on treatment of upper respiratory tract infections) with 3,396 participants suggests that some Echinacea preparations may be better than placebo. The majority of the studies reported positive results. The study, however, concluded that there is not enough evidence to recommend a specific echinacea product treatment or prevention of common colds [10].
Another German study which examined immunomodulatory activity of different preparations of Echinacea found that only intravenous treatment with Echinacea angustifolia and oral treatment with an alcoholic extract of Echinacea purpurea roots, for five consecutive days, significantly enhanced phagocytosis (ingestion of microbes and foreign bodies by immune cells), compared to a placebo [12].
Echinacea has also been shown to counteract the immunosuppressant effects of exercise in athletes. While moderate exercise has a beneficial effect, exhaustive exercise has been reported to suppress natural killer cell activity, reduce cytokines secretion, and increase interleukin-6 (11-6) and soluble interleukin-2receptor (sIL-2R) in blood and urine. The release of IL-6 is characteristic for the acute phase response to infection or injury.
The ability of echinacea to counteract the immunosuppressive effects of heavy exercise has been evaluated in a randomized, placebo-controlled trial involving 42 male athletes undergoing regular training. The men were given either echinacea (8ml of a standardized extract of the pressed juice of Echinacea purpurea, marketed as Echinacin), magnesium or placebo for four weeks. In comparison to the placebo group, Echinacin markedly reduced sIL2R release, and facilitated IL-6 release in response to strenuous exercise.
None of the subjects in the echinacea group developed an upper respiratory infection, while 25 percent of the subjects in the magnesium and placebo groups developed infections.
'The study concluded that prophylactic treatment of athletes with Echinacin counteracts the immunosuppressant effects of exhaustive exercise and reduces the risk of upper respiratory infections [13].

Because of the immunostimulant property of echinacea, it should not be given with immunosuppressants such as corticosteroids and cyclosporine.
A Canadian prospective study involving 206 women who used echinacea products during pregnancy found no association between gestational use of echinacea and increased risk for major malformations, including chromosomal abnormality [14].
The consensus of research studies is that echinacea is indeed effective in reducing the duration and severity of cold symptoms. It is recommended to take Echinacea at the onset of cold symptoms for about two weeks. Echinacea is not to be used continuously.

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[14] Gallo M et al. Arch Intern Med 2000; 160:3141