The herb Echinacea has been the subject of a considerable amount of misinformation and misunderstanding concerning its active principles, mode of action, clinical efficacy and cautions and contraindications. One important reason behind such confusion is the many types of Echinacea products on the market. This has an historical background. The Native Americans, and the Eclectics physicians who adopted their use of Echinacea, preferred the root. In fact, the Eclectics only used a water-ethanol (lipophilic) extract of dried E. angustifolia root high in alkylamides. These particular phytochemicals impart a persistent tingling sensation in the mouth and stimulate the flow of saliva, a sign of good quality according to King’s American Dispensatory.[i] In Europe during the 1930’s, the German herbalist Madaus promoted E. purpurea as it was easier to grow. Being somewhat influenced by the homeopathic approach of using fresh plant tinctures, his firm eventually developed a hydrophilic product prepared from the stabilised juice of fresh E. purpurea tops (aerial parts). This is still the most popular form of Echinacea in Germany. Another popular European product is a fresh plant tincture of the whole plant of E. purpurea.
As might be expected, these different products exhibit substantial variations in their phytochemical content (and hence by definition their pharmacological and clinical properties). Yet they are typically discussed in popular writing, on websites and even in the scientific literature under the generic term “Echinacea”, as if they shared identical properties. Hence a very basic concept of phytotherapy, the overriding importance of the part of the plant being used, appears to have been overlooked or ignored. The way Echinacea is prepared also creates large differences. Specifically, the hydrophilic type of product will be low in alkylamides and higher in water-soluble compounds such as polysaccharides, whereas a lipophilic product will be much higher in alkylamides (especially if prepared from the root).
One of the key issues in the Echinacea literature is whether the herb treats or prevents respiratory infections. Research I have been involved in, either as a co-author or adviser, has provided us with an interesting perspective on this topic, as it applies to a combined lipophilic extract of E. angustifolia and E. purpurea roots.
There are actually relatively few clinical trials of Echinacea root in the treatment of acute respiratory infections and the results of such trials are mixed. Acute viral respiratory infections were certainly not the mainstay of the traditional use of Echinacea root by the Eclectic physicians. This common conception (or perhaps misconception) of the role of Echinacea has developed in modern times, probably as an extrapolation of its immune system reputation and driven by companies wishing to exploit a ready over-the-counter sale. Such a popular use of Echinacea also fitted in well with the ill-advised notion that the herb could only be taken for a few days at a time. In fact, the clinical trial evidence is considerably more supportive of the value of Andrographis in the treatment of colds and mild influenza (see my previous column on this herb).
However, to avoid any confusion, I need to point out here that I am not referring to studies on other plant parts of Echinacea (such as the flowering tops).
The studies I mentioned above are as follows. The first trial, of which I was a co-author, is relatively recent and received considerable media coverage in the US. In a well-designed trial involving 719 patients, a combination of E. purpurea and E. angustifolia roots standardised to 4.2 mg alkylamides/ tablet did not substantially alter the course of the common cold.[ii] Patients were assigned to 1 of 4 parallel groups: no tablets, placebo tablets (blinded), Echinacea tablets (blinded), or Echinacea tablets (unblinded, open-label). Echinacea groups received the equivalent of 10.2 g of dried Echinacea root during the first 24 hours and 5.1 g during each of the next 4 days. The primary outcome was the area under the curve for global severity, with severity assessed twice daily by self-report using the Wisconsin Upper Respiratory Symptom Survey (WURSS), short version.
Of the 719 patients enrolled, 713 completed the trial. Mean global severity was 236 and 258 for the blinded and unblinded Echinacea groups, respectively; 264 for the blinded placebo group; and 286 for the no-pill group. A comparison of the two blinded groups showed a 28-point trend toward benefit for Echinacea (p=0.089). Mean illness duration in the blinded and unblinded Echinacea groups was 6.34 and 6.76 days, respectively, compared with 6.87 days in the blinded placebo group and 7.03 days in the no-pill group. A comparison of the blinded groups showed a nonsignificant 0.53-day benefit (p=0.075) for Echinacea. In other words, taking a reasonably high dose of a lipophilic Echinacea root product after an infection started had only a modest impact, if at all, on the infection’s severity and duration. Even if a higher dose was used, the best outcome that could be expected might be a shortening of the infection by up to one day.
Far better not to get the infection at all! The ability of Echinacea root to prevent infections is supported by two clinical trials where I had an advisory role. The first is from some time ago.
In an unpublished study presented by the late Dr Anna Macintosh at the 1999 Convention of the American Association of Naturopathic Physicians, an Echinacea root formulation was compared against a herbal adaptogenic formulation and a placebo in the prevention of winter colds over a 90-day period.[iii] The trial recruited 260 medical students who were under stress from their studies. The placebo group averaged an infection rate of 10%, whereas this dropped to as low as 2% by day 70 (p=0.013) in the Echinacea group. The daily dose of Echinacea root was 1.7 or 3.5 g (two doses were consecutively trialled in the study).
The other trial has only recently been published. A randomised, double blind, placebo controlled clinical trial was undertaken with 175 participants travelling return from Australia to America, Europe or Africa for a period of 1 to 5 weeks on commercial flights via economy class.[iv] Participants were administered E. purpurea and E. angustifolia extract tablets (containing the equivalent of 1.275 g of root and standardised to 4.4 mg/tablet alkylamides) or placebo tablets, and trial dosing consisted of 3 protocols (priming, travel and sick), depending on the phase of travel of the participants and their health status. The priming dose was 2 tablets/day, the travel dose was 4 tablets/day and the dose when ill was 6 tablets/day.
Outcomes were assessed using questions about upper respiratory symptoms related to quality of life (based on WURSS-44). Each participant completed the survey before travel (baseline), less than 1 week after travel (return) and at 4 weeks after return from travel (follow-up). Compared with baseline, the average WURSS-44 scores for both groups increased immediately after travel (return) (p<0.0005). However, the placebo group had a significantly higher average WURSS-44 score (around double) compared with the Echinacea group (p=0.05). Hence, supplementation with Echinacea, if taken before and during travel, appeared to have a protective effect against the development of respiratory symptoms (and hence infection) during travel associated with long haul flights.
The results of these trials reverse the common understanding of Echinacea: that you take it for only short periods after getting an infection. In fact, the opposite is true. Echinacea root only has a modest benefit when taken after an infection, and its real value lies as a preventative. These trial results confirm my experience of 27 years in herbal practice and mean the real value in Echinacea root lies in its continuous use, at least during times when infection is more likely, such as stressful periods or during travel. (I have been taking Echinacea root almost continuously for 15 years and during that time have suffered only a handful of infections.)
There is no evidence to suggest that Echinacea root will wear out the immune system (that is, causes immune system tachyphylaxis). In a clinical study, the oral administration of E. purpurea root tincture over a 5-day period increased white blood cell activity compared with controls.[v] Only when the Echinacea was stopped did activity decline to normal (pre-test) values, demonstrating a typical washout effect. This German research has been widely mistranslated and misinterpreted as prolonged Echinacea use having a detrimental effect on immune function, which it clearly did not.
So have no fear about using Echinacea root long-term. You may even live longer. Mice certainly did. As touched on above, one of the persistent controversies about Echinacea is whether it is safe to be taken consistently for long periods. The answer, at least in mice, appears to be in the affirmative. Mice were fed E. purpurea root from 7 weeks of age to 13 months at typical human doses.[vi] Long-term use of Echinacea was in fact beneficial. By 13 months of age, 46% of the control mice fed the standard chow were still alive, compared with 74% of those consuming Echinacea. This effect on improving longevity is comparable to, or better than, most agents being touted as antiageing remedies.
References
[i] Felter HW, Lloyd JU: King’s American Dispensatory, 18 Edn, Vol 1, Eclectic Medical Publications, Portland, 1983, p 671-677.
[ii] Barrett B, Brown R Rakel D et al. Ann Intern Med 2010; 153(12): 769-777
[iii] McIntosh A, D’Huyretter K, Goldberg B et al: Infections prevention by herbal formulas in a high stress population, AANP Convention, Coeur d’ Arlene, 1999.
[iv] Tiralongo E, Lea R, Wee S et al. Planta Med 2010; 76(12): SL-49, 1190
[v] Jurcic K, Melchart D, Holzmann M et al. Z Phytother1989; 10:67-70
[vi] Brousseau M, Miller SC. Biogerontology 2005; 6: 157-163
by Kerry Bone
Professor Kerry Bone serves as the Director of Research and Development and is the co-founder and innovation driver at MediHerb. He was awarded the American Botanical Council’s (ABC’s) Varro E. Tyler Award for excellence in Phytomedicinal Research in 2016.
