Ingredient spotlight: Echinacea
Echinacea is among the most widely used herbs of the modern era, and among the most widely misunderstood. Every part of the plant has been put under scientific scrutiny, and expert opinion diverges sharply on which part to use, for how long, and in which patients.
Herbalists generally side with the plant's traditional uses — those adopted from Native American tribes by the Eclectic physicians of North America in the late nineteenth and early twentieth centuries. What follows looks at those traditional indications and at some of the scientific research supporting them, then turns to how echinacea is best used in light of both.
Traditional uses of echinacea
Native Americans preferred the root, working mainly with Echinacea angustifolia — though Echinacea purpurea root has a very similar chemical profile, and modern herbalists treat the two species as near-interchangeable.
Eclectic physicians prescribed it for snake bite, syphilis, typhus, septic wounds, diphtheria, tuberculosis and scarlet fever. That list supports the modern consensus that echinacea works chiefly on the innate immune response — the body's immediate reaction to a viral or bacterial threat.
Because it stimulates immunity, modern writers have suggested echinacea should be avoided in conditions marked by a hyperactive immune response, such as allergy or autoimmunity. There is in fact no evidence supporting that view,¹ and the Eclectics had no hesitation in using it for thyroid problems, diabetes, psoriasis and even cancer. In my own clinic I continue to use it successfully for allergies, chronic skin conditions and autoimmune thyroid disease.
How does it work?
The immune system is a magnificently complex orchestra of cells and chemical signalling, and it is difficult to establish exactly how any substance affects it — let alone something as chemically complex as a plant extract.
Still, the large body of in vitro (cell culture) and in vivo (animal) research supports several conclusions. Echinacea root stimulates phagocytosis — white blood cell activity — increases natural killer (NK) cells and monocytes, and modulates immunity through the body's cannabinoid system, acting mainly on CB2 receptors in immune tissue such as the spleen.² ³ ⁴ The active principles are thought to be the alkylamides, which are best captured in an ethanolic extract and are highly bioavailable.
Another common myth — that echinacea should not be taken long term — was dismantled by a Swiss research team in 2004. They showed that echinacea primes resting monocytes for a faster immune response by inducing messenger RNA for TNFα, an important inflammatory chemical. In monocytes that are already overstimulated, however, it first reduces and then extends the TNFα response.⁵ This matches herbalists' clinical experience: echinacea behaves as an immunomodulator in chronic inflammatory conditions, and is entirely safe for long-term use.
How to use echinacea
Dosage and timing are what matter with echinacea. For upper respiratory tract infections such as the common cold, the research points to using it preventatively, at 1–4.5g of dried root per day.
At that dose it has been shown to prevent winter colds in stressed-out medical students, and to reduce infection rates when taken before and during long-haul travel.⁶ ⁷
Treating an infection already established requires a far higher dose — up to 10–15g per day, which is how the Eclectics used it. Serious infectious disease, of course, also warrants proper medical attention.
In autoimmunity and other chronic inflammatory conditions, echinacea at a preventative dose may help reduce the presence of microorganisms provoking inappropriate immune responses through "molecular mimicry" — an established factor in the development of immune-related disorders. Treatment in these cases must be supervised by a clinical herbalist who knows their subject.
References
Cited by the original article, reproduced with its original numbering:
Bone & Mills (2013) Principles and Practice of Phytotherapy. 2nd ed. Elsevier UK.
Woelkart & Bauer (2007) The Role of Alkamides as an Active Principle of Echinacea. Planta Med 73(7):615-623.
Sun, Currier & Miller (1999) The American coneflower: a prophylactic role involving nonspecific immunity. J Altern Complement Med. 1999;5(5):437-46.
Raudner et al. (2006) Alkylamides from Echinacea are a new class of cannabinomimetics. Cannabinoid type 2 receptor-dependent and -independent immunomodulatory effects. J Biol Chem 281(20):14192-206.
Gertsch et al. (2004) Echinacea alkylamides modulate TNF-alpha gene expression via cannabinoid receptor CB2 and multiple signal transduction pathways. FEBS Lett. 577(3):563-9.
McIntosh A, D'Huyretter K, Goldberg B, et al. (1999) Infections prevention by herbal formulas in a high stress population. AANP Convention, Coeur d'Alene.
Tiralongo et al. (2012) Randomised, Double Blind, Placebo-Controlled Trial of Echinacea Supplementation in Air Travellers. Evid Based Complement Alternat Med. 2012;2012:417267.
Hubbert et al. (2006) Efficacy and tolerability of a spray with Salvia officinalis in the treatment of acute pharyngitis — a randomised, double-blind, placebo-controlled study with adaptive design and interim analysis. Eur J Med Res 11(1):20-6.
