Commentary: Time to Research Echinacea Properly.

Abstract

1027 This issue carries a study “Echinacea purpurea for Prevention of Upper Respiratory Tract Infections in Children,” by Weber et al. (pp. 1021–1026). Despite the beneficial outcome from use of this herb reported by the authors, would-be users of echinacea (Echinacea spp.) can be forgiven for feeling fraught in trying to come to grips with a stream of recent contradictory press stories about the efficacy of this well-known medicinal herb. These users are caught in the increasingly partisan crossfire between researchers who, on the one hand, claim that taking echinacea to treat colds and flu is at best no better than placebo, and on the other hand, researchers who assert that the remedy can indeed reduce the symptoms of colds and flu. To confuse the picture still further, over-the-counter (OTC) echinacea products come in a bewildering range of forms (pills, freeze-dried powders, tinctures, fluid extracts, fresh juices, and teas) at different concentrations and recommended dosages. A Cochrane Systematic Review of echinacea1 notes that there are more than 200 different preparations of echinacea on the market. Moreover, such products contain any one or combination of at least three species of echinacea (E. angustifolia, purpurea, and pallida) and may contain extracts of echinacea root or leaf or both. How can one make any sense of all this? It seems that researchers, too, are just as bewildered as the general public since, while a particular herbal study may be well-designed and run, all too often, researchers who are designing a trial make the elementary mistake of failing to ensure the quality of the herb or even its species or dosage, thus making nonsense of their findings. Nor is this muddle confined just to echinacea. Writing in the American Journal of Medicine, researchers from Denver2 assessed the extent to which recently published randomized controlled trials of single herbal preparations of echinacea, garlic (Allium sativa), gingko (Gingko biloba), saw palmetto (Serenoa repens), or St John’s wort (Hypericum perforatum) had bothered to characterize and verify the content of the herbal products under study. In the 81 randomized controlled trials reviewed, only 15% reported undertaking tests to quantify the content of the herbal remedies being used while only 4% provided adequate data to compare actual with expected content values of at least one chemical constituent in the products. The authors of the American Journal of Medicine paper noted that, in the 3 studies of 81 that had compared actual with expected content values of one chemical constituent, the content varied widely between 80% and 113% of expected values.2 We need to take this lack of precision into account when evaluating research into echinacea published in even the most prestigious medical journals It is not just the quality or authentication of the plant under study that is critical to the success of any herbal research. The dosage of the remedy is also obviously a crucial matter. Most herbal practitioners I know, use relatively high doses of echinacea to treat a cold or flu at the onset of symptoms. Whenever I begin to get a cold, I immediately commence taking 5 mL of a 1:5 tincture (45% ethanol) of E. angustifolia root in water about every 3 hours, throughout the day, thus taking approximately 20–25 mL per day. This corresponds to a dose of approximately 4–5 g of the dried root per day day. It is noteworthy that the dosage recommended in a well-known textbook on herbal medicine for short-term use in acute conditions is well in excess of this—ranging from 10 to 15 g of the dried root of E. angustifolia per day (or its equivalent in liquid or tablet preparations).3 The British Herbal Compendium4 recommends as a standard dose up to 5 mL of a 1:5 tincture of dried root of E. angustifolia three times per day. This equates to 3 g of the dried root per day—which is the dosage of dried root also recommended by this publication. The Compendium comments that, in 1987, it became apparent that a considerable amount of E. angustifolia cultivated in Europe was in fact E. pallida and warns that data on E. angustifolia published prior to 1987 and based on material of commerce from European sources should thus be reviewed with caution.4 In the United States, doctors of the Eclectic tradition, such