As a follow up to my earlier post about alternative medicine and influenza, I did a little more probing among immunologist contacts of contacts.
There are several facts to consider if you’re thinking of taking echinacea to help protect you from swine flu, or indeed any form of influenza or colds.
Generally, taking these complementary therapies is probably a little like shutting the stable door after the proverbial horse has bolted, if you’re already got a cold/flu (of any strain). Taken as a preventative, however, there is some clinical evidence that echinicea can lessen the symptoms of the common cold (Shah et al, see footnote reference) but only if you’re been taking it for a while before (perhaps a week or a few weeks before you get the flu/cold virus. But, you have to give yourself a break from taking this herbal remedy every once in a while as its efficacy wears off if you take it all the time, there is scant evidence to explain why or to give a specific optimal stop and start time.
Many of the deaths of the 1918 flu pandemic were among healthy young men, due to the immune system going into overdrive – the so-called cytokine storm. In contrast, seasonal flu tends to kill the elderly, with secondary infections, such as bacterial pneumonia setting in. However, at the time of the 1918 pandemic medicine did not fully understand the nature of the infection let alone the cause of deaths. At the moment, it is not entirely clear what caused the recent deaths in Mexico ascribed to swine flu. So, it is difficult to unscramble cause and effect and whether H1N1 (swine flu is causing a cytokine storm or something else).
The scientific literature suggests that these herbal remedies aren’t powerful enough in their effects to make any difference to a full-blown cytokine storm. But, it’s worth considering how they might work if at all. Do they stimulate the immune system or reduce viral load? Echinacea supposedly stimulates the production of neutrophils and T cells, but also has antiviral properties.
Concerns about “adding to” the cytokine storm may be unfounded if one recent laboratory test (Sharma et al, 2009) proves true because that test suggest that echinacea may reverse cytokine production. However, a more recent study suggests it could enhance cytokine production (Senchina et al, 2009).
Sharma et al (2009). Induction of multiple pro-inflammatory cytokines by respiratory viruses and reversal by standardized Echnicea, a potent anti-viral herbal extract. Antiviral Res. 2009 in press.
Senchina et al (2009). Echinacea tennesseensis ethanol tinctures harbor cytokine- and proliferation-enhancing capacities. Cytokine2009 May;46(2):267-72.
A factor that confounds almost all studies of any herbal medicine, is that different parts of the plant, different members of the family, different extraction processes, quantification of active substances, and contra-indications for other drugs and conditions should all be considered in any assessment.
Echinacea is interesting but its efficacy is unproven. It might be worth trying for someone at risk, perhaps likely to come into contact with an infected individual but only if taken in advance and with advice from one’s physician.
Shah, S., Sander, S., White, C., Rinaldi, M., & Coleman, C. (2007). Evaluation of echinacea for the prevention and treatment of the common cold: a meta-analysis The Lancet Infectious Diseases, 7 (7), 473-480 DOI: 10.1016/S1473-3099(07)70160-3