I woke up yesterday morning with a brutal cold. Before I began to learn how to use reason and how to look for the evidence, I would just take health care advice based on popular belief. Something I hear all the time, and something that I used to repeat myself, is that you should take echinacea to fight a cold and to boost your immune system.
But if echinacea is so effective, why isn’t there any in my NyQuil?
According to the Wikipedia entry on echinacea, the idea that echinacea helps treat the common cold began when a Swiss herbal supplement maker was incorrectly told that Native American tribes in South Dakota used it for cold prevention.
But despite its questionable beginnings as a cold medicine, it has still become an extremely popular remedy, at least among my friends and family. So is there evidence behind echinacea to convince me that it is efficacious?
This University of Connecticut study claims that “Echinacea, the most popular herbal supplement in the United States, cuts the chances of catching the common cold by 58 percent and reduces the duration of the common cold by 1.4 days.” Sounds good to me! Unfortunately, this study has come under a lot of criticism.
The problem is that it’s a meta-analysis of smaller studies. Meta-analyses can be useful, however in this case critics say that the smaller studies are too dissimilar to be used accurately in a meta-analysis, so this study is not reliable enough to be taken as solid evidence for the efficacy of echinacea.
The gold standard of evidence in medicine is the large, placebo-controlled, double-blinded study. The closest to this type of study that has been done on echinacea is this one, done by the University of Virginia:
In one of the largest, multi-center clinical trials to study the effectiveness of the popular herbal cold supplement, Echinacea, researchers at the University of Virginia Health System have found that it has no effect on treating the common cold.
Turner and colleagues tested the efficacy of Echinacea on 399 volunteers between 2002 and 2004. The volunteers tested were recruited from UVa and were all susceptible to an experimental cold virus, rhinovirus type 39. They were divided into seven different groups and exposed to the cold virus through the nose.
Each group then received either a placebo or one of three possible Echinacea treatments (extracts of the herb originally used by Native Americans and endorsed by the World Health Organization for cold treatment). Volunteers were ‘blinded’ and did not know what treatment they were given. After five days of being studied in an isolated setting, there were no significant effects with Echinacea on the rates of infection or the severity of cold symptoms seen among the study participants. About ninety percent of all participants were infected with the cold virus.
“The results of this study demonstrate that, as tested, the putative active constituents of E. angustifolia do not have clinically significant effects on rhinovirus infection or illness,” Turner wrote in the study. Researchers from Karl-Franzens-Universitaet in Graz, Austria; the Medical University of South Carolina and Clemson University collaborated on the research.
So no good evidence yet that echinacea does anything for the common cold.
This large trial has also come under criticism, however this time from Dr. Michael Murray, a manufacturer of echinacea. He says that the study used the wrong type of echinacea and in the wrong dosages.
I wonder why Dr. Murray hasn’t funded a study himself to prove the effectiveness of the herb? If he’s so confident in its efficacy then he would be doing himself a favour by proving that it works. Echinacea would become a part of mainstream medicine if it were shown to be effective, it would be recommended by doctors, and Murray would be able to manufacture and sell more.
For now, the burden of providing evidence lies with its advocates. Until they provide reliable evidence that shows that echinacea is good for my health I’ll continue taking my NyQuil to alleviate my cold symptoms, which is proven by science and which outlines its possible side-effects on the box so I can be informed as to any risks it may carry (unlike my bottle of echinacea pills).