Echinacea And Colds
Chester J. Zelasko, Ph.D. |
August 26, 2005
work for colds.” That’s what the health and medical headlines read several
weeks ago. The battle is on between those who say echinacea is effective for
the reduction of the severity and duration of colds and those who say it
doesn’t work. First, let’s review the study and the results and then examine
the details of how the study was conducted.
The purpose of the study was to test the efficacy of a tincture of echinacea
on preventing colds and reducing the symptoms and duration of colds. The
researchers tested a large group of students to see if they were susceptible
to a specific strain of cold--rhinovirus 39. Those who were not susceptible
because they had been exposed to that strain of cold were excluded from the
study. The researchers prepared the echinacea tincture from the root of
Echinacea angustifolia (commonly known as narrow-leafed purple coneflower)
and administered it to half the subjects seven days before the exposure to
the cold virus and to all subjects for five days after exposure to the cold
virus. Subjects were sequestered in hotel rooms for the duration of the
study to prevent complicating exposures to other viruses.
There were no significant differences between those taking a placebo versus
those taking the tincture, or liquid echinacea solution, before and after
exposure to the cold virus. The same number of subjects got colds and had
the same number of symptoms and other measures of immune responses to colds.
Bottom line from the researchers: echinacea is ineffective.
There’s no question that this study was well designed. The researchers tried
to eliminate confounding factors; they gave the subjects the exact same type
of cold and the exact same tincture of echinacea. But in spite of their best
efforts, there were some major flaws in the study’s execution.
Only one type of echinacea: The researchers used
only a single form of echinacea and only a single part of the plant--the
root. Most herbal blends use multiple forms of echinacea; they use the root
and other parts of the plant as well.
Quantity of echinacea lower than recommended: The
subjects were given the equivalent of 900 mg of echinacea root in the
tincture over the course of the day; the researchers gave no explanation why
that amount was used. Typically, the amount of echinacea recommended at the
onset of a cold is two to six times the amount used in this study.
Subject loss higher than acceptable: Of all the
things not addressed by the researchers, this one is probably the most
disturbing from a statistical point of view. Eliminating subjects who have
been exposed to the specific form of the cold is understandable and
reasonable. But the researchers did not address why half the remaining
subjects chose not to participate in the study nor why another 10% dropped
out during the study. Subject loss that severe has dramatic effects on the
outcome of any study. The simplest explanation is that the subjects didn’t
want to get a cold or didn’t want to be sequestered in a hotel room for
days. But the researchers didn’t address this issue. We’ll never know.
Light-sensitive form of echinacea: Research has
demonstrated that echinacea in liquid form has some components that are
activated by exposure to light (3). While the researchers did a good job of
examining what phytonutrients were in the echinacea extract, if the
echinacea were left in glass jars exposed to the light for as little as five
minutes, the active ingredients could have been activated and rendered
ineffective by the time of administration.
The bottom line
The only reasonable conclusion is that this was a well-designed study that
was poorly executed. These are experienced researchers who approached this
as one would approach a pharmaceutical study. The problem is that they
didn’t appear to utilize anyone experienced in the typical use of this
herb--and that affected critical elements of the study.
In an editorial about the study in the same journal issue, Dr. Wallace
Sampson recommended that funding for alternative medicines be stopped
because they are not rooted in science and there is no evidence that they
work. In one aspect, Dr. Sampson may be correct: perhaps the U.S. government
should quit funding research on alternative medicine, but not because
alternative medicine is ineffective. If the National Center for
Complementary and Alternative Medicine is going to continue to fund studies
by scientists inexperienced in the basics of using herbal extracts, then the
money would best be spent on other research, because doing research this
poorly is a waste of taxpayer money.
Should you use echinacea or not? If you’ve found that it has been effective
for colds, flu, or other types of infections, there’s no reason to stop
based on this research. We at Better Life continue to use standardized
extracts of echinacea for one reason: in our experience, it works.
- Turner, RB, et al. An Evaluation of Echinacea angustifolia in
Experimental Rhinovirus Infections. N Engl J Med 2005;353:341-8.
- Sampson, W. Studying Herbal Remedies. N Engl J Med;
- Binns SE, et al. Light-mediated antifungal activity of Echinacea
extracts. Planta Med. 2000; 66(3):241-4.