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Cold Comfort for Echinacea Fans
By Michael Smith, MedPage Today Staff Writer
Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of Pennsylvania School of Medicine.
July 27, 2005
Also covered by: CBS News, MSNBC, USA Today
MedPage Today Action Points
Advise patients that the evidence for an effect of echinacea is mixed, with benefits appearing mostly in small, industry-sponsored trials which are often poorly designed.
Note that this study is large and well-designed; and its results are powerful evidence that there is no benefit from the three preparations that were tested.
Review
CHARLOTTESVILLE, Va., July 27-Echinacea deserves the cold shoulder, researchers here reported today. Despite popular lore, the alternative remedy neither prevents nor treats colds.
After a large randomized clinical trial that tested three different preparations of echinacea, the researchers reached a simple conclusion: It didn't work.
Echinacea didn't prevent a cold. Echinacea didn't ease symptoms.
Some other preparations of the Echinacea angustifolia plant might have an effect, conceded Robert Turner, M.D., of the University of Virginia School of Medicine, but it's not likely.
"Our study … adds to the accumulating evidence that suggests that the burden of proof (of efficacy) should lie with those who advocate this treatment." Dr. Turner and colleagues concluded in the July 28 issue of the New England Journal of Medicine.
They analyzed the results of a nasal challenge with rhinovirus 39 on 339 volunteers, in a seven-arm study that evaluated the three preparations either as prophylaxis and treatment or as treatment alone. A control group got placebo for both prevention and therapy.
Prophylaxis had no significant effect on rhinovirus infection and there was also no effect on the infection rate in the groups that received echinacea only in the treatment phase, the researchers found.
Indeed, 85% of the control group was infected and 66% came down with a clinical cold; the corresponding rates for the six active arms ranged from 81% to 92% and 50% to 75%.
Also, the amount of virus seen in the volunteers was not affected either by prophylaxis or treatment, the researchers added.
The echinacea also had no effect on symptom scores, proportion of subjects with clinical colds, nasal-secretion weights, or inflammatory markers, such as interleukin-8 and polymorphonuclear-leukocyte concentrations in nasal-lavage specimens.
Various constituents of echinacea -- alkamides, polysaccharides, and caffeic acid derivatives -- have been proposed as the active factors that have a beneficial effect; the preparations used in the study had different concentrations of these factors.
However, "none of the extracts had a detectable effect on rhinovirus infection or illness," Dr. Turner and colleagues concluded.
The findings should freeze out echinacea as a cold remedy, argues Dr. Wallace Sampson, M.D., of Stanford. Dr. Sampson, who is editor of Scientific Review of Alternative Medicine, wrote an accompanying editorial in the NEJM.
The trial was large, randomized, blinded, involved several institutions, and used standard nasal viral challenge methods, Dr. Sampson noted.
"So unless some obscure protocol violation occurred, the trial results are real," he concluded.
The study was supported by the National Center for Complementary and Alternative Medicine (NCCAM) of the National Institutes of Health; the center has three more clinical trials of echinacea under way, Dr. Sampson said.
Dr. Sampson argued that such studies are undertaken simply because of the popularity of the alternative remedy, not on the basis of plausible evidence of an effect.
"NCCAM, if it is to justify its existence, must consider halting its search for active remedies through clinical trials of treatments of low plausibility," he said.
The roots of Echinacea angustifolia -- also known as purple cone-flower -- were used by North American Indians to treat a variety of infections and wounds; commercial preparations became popular in the late 1800s to treat colds and regained popularity in North America in the 1960s.
Related article:
Cold Water Dashed on Vitamin C For Colds
Primary source: New England Journal of Medicine
Source reference:
Turner RB et al. An Evaluation of Echinacea angustifolia in Experimental Rhinovirus Infections. N Engl J Med 2005;353:341-8.
--------------------------------------------------------------------------------
Disclaimer
By Michael Smith, MedPage Today Staff Writer
Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of Pennsylvania School of Medicine.
July 27, 2005
Also covered by: CBS News, MSNBC, USA Today
MedPage Today Action Points
Advise patients that the evidence for an effect of echinacea is mixed, with benefits appearing mostly in small, industry-sponsored trials which are often poorly designed.
Note that this study is large and well-designed; and its results are powerful evidence that there is no benefit from the three preparations that were tested.
Review
CHARLOTTESVILLE, Va., July 27-Echinacea deserves the cold shoulder, researchers here reported today. Despite popular lore, the alternative remedy neither prevents nor treats colds.
After a large randomized clinical trial that tested three different preparations of echinacea, the researchers reached a simple conclusion: It didn't work.
Echinacea didn't prevent a cold. Echinacea didn't ease symptoms.
Some other preparations of the Echinacea angustifolia plant might have an effect, conceded Robert Turner, M.D., of the University of Virginia School of Medicine, but it's not likely.
"Our study … adds to the accumulating evidence that suggests that the burden of proof (of efficacy) should lie with those who advocate this treatment." Dr. Turner and colleagues concluded in the July 28 issue of the New England Journal of Medicine.
They analyzed the results of a nasal challenge with rhinovirus 39 on 339 volunteers, in a seven-arm study that evaluated the three preparations either as prophylaxis and treatment or as treatment alone. A control group got placebo for both prevention and therapy.
Prophylaxis had no significant effect on rhinovirus infection and there was also no effect on the infection rate in the groups that received echinacea only in the treatment phase, the researchers found.
Indeed, 85% of the control group was infected and 66% came down with a clinical cold; the corresponding rates for the six active arms ranged from 81% to 92% and 50% to 75%.
Also, the amount of virus seen in the volunteers was not affected either by prophylaxis or treatment, the researchers added.
The echinacea also had no effect on symptom scores, proportion of subjects with clinical colds, nasal-secretion weights, or inflammatory markers, such as interleukin-8 and polymorphonuclear-leukocyte concentrations in nasal-lavage specimens.
Various constituents of echinacea -- alkamides, polysaccharides, and caffeic acid derivatives -- have been proposed as the active factors that have a beneficial effect; the preparations used in the study had different concentrations of these factors.
However, "none of the extracts had a detectable effect on rhinovirus infection or illness," Dr. Turner and colleagues concluded.
The findings should freeze out echinacea as a cold remedy, argues Dr. Wallace Sampson, M.D., of Stanford. Dr. Sampson, who is editor of Scientific Review of Alternative Medicine, wrote an accompanying editorial in the NEJM.
The trial was large, randomized, blinded, involved several institutions, and used standard nasal viral challenge methods, Dr. Sampson noted.
"So unless some obscure protocol violation occurred, the trial results are real," he concluded.
The study was supported by the National Center for Complementary and Alternative Medicine (NCCAM) of the National Institutes of Health; the center has three more clinical trials of echinacea under way, Dr. Sampson said.
Dr. Sampson argued that such studies are undertaken simply because of the popularity of the alternative remedy, not on the basis of plausible evidence of an effect.
"NCCAM, if it is to justify its existence, must consider halting its search for active remedies through clinical trials of treatments of low plausibility," he said.
The roots of Echinacea angustifolia -- also known as purple cone-flower -- were used by North American Indians to treat a variety of infections and wounds; commercial preparations became popular in the late 1800s to treat colds and regained popularity in North America in the 1960s.
Related article:
Cold Water Dashed on Vitamin C For Colds
Primary source: New England Journal of Medicine
Source reference:
Turner RB et al. An Evaluation of Echinacea angustifolia in Experimental Rhinovirus Infections. N Engl J Med 2005;353:341-8.
--------------------------------------------------------------------------------
Disclaimer