Echinacea, placebo and upper respiratory tract symptoms
This is the latest study to compare the frequency of upper respiratory tract symptoms in people receiving E. purpurea capsules vs placebo.
First, the details.
- 90 hospital personnel were randomly assigned to take 3 capsules twice daily of placebo (parsley) or E. purpurea for 8 weeks during the winter months.
- Upper respiratory tract symptoms were reported weekly during this time.
- Neither the participants nor the researchers knew the treatment given (blinded).
And, the results.
- 58 individuals completed the study.
- Those in the echinacea group reported 9 sick days per person over 8 weeks.
- The placebo group reported 14 sick days.
- The differences were not significant.
- 8% of the echinacea group and 7% of the placebo group noted mild adverse effects.
The bottom line.
The authors concluded, “Prophylactic treatment with commercially available E. purpurea capsules did not significantly alter the frequency of upper respiratory tract symptoms compared with placebo.”
Taking echinacea after the onset of a cold shortens its duration or decreases the severity of symptoms according to the results of most clinical trials. But there’s no evidence that echinacea can prevent the onset of the common cold.
This study supports that position.
4/10/08 21:08