J Altern Complement Med 1995; 1 (2): 145–160
Melchart D, Linde K, Worku F, Sarkady L, Holzmann M, Jurcic K, Wagner H
Projekt Munchener Modell, Ludwig-Maximilians-Universitat Munchen, Germany
This article describes and discusses five placebo-controlled
randomized studies investigating the immunomodulatory activity of
preparations containing extracts of Echinacea in healthy
volunteers. A total of 134 (18 female and 116 male) healthy
volunteers between 18 and 40 years of age were studied. Two
studies tested intravenous homeopathic complex preparations
containing Echinacea angustifolia D1 (study 1) and D4 (study 5).
Two studies (2 and 3a) tested oral alcoholic extracts of roots of
E. purpurea, one study an extract of E. pallida roots (study 3b),
and one study an extract of E. purpurea herb (study 4). Test and
placebo preparations were applied for four (study 5) or five
(studies 1-4) consecutive days.
The primary outcome measure for immunomodulatory activity was the
relative phagocytic activity of polymorphonuclear neutrophil
granulocytes (PNG), measured in studies 1 and 2 with a
microscopic method and in studies 3, 4, and 5 with two different
cytometric methods. The secondary outcome measure was the number
of leukocytes in peripheral venous blood. Safety was assessed by
a screening program of blood and other objective parameters as
well as documentation of all subjective side effects.
In studies 1 and 2 the phagocytic activity of PNG was
significantly enhanced compared with placebo [maximal stimulation
22.7% (95% confidence interval 17.5-27.9%) and 54.0% (8.4-99.6%),
respectively], while in the other studies no significant effects
were observed. Analysis of intragroup differences revealed
significant changes in phagocytic activity during the observation
periods in five test and three control groups. Leukocyte number
was not influenced significantly in any study. Side effects due
to the test preparations could not be detected.
Our studies provide evidence for immunomodulatory activity of the
homeopathic combination tested in study 1 and the E. purpureae
radix extract tested in study 2. The negative results of the
other three studies are difficult to interpret due to the
different methods for measuring phagocytosis, the relevant
changes in phagocytic activity within most placebo and treatment
groups during the observation period, and the small sample sizes.
Future studies should be performed on patients rather than
healthy volunteers and use standardized or chemically defined
monopreparations of Echinacea.