Echinacea

Species-specific common names:
E. angustifolia: Narrow-leaf echinacea, Kansas
snakeroot, narrow-leaf purple coneflower
E. pallida: Pale-flower echinacea, pale purple coneflower
E. purpurea: Purple coneflower
Latin names:
Echinacea angustifolia DC. [Asteraceae]
Echinacea pallida (Nutt.) Nutt. [Asteraceae]
Echinacea purpurea (L.) Moench [Asteraceae]
Latin synonyms: E. purpurea = Rudbeckia purpurea L.
Plant parts: Aerial parts, root

Echinacea species are plants in the daisy family that have pale (occasionally
white) to deep purple flowers and are native to the central
plains of North America. Although nine species of echinacea have
been identified, only three are commonly used commercially. They
are Echinacea angustifolia, E. pallida, and E. purpurea. Historically,
there has been confusion over the identity of the plant material used
both commercially and in scientific studies. Echinacea angustifolia
root has been sold interchangeably with E. pallida roots. In addition,
E. purpurea has been adulterated or substituted with Parthenium
integrifolium L., a plant also known by the common name snakeroot.
Fortunately, modern techniques of botany and chemistry now allow
for better determination of identity (Awang and Kindack, 1991).
Many types of echinacea products are available on the market.
They differ in species, plant part, and method of preparation. The
most common products are the expressed juice of E. purpurea and
aqueous alcoholic extracts of the roots and/or tops of all three species.
Little scientific work has been done on possible differences in the action
 of these different preparations, although we know them to differ
chemically. Further, there is little scientific agreement as to which of
the numerous chemical constituents identified in echinacea are responsible
for the purported immunostimulatory action. Indeed, the
only consensus may be that numerous constituents have activity (Bauer
and Wagner, 1991).


Cold (Prevention and Treatment)

In the first well-conducted, placebo-controlled study, 118 employees
of a factory were enrolled at the initial signs of a cold. They were
treated for up to ten days with either EchinaGuard (20 drops every
two hours for the first day and subsequently three times daily) or placebo.
In the EchinaGuard group, only 40 percent experienced a “real”
cold with full symptoms, compared to 60 percent of the placebo
group. For those who developed a real cold, the time taken to improve
was four days compared to eight days for the placebo group (Hoheisel
et al., 1997).


Exercise-Induced Immunosuppression
A trial with EchinaGuard (Echinacin) studying the prevention of
exercise-induced immunosuppression included 40 triathletes who were
training for a competition. They were given 40 drops three times daily,
or a total of 8 ml per day. Small changes in immune parameters were
reported in comparison with the placebo group. None of the treatment
group developed colds, which were reported in a quarter of the control
groups (Berg et al., 1998). In the opinion of our reviewer, Dr. Richard
O’Connor, the trial would have benefited from a larger sample size and
more clearly described randomization process and outcome measures.

Vaginal Candidiasis

In a study examining the possible benefit of echinacea on recurrent
vaginal candidiasis, all patients were given econazole nitrate cream
topically, in addition to oral or injectable Echinacin or placebo. The
rate of reoccurrence was 60.5 percent for those treated only topically
with econazole and 16.7 percent following oral administration of
Echinacin, 30 drops three times daily. The reoccurrence rate was even
smaller when Echinacin was given subcutaneously (15 percent), intramuscularly
(5 percent), or intravenously (15 percent) (Coeugniet and
Kuhnast, 1986). However, according to Dr. O’Connor, the trial was so
badly designed and described that the benefit was deemed undetermined.